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Cystic fibrosis and survival to 40 years: a case–control study

The clinical course of patients with cystic fibrosis (CF) is variable and probably determined by many interacting factors. We aimed to examine the influence of early social and clinical factors on long-term survival.

A case–control study of adult CF patients was used to compare long-term survivors (aged ≥40 yrs) with patients who died before reaching 30 yrs of age. Each case (n = 78) was matched by birth date with at least one control (n = 152), after exclusion of “late diagnosis” patients. Probability-weighted logistic regression models were used to identify influences on survival.

Factors resulting in increased probabilities of survival included high body mass index (OR 1.76, 95% CI 1.40–2.22), forced expiratory volume in 1 s (OR per 5% increase 1.54, 95% CI 1.32–1.80), and forced vital capacity (OR per 5% increase 1.54, 95% CI 1.33–1.78) at transfer to the adult clinic and the exclusive use of oral antibiotics (OR 8.31, 95% CI 3.02–22.88). Factors resulting in decreased probabilities of survival were Pseudomonas aeruginosa acquisition (OR 0.18, 95% 0.05–0.65) or pneumothorax before transfer to the adult clinic (OR 0.02, 95% CI 0.004–0.08) and referral from a paediatric clinic in a deprived area (OR 0.13, 95% CI 0.04–0.38).

Long-term survival is associated with the clinical features present by the time of referral to an adult clinic. Even “early-diagnosis” disease appears to have different phenotypes, possibly independent of CF gene function, that have different survival patterns.

The life expectancy of patients with cystic fibrosis (CF) has been steadily increasing despite the lack of a cure for the underlying cellular defect. Patients born today are expected to have a median survival into their 6th decade 1 . The improvement has been explained in several ways including through the introduction of pancreatic enzymes, better nutrition, specialist-centre care, improved physiotherapy and more intensive antimicrobial treatment 2 – 4 .

CF covers a wide spectrum of disease, from milder phenotypes with “non-classic” disease (with pancreatic sufficiency, milder lung disease and a later diagnosis), to more severe cases with a “classic” phenotype 5 . However, even within different groups there is variation in the rate of disease progression; some patients with features of classic disease run a mild course and indeed an important proportion of patients with the common “severe” δF508 mutation survive beyond 40 yrs of age with relatively well-maintained lung function and weight 6 , 7 .

Thus, it has been hypothesised that other factors influence survival in CF. These include variations in the function of the responsible gene, the cystic fibrosis transmembrane conductance regulator ( CFTR ), and other independent genetic factors (“modifier” genes). None, however, has yet been shown directly to influence survival 8 . Other potential, nongenetic determinants of survival are so-called environmental influences; these cover a diverse range of factors, broadly divided into biological effectors ( e.g. microorganisms, nutrition, sex and pollutants), social and cultural influences ( e.g. socioeconomic status and adherence to treatment) and healthcare-related factors, such as access to care and interclinic treatment variations 9 . Evidence for or against these factors is variable and when they are most influential, or when an individual is most vulnerable to them, is not well understood. In view of this, we conducted a case–control study of long-term survival among patients registered with a specialist adult CF clinic with the aim of identifying early potential influences of long-term survival in patients diagnosed with CF in childhood.

Since 1965, details of all patients referred to the adult unit at Royal Brompton Hospital (RBH; London, UK) and confirmed to have CF have been entered onto a database. The diagnosis is based on clinical features and a positive sweat sodium (>70 mmol·L −1 ) or chloride (>60 mmol·L −1 ) test or, in cases with a borderline or negative sweat test result, the presence of a known disease-causing mutation on each CFTR gene, or of an abnormal nasal potential difference measurement. Patients were referred as adults from an adult physician or by their general practitioner, or directly through transition from paediatric clinics (at ∼15 yrs of age). Clinical and demographic details are collected at the first consultation and are subsequently updated at annual review.

We studied only patients with a diagnosis of CF before the age of 17 yrs. These were identified from the database and classified as cases or controls as follows. Cases (long-term survivors) were all patients with complete records who had reached 40 yrs of age without transplantation by December 31, 2004. Controls were selected from all patients with complete records who had died before 30 yrs of age or required transplantation at <30 yrs of age by December 31, 2004. We excluded controls (n = 27) who had died from a non-CF related cause ( e.g. road traffic accident).

80 cases and 400 controls were identified from the original population. To ensure that cases and controls were similar in terms of era of birth, as it is likely that this would have influenced the nature of care received, cases were matched by date of birth (±365 days) to all eligible controls. Of the 80 cases identified, 78 were matched to at least one control. Each control was matched with as many cases as eligible and controls could be matched to more than one case. Of the 400 controls identified, 152 were matched to at least one case.

Information on source of referral, guardian's occupation, genotype and clinical state (weight, height, lung function, sputum microbiology, diabetic status, use of pancreatic enzymes, previous pneumothoraces, episodes of major haemoptysis and number of previous hospital admissions or antibiotic courses) prior to and at referral was collected from the initial assessment at the adult clinic; the remaining data were collected from annual reviews (school disruption, number of Advanced (“A”)-level school examinations and number of siblings). Antibiotic treatments before first attendance at the adult clinic were categorised as oral, aerosolised or i.v.

Statistical analysis

Differences between cases and controls were described by frequencies and proportions for categorical variables, and medians and interquartile ranges for continuous variables. Development of CF-related diabetes (CFRD) and the acquisition of Staphylococcus aureus , Pseudomonas aeruginosa and Haemophilus influenzae were assessed in terms of whether the patient developed these conditions before the age of 16 yrs. As such, analyses of these variables were limited to those who arrived at RBH by 16 yrs of age (69 cases and 109 controls). Physical measurements at initial assessment, history of antibiotic use and number of hospital admissions prior to initial assessment were limited to those arriving at RBH by the age of 15 yrs (73 cases and 131 controls).

We used probability-weighted logistic regression models to assess the association between possible predictors and survival to 40 yrs of age (case status). Using this method, controls were weighted according to the cases to which they were matched; thus, making the distribution of the matching variable (date of birth) similar in both groups. Each control was weighted by the sum, across its matched case, of 1/(number of controls to which the case is matched). Cases were allocated a weight of 1. Model results are presented as OR and 95% CI. Since patients were transferred to the adult clinic at varying ages, ORs for physical measures and medical history prior to initial assessment (use of antibiotics, prior hospital admissions, history of pneumothorax and major haemoptysis prior to initial assessment) were adjusted for age at assessment. ORs for physical measures were also adjusted for sex. Analyses were conducted in SAS v9.1 (SAS Institute, Cary, NC, USA) or STATA (StataCorp LP, College Station, TX, USA).

All patients consented for their anonymised data to be included in the database for research purposes. The study was approved by the RBH Research Ethics Committee.

Clinical characteristics

Half of the participants were born between 1960 and 1965 and most (80.4%) were diagnosed with CF before the age of 5 yrs ( table 1 ). 70% were first seen in the adult clinic before 21 yrs of age. 97% had pancreatic insufficiency and there were similar proportions of males in cases (long-term survivors) and controls. Genotyping was only possible for patients surviving beyond 1989 ( i.e. the year CFTR was discovered); therefore, genetic data were available for 74 patients (67 cases). Of the long-term survivors genotyped (86%), 32 (48%) were homozygous for δF508, 13 (19%) were compound heterozygous for δF508 and 19 (28%) were heterozygous for δF508 (with an unidentifiable second CF mutation). The remaining three cases were 621+1G→T, R553X (both with unidentifiable second genes) and R347P/3659delC. The seven controls genotyped were homozygous δF508.

Features significantly associated with case status ( i.e. long-term survivors) included diagnosis after 5 yrs of age. Patients whose initial presentation had been with respiratory disease were significantly less likely to be cases. Patients who had suffered a pneumothorax prior to referral to the adult clinic were significantly less likely to be cases after adjusting for age at first attendance. There was little heterogeneity in the distributions of pancreatic insufficiency, haemoptysis and CFRD prior to referral; none was associated with case status. After adjusting for age at initial assessment and sex, the probability of survival to 40 yrs increased with increasing height, weight, body mass index (BMI), forced expiratory volume in 1 s (FEV 1 ) and forced vital capacity as recorded at the initial assessment in the adult clinic.

Sociodemographic factors and patients’ educational background

Associations between long-term survival and measures of socio-economic status and educational attainment are shown in table 2 . Patients referred from paediatric clinic B (paediatric clinic in a low social economic status area) were less likely to be cases. Those whose guardians were in managerial or manual (skilled or unskilled) occupations were more likely to be cases than those in professional occupations, but the difference was not statistically significant. Patients classified as having “mildly” or “grossly” disrupted schooling were statistically more likely to be controls, but there was no association between case status and the number of A-levels achieved. We found no association between sibling number (with or without CF) and case status.

Sputum microbiology, antibiotic courses and hospital admissions

Table 3 displays the association between long-term survival and sputum microbiology, antibiotic courses and hospital admissions prior to referral to the adult clinic. Acquiring P. aeruginosa, but not H. influenza e or S. aureus, in the sputum prior to 16 yrs of age, was associated with a reduced probability of being a case.

Patients who had received oral antibiotics (as intermittent courses and/or long-term/prophylaxis), and had not received aerosolised or i.v. antibiotics, were significantly more likely to be cases than those who had not taken oral antibiotics. Conversely, the prior use of aerosolised or i.v. antibiotics was inversely associated with case status. Patients requiring annual or more frequent hospital admissions were significantly less likely to be cases.

This carefully matched case–control study is the first to report on the potential early influences of long-term survival in patients diagnosed with CF in childhood. Patients with a later diagnosis ( i.e. at 5–16 yrs of age), those whose CF did not present with respiratory disease and those with higher weight, height, BMI and lung function (% predicted) at the time of their first assessment at the adult clinic were statistically more likely to reach 40 yrs of age. Acquiring P. aeruginosa , but not H. influenza e or S. aureus , in the sputum prior to 16 yrs of age, was associated with a reduced probability of long-term survival. Factors that did not influence long-term survival included sex, parental occupation and major haemoptysis or the development of diabetes before 16 yrs of age. These findings suggest that the long-term survival of adults diagnosed with CF in childhood is determined predominantly by an intrinsically severe phenotype in early life, with little evidence of major modification by socioeconomic influences, and that maintaining good health in childhood is an important determinant of long-term survival.

We elected to study only patients whose disease had been diagnosed during childhood, and thus remove the bias associated with the good prognosis of disease when diagnosed in adulthood 10 , 11 . Moreover, by studying long-term survivors under the care of a single institution and by matching them with “controls” born within a year of their birth date, we reduced the effects of different adult treatment strategies between centres and changing strategies over time, each of which may have independent effects on survival 9 . We may, in this way, have “over-matched” patients, leaving insufficient heterogeneity of exposure to examine some important determinants of survival. For example, it is widely accepted that socioeconomic factors have a strong influence on prognosis 9 , 12 , 13 but our findings demonstrated only limited evidence of this. In contrast to a previous UK study in 1989, we found no correlation of parental occupation (an index of family socioeconomic status) with long-term survival 14 . The association of poor survival with referral from paediatric clinic B (situated in an area of relatively low socioeconomic status) may reflect differences in resources and provision of care, as well as patients’ sociodemographics.

However, the present study provides an important extra dimension to published studies on predictors of mortality. The earliest, observational, studies recognised the association of poor nutritional status and low FEV 1 with a worse outcome 15 – 17 . Since then, more robust epidemiological studies have confirmed this correlation, including a large population study of the Canadian Patient Data Registry 3 . More recently, an Irish study investigated factors relating to mortality in their adult patients, concluding that lower FEV 1 and BMI, and higher infection rates of P. aeruginosa and Burkholderia cepacia were associated with patients who had died 18 . They assessed differences in predetermined clinical parameters between patients who died during a 10-yr period and those who remained alive, therefore making it difficult to draw conclusions about the timing of the events ( i.e. when they were most influential). Our study adds to this by clearly showing the importance of these factors at an early stage.

The present study demonstrated a worse outcome in patients diagnosed with CF early (before 5 yrs of age) and also in those with an initial disease presentation of respiratory symptoms. This supports the findings of a US registry-based study, demonstrating variable survival among patients with inherently different degrees of baseline risk, reflected by their age at diagnosis and their degree of disease severity at presentation 19 . They also showed that meconium ileus was associated with reduced survival, which provides an explanation for the lack of correlation found in our study, as only a few patients presenting with meconium ileus survived to adulthood. Contrary to their findings, we found that sex did not predict survival, which, in part, might be explained by the historical higher mortality among CF females, particularly around puberty, taking its toll, thus leaving those who have a predetermined survival advantage to progress through to the adult clinic 20 . However, others have argued that the so-called “gender gap” does not exist, highlighting the complex interaction of this much-debated relationship 21 . Patients with an increased baseline risk are predisposed to developing worse lung disease and an accelerated decline in their general health. Consequently, they develop more complications and ultimately require more hospital admissions and i.v. antibiotic courses, as demonstrated by the strong correlation of these factors with control status in our study.

The negative impact on survival of P. aeruginosa infection is consistent with previous studies and, although there is still some controversy regarding causality and ascertainment bias, it should be regarded as a poor prognostic factor 22 , 23 . The insignificant impact of H. influenzae and S. aureus is consistent with other studies. A European cross-sectional study demonstrated that S. aureus was not associated with worse pulmonary status and others have shown a deleterious effect on symptoms only, including the risk of massive haemoptysis 24 – 26 . The finding of a survival benefit for patients receiving oral antibiotics (without aerosolised or i.v. antibiotics) is interesting, as oral flucloxicillin is usually given as long-term prophylactic anti-staphylococcal treatment, suggesting indirectly that S. aureus may be relevant to survival, although this association may also be an indicator of milder disease 27 .

We were unable to explore the impact on survival of specific CFTR mutations, as the majority of controls died before the discovery of the CF gene in 1989, making regression analysis impossible 28 . However, as 48% of the long-term survivors were homozygous for δF508 (compared with 50% in the total UK adult CF population 29 ), their survival advantage cannot be attributed to “milder” genotypes with less severe disease expression. We chose to use 17 yrs of age as our age criterion, as it has been demonstrated previously that this differentiates two distinct phenotypes of long-term survivors 11 . We acknowledge that we cannot be certain that all non-classic phenotypes have been excluded but combined with the genotype data and the fact that 97% of the total study population had pancreatic insufficiency, bias from genuine non-classic disease would have been minimal. Additionally, the use of a younger age of diagnosis would have further selected out “mild” cases; but with the recognition of significant disease heterogeneity even for homozygous δF508, reducing the age would have excluded patients with “classic” disease genotypes that follow a milder disease course ( e.g. due to gene modifiers), i.e. the group of patients of particular interest to this study.

There are several limitations to our findings. The incidence of complications such as CFRD and major haemoptysis increase with age 24 , thus numbers were small in both groups at the time of assessment in the adult clinic, limiting the likelihood of finding an effect on survival. We were unable to assess the impact of B. cepacia complex infection as the importance of this pathogen in CF became apparent only in the mid-1980s 30 . Asymptomatic patients, diagnosed at birth through neonatal screening, are also not included in this study, as such programmes have only recently been introduced. The study was further limited by the data available to us and, therefore, in some instances, proxy markers ( e.g. parental occupation) had to be used and patient numbers were small, making interpretation difficult. The information on socioeconomic status was therefore limited, as the broad category of “parental occupation” and the recognised limitations of “source of referral” do not allow for definitive conclusions to be made.

In summary, this study demonstrates the importance for long-term survival of achieving optimal growth and lung health by the time a patient attends an adult clinic. Effective clinical care is needed to facilitate this but, from our findings, we conclude that longevity is determined early, possibly by factors independent of CFTR function ( e.g. gene modifiers) that determine early phenotype, disease severity and, ultimately, the probability of long-term survival.

Statement of interest

None declared.

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Cystic Fibrosis

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Patient Terry Wright takes a Pulmonary Function Test

This crippling disease often goes under-diagnosed—unless you’re white

Anyone, of any ethnicity, can get cystic fibrosis. But for decades it has been overlooked in people of color, leading to misdiagnoses and dismal health disparities.

Terry Wright spent his childhood in Little Rock, Arkansas, struggling with severe stomach pain. “That initial blow when you first get kicked,” he says, “that was the pain, and it didn't go away.” 

He vomited after every meal, and the crippling stomachaches discouraged him from trying to eat or drink more, leading to severe malnutrition. Each trip to the emergency room yielded a different diagnosis—ulcers, a virus, the flu—and then doctors would inject him with painkillers. “That would just kind of hold me for a few hours. And then the pain would start back again,” he says. As he grew up, he had frequent sinus infections, and bronchitis and pneumonia, causing such severe sickness that he spent at least two-and-a-half weeks in the hospital every three months.

Wright, a fitness trainer, prize-winning master gardener, and naturalist, has struggled with these serious health issues his entire life. But he wasn’t diagnosed with cystic fibrosis—a rare, life-threatening genetic disease—until he was 54. He’d come close to being correctly diagnosed in 2000 when he was 38: A doctor told him, “If you were not Black, I would say you had cystic fibrosis.” 

Cystic fibrosis (CF) is one of the most common inherited diseases in white Americans—occurring in 1 in every 4,855 births—but mounting evidence suggests that the disease is more common in African Americans, South and East Asians, Hispanics, and Africans than previously recognized. A study published last year in Pediatric Pulmonology revealed that genetic screening of newborns was more likely to fail to detect cystic fibrosis in non-white babies than in white ones, suggesting the tests are poorly designed to identify the disease in people of color. For people with CF, late diagnosis is costly, boosting the risk for irreversible lung damage and other serious health outcomes.  

“We found there's huge disparities between babies of different races and ethnicities, and whether they're going to be detected,” says Meghan McGarry, a pediatric pulmonologist at the University of California, San Francisco, who led the study. “Diagnosis really depends on what your race and ethnicity is” she also says. “That's just unethical.” 

In addition, McGarry says, many medical professionals are still being incorrectly taught that CF is a white disease. 

What is disturbing to physicians who have heard Terry’s story is that he had the classic cystic fibrosis symptoms. “I feel like it's just another bit of evidence for systemic racism,” says Jennifer Taylor-Cousar, professor of internal medicine and pediatrics at National Jewish Health in Denver, Colorado. Taylor-Cousar thinks the physicians “didn't care” about Wright’s case. “It wasn't important to them. And so, they ignored it.”

When people are diagnosed late, “it impacts their health outcomes,” says Taylor-Cousar, who is Black. “It also makes them not trust the medical system, because they are repeatedly told the wrong information.” 

Most physicians and many pulmonologists had never examined a cystic fibrosis patient in 2000, the year Wright was misdiagnosed, let alone an adult patient, explains Larry Johnson, Wright’s pulmonologist and director of pulmonology and critical care medicine at the University of Arkansas for Medical Sciences. Johnson, who is also Black, is less inclined to attribute Wright’s dozens of misdiagnoses and treatments to racism. He says that in 2000, cystic fibrosis was considered a rare, pediatric disease because patients died so young, suggesting that may have been why Wright was overlooked. 

  Why is CF considered a 'white' disease?

Dorothy Andersen, a pathologist based at Babies Hospital in New York, first characterized cystic fibrosis, and published the seminal account in 1938 . From the beginning, she recognized the disease could affect anyone—not just white people. “One of the patients of the Babies Hospital was a Negro, and the parents of the others came from Puerto Rico, Italy, Germany, Ireland,” she wrote. 

But over the course of the next eight decades, the inherited condition became perceived as a white disease. Taylor-Cousar, who is the adult patient care representative on the Cystic Fibrosis Foundation’s Board of Trustees, suspects that was because the people who founded the foundation in 1955 were a small group of affluent white parents, the doctors were predominantly white, hospitals were still segregated in most places, and “so when the textbooks got written, they got written by the people with the money in the majority,” she says. “There wasn't enough of a voice of people of color to counteract that.” 

Because these texts were used in medical schools, it led to the perception that CF was a white disease, “and of course, that perpetuates itself,” leading to health inequities for people of color, says Taylor-Cousar. 

Today, the idea that CF is a white disease is a “misperception by those who have not been deeply involved in CF care,” says Mike Boyle, a pulmonologist who led the Johns Hopkins University Adult CF Program for 20 years and is the current CEO of the Cystic Fibrosis Foundation in Bethesda, Maryland. Physicians at Boyle’s CF center cared for many Black and Middle Eastern patients. But, he admits, that was unusual. Most health workers around the country have had limited exposure to CF patients, and those they meet are usually of Caucasian descent. This has led to missed and delayed diagnosis of CF, says Boyle, and contributed significantly to health outcome disparities for people of color.

Why are more white people affected by CF in the United States?

To develop cystic fibrosis, a child must inherit a genetic mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene from both parents. Since the gene was discovered in 1989 , more than 2,500 mutations have been identified, many of which can alter the structure of the CFTR protein and cause the disease. 

Anyone, of any ethnicity, can get this disease. But which mutations a person carries usually depends on ancestry. One in 25 white people in the U.S. whose ancestors came from western Europe carry a mutation in their CFTR gene called F508del—which is believed to have arisen about 5,000 years ago. It is the most common CF-causing mutation in the country. 

Currently there are believed to be about 40,000 people with CF in the U.S. —of these 91.4 percent are white, 3.5 percent African American, and 5.1 percent are of other races. But these stats are now being regularly revised as new mutations are identified in people of color. 

In other countries where people migrated from western Europe, the F508del mutation is also present, but less common. And mutations that have arisen spontaneously in Egypt, India, or China, for example, are completely different and are not included in routine genetic screening. Children with those genetic mutations are typically diagnosed late and can suffer permanent organ damage with dire consequences. 

When Andersen published her description of cystic fibrosis in the early 20th century, the disease could kill a baby before its first birthday—with malnutrition and/or lung infections often the main causes of death. But after she created a diagnostic test, the administration of digestive enzymes extended life expectancy to about 12 years old. In the 1990s, inhaled antibiotics and drugs that help clear deadly mucus from lungs pushed life expectancy into the early 30s. 

But in the past 10 years, breakthroughs in drug development have created revolutionary treatments. For those carrying certain mutations, the treatment is so effective that it is essentially a cure. And patients who receive these treatments in infancy are expected to live full lives, perhaps without any symptoms. Newborn screening and testing for all mutations, even the rare ones, is what allows these early life-changing interventions. 

Terry’s story

In 1999, Terry Wright met Michele Wise, who founded the National Society of Black Engineers at the University of Tennessee Space Institute but had pivoted to a career in pharmaceutical and biotechnology sales following a tenure as an electrical and industrial engineer. At the time, Terry’s inability to digest food became life threatening. Surgeons performed an operation on his damaged pancreas, rerouting digestive juices so they could reach his gut and enable him to absorb nutrients. But his lung infections got worse. During each hospital stay, doctors treated him with heavy doses of antibiotics and oxygen. 

When they married in November 2000, Michele knew she was stepping into the role of wife, caretaker, and advocate. She sensed from Terry’s medical history, and from the frequent visits they made to the emergency room every week, that the doctors were missing critical clues. “It was nothing but pain, suffering, and devastation” for the next 16 years, Michele says. 

In 2016, antibiotics failed to vanquish an infection in Terry’s lungs—and he spent Christmas and New Year’s in the hospital. Frustrated and desperate for another perspective, Michele took Terry to the University of Arkansas for Medical Sciences where she sought out an infectious disease specialist. After examining Terry, Keyur Vyas said that his symptoms seemed consistent with those of cystic fibrosis. He ordered the gold-standard diagnostic for the disease: a test that measures the salt concentration in sweat, which is particularly high in people with CF because the CFTR protein in the sweat glands malfunctions and releases too much salt. 

Terry tested positive for CF. Twice. 

CF newborn screening and health disparities

Since 2010, all 50 states have implemented a two-part newborn screening test for CF. The first part tests for high levels of a chemical called immunoreactive trypsinogen—which is a chemical made by the pancreas. If levels are too high, the baby’s DNA is screened for mutations that could cause cystic fibrosis. When a mutation is identified, early interventions that improve nutrition and lung health can save lives. 

But as Meghan McGarry’s study showed, the types of genetic mutations used to diagnose CF vary from state to state and have dramatically different impacts on detection of CF in various ethnic groups.

In Mississippi , the tests only screen newborn DNA for the most common CF-causing mutation in the Caucasian population: F508del. As a result, the state detected only 53.7 percent of African American babies that had the disease; 64 percent of Native Americans and Alaskans; 42 percent of Asians; and 66 percent of Hispanic patients. It identified 87.5 percent of white babies with CF. 

Even states that used more comprehensive genetic tests, which screened for 139 mutations, were not infallible. They detected only 83.4 percent of African Americans babies with CF; 91 percent of Native Americans and Alaskans; 90 percent of Hispanics; and 72.4 percent of Asians. But the tests found 96.7 percent of CF cases in white people. 

“But they didn’t look at all the mutations,” says Taylor-Cousar, “because we weren't acknowledging that disease existed in other people.”

Diagnosed through IVF

That was the case when a pulmonologist in Portland wrote in Sowmya Bobba’s medical chart that he suspected she had cystic fibrosis but wasn’t going to test her for it “because she was of an Asian race.” Bobba, who moved from Vijayvada, India, in 2013, had always suffered from coughs and colds but had never been treated with anything other than antibiotics, inhalers, and some steroids.

In 2018, after Bobba and her husband had been trying to conceive for a couple of years, she had a genetic test done as a standard part of an in vitro fertilization procedure. The tests revealed her ovaries were healthy and her husband’s sperm count was good. But the doctor who authorized the tests called her and asked, “Did you know you have cystic fibrosis?” 

“I had a lot of mixed reactions,” Bobba says. “I was very happy that I was diagnosed and knew that, OK, something was wrong with me.” But it also made her feel vulnerable and scared, paranoid of getting sick and fearful of dying young.  

In 2020, Bobba set up an appointment with Aaron Trimble, who directs the adult cystic fibrosis center at Oregon Health & Science University. There, a team of experts schooled her in nutrition, the hours-long nebulizer treatments, physical therapy she would need to do daily at home to keep her lungs healthy, and all the other aspects of living with the disease.

“The adults who lived like Sowmya for 30 years with symptoms…are the ones who tend to get overlooked,” Trimble says. “They were just sick enough to go to a doctor, get some antibiotics, get an inhaler, get something, get sort of better, and just get passed along.”

The drug Trikafta had been approved in 2019 for patients who carried the F508del mutation—the one that is most common in the U.S., not the one Bobba has. But the drug maker Vertex Pharmaceuticals kept testing the drug on cells with less common mutations, one by one, to see whether it would work for those. 

In 2021, Trimble delivered good news. The U.S. Food and Drug Administration said the drug could also treat Bobba’s rare mutation . He encouraged her to delay IVF treatments because he knew that women with CF-related infertility had conceived naturally after taking the drug. 

Bobba began taking Trikafta—just a single pill every day—beginning in November 2021. By early February 2022, she was pregnant. In October 2022, she gave birth to a healthy girl and is feeling great. With Trikafta she is freed from the hours spent doing breathing treatments.

These days when Trimble is working with medical students or with residents in the intensive care unit, he’ll ask them to share what they know about CF. Most know that cystic fibrosis causes chronic lung disease and limits lifespan. They know that the F508del mutation is the most common. “Most will say it is more common in people who are white or of European descent,” says Trimble. 

When he asks how common that mutation is in white people, only a few are aware that one in every 25 Caucasians carry it. But when Trimble asks about non-whites, “Nobody has any idea.”

CF in other countries

This disease affects people from every ethnic background, says Samya Nasr, a pediatrician and director of the Cystic Fibrosis Center at the University of Michigan. The incidence might be lower in other countries and among people of non-European ancestry, but statistics on its frequency are spotty or nonexistent because the mutations have not been identified and genetic testing isn’t common. “In the U.S., we see it in African Americans, we see it in Hispanics, we see it in Chinese Americans, Japanese Americans … Asian Indians. So it’s everywhere.” And that includes Egypt. 

When Nasr attended Ain Shams College of Medicine in Egypt, she was taught that CF didn’t occur in the country. “But that was false. Because really, if you don’t test for something, you’re not going to find it.”

In the early 2000s, Nasr began collaborating with faculty at Cairo University’s pulmonary and gastrointestinal clinic. They began testing the saltiness of patients’ sweat with equipment donated by a company in the U.S., and they found that 12 of the 60 patients they tested carried the disease. 

When the results were published, Cairo University invested in their own testing equipment and began diagnosing patients. So far, between 800 and 1,000 people have been diagnosed with cystic fibrosis, Nasr says. Since Nasr was able to arrange donations of sweat testing equipment to several universities in Egypt in 2021, the number of new patients has escalated. 

But without access to digestive enzymes to help children with nutrition and treatments to clear their lungs, survival for CF patients is about eight years in Egypt; in the U.S., it’s now 53. 

Nasr has teamed up with the Michigan-based Bonnell Foundation to get medicines and chest-clearing equipment donated to Egyptian patients, and to spread the word that people of color can get CF .

Going forward

After he was diagnosed in 2017, Terry Wright, with his wife Michele, founded the National Organization of African Americans with Cystic Fibrosis ( NOAACF ) to raise awareness of the disease among African Americans. 

In 2021, Trikafta was shown to be effective for Terry’s mutation, and he began taking it immediately. Even though his health was improving, he was keen to make sure that others didn’t repeat his medical odyssey. Working with Taylor-Cousar, the Wrights created a free screening tool to help Black, Indigenous, and other people of color, or their medical providers, determine whether they have symptoms that match CF. 

Boyle, the Cystic Fibrosis Foundation’s CEO, says the group is working with state health officials to explain the importance of expanding newborn screening to include a broader range of mutations that cause CF. The foundation is also addressing health inequities by independently testing cells carrying rare CF-causing mutations to find ones that may respond to Trikafta so more people of color may benefit.

Lathronia Jefferson, whose 12-year-old son Khaleb has CF, has had her share of run-ins at the ER when doctors have asked her whether she is sure that her son has CF. But her frustrating experiences have motivated her to work with the Cystic Fibrosis Foundation to educate medical providers. 

“If I'm having this much trouble, and my child is only 50 percent African American, what about someone who is 100 percent and has this disease? How are they dealing?” Now when someone says to her that CF is rare in African Americans or people of color she says: “It's just underdiagnosed in people of color. The light has just not been shone on the fact this is not just an Anglo-Saxon disease. People of color have this.”

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Cystic Fibrosis: Case Study

Cystic fibrosis (CF) is a disease caused by defective chloride transportation. The defect in chloride transportation is a result of metamorphosis within the cystic fibrosis gene leading to abnormalities of cyclic adenosine monophosphate (cAMP). Six categories of defects due to gene mutations include: total lack of gene synthesis; defective gene maturation and premature degradation; disorganized regulation; poor chloride conductance; weakened transcription owing to promoter abnormality; or hastened channel regeneration from the cell exterior (Ramsey, Davies, & McElvaney, 2011).

The gene mutations have low penetrance, which prevents the genotype from predicting the severity or occurrence of the disease. Defects in cystic fibrosis genetic composition lower chloride discharge and increase mucus dehydration. The lower mucus hydration makes it easier for bacteria to adhere to it, which increases inflammation and infection (Filburn, Lumeng, & Nasr, 2014).

The autosomal recessive inheritance of the cystic fibrosis gene means that most patients are heterozygotes or carriers as they have one homozygote and one heterozygote allele. Two heterozygous parents may therefore produce a child with the disease (Brooks, 2014, para. 12).

The following Punnett squares describe the Mendelian autosomal recessive inheritance of CF:

As earlier stated, the inheritance of cystic fibrosis is from two carriers. In Punnett diagram I, both parents are carriers of the recessive allele (c), therefore there is a one in four (25%) chance of an offspring with both c alleles resulting in cystic fibrosis. In Punnett diagrams II and III, there is no chance of inheritance since the recessive allele (c) is seen in only one parent.

The production of mucus from the airways is reinforced by Goblet cells and cilia. Goblet cells are specialized cells in the respiratory tract that secrete mucin (the sol or fluid component of mucus). In cystic fibrosis, mucin secretion is diminished leading to thickened mucus. Movement of cilia in the airway aids the clearance of viscous mucus (Ramsey et al., 2011). Mucus, high in viscosity, results in obstruction and impairs the ciliary function.

The functional defects of the goblet cells and cilia contribute to the pathogenesis of cystic fibrosis (Filburn et al., 2011). Pseudostratified epithelium, composed of goblet, ciliated, intermediate, and basal cells are seen in the normal respiratory tract. However, hyperplastic and metaplastic cellular changes (especially in the goblet/mucous-secreting cells) are observed in the respiratory linings of cystic fibrosis patients.

The typical symptoms of upper respiratory infection – fever, cough, fatigue, and runny nose – and those of gastrointestinal disease – anorexia and weight loss – are seen. Chronic diarrhea with pale fatty stool is also seen. Infants with cystic fibrosis may present with chronic and recurrent cough that may be productive of mucoid and later purulent sputum. Recurrent wheezing, pneumonia, atypical asthma, pneumothorax, chest pain, hemoptysis, and digital clubbing are all respiratory complications of cystic fibrosis (Brooks, 2014, para. 18).

Meconium ileus, steatorrhea, failure to thrive, bilious vomiting, intussusception, or rectal prolapse and features of insufficiency of the exocrine pancreas such as malabsorption, flatulence or foul-smelling flatus, recurrent abdominal pain and distension are also seen in the gastrointestinal system. Children of cystic fibrosis may present with undescended testes, hydrocele and delayed puberty. Clinical signs of the index case include fever (101.7 0 F), tachycardia (HR = 122bpm), tachypnea (RR – 32cpm) and use of accessory muscles.

The gold standard for testing cystic fibrosis is the sweat test. This test involves the quantitative measurement of the amount of chloride in sweat. The upper limit value of chloride used is 29 mmol/L. A value of chloride in sweat 30mmol/L and above is significant and values >= 60mmol/L are diagnostic of cystic fibrosis. Sweat-chloride concentration of 30 – 59 mmol/L is considered intermediate (Brooks, 2014, para. 4).

In cystic fibrosis, defective chloride transportation across epithelial cells of sweat glands results in the excess amount of chloride measured in the sweat. The mutation of the CFTR protein, which is present in cystic fibrosis results in a defect in chloride transport across the epithelial cells of sweat glands and consequently in increased sodium and water reabsorption (LeGrys, Yankaskas, Quittell, Marshall, & Mogayzel, 2007). This is responsible for the significantly high amount of chloride measured in the sweat.

The pancreatic enzymes involved in cystic fibrosis are pancreatic lipase, pancreatic amylase, and protease. Pancreatic lipase aids in the breakdown of fats, pancreatic amylase aids in the breakdown of carbohydrate, and protease aids in the breakdown of protein.

Poor airway clearance as a result of obstruction from excessive mucus.

Malnutrition due to loss of appetite and calorie losses.

Anxiety as a result of breathlessness.

Brooks M. (2014) FDA OKs Expanded Use of Ivacaftor (Kalydeco) in Cystic Fibrosis: Medscape Medical News . Web.

Filburn A., Lumeng C. & Nasr S. (2011). Infant pulmonary function testing guides therapy in cystic fibrosis lung disease. Respiratory Medicine CME. 4 (1), 17-19.

LeGrys V., Yankaskas J., Quittell L., Marshall B. & Mogayzel, P. (2007). Diagnostic sweat testing: the Cystic Fibrosis Foundation guidelines. Journal of Pediatrics, 151 (1), 85-89.

Ramsey, B., Davies J. & McElvaney N., (2011). A CFTR potentiator in patients with cystic fibrosis and the G551D mutation. New English Journal of Medicine, 365 (18), 1663-72.

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Case Study - What is the Relationship Between the Cell Membrane and Cystic Fibrosis?

baby

Dr. Weyland examined a six month old infant that had been admitted to University Hospital earlier in the day. The baby's parents had brought young Zoey to  the emergency room because she had been suffering from a chronic cough. In addition, they said that Zoey sometimes would "wheeze" a lot more than they thought was normal for a  child with a cold.   Upon arriving at the emergency room, the attending pediatrician noted that salt crystals were present on Zoey's skin and called Dr. Weyland, a pediatric pulmonologist.    Dr. Weyland suspects  that baby Zoey may be suffering from cystic fibrosis.

CF affects more than 30,000 kids and young adults in the United States. It disrupts the normal function of epithelial cells — cells that make up the sweat glands in the skin and that also line passageways inside the lungs,  pancreas, and digestive and reproductive systems.

The inherited CF gene directs the body's epithelial cells to produce a defective form of a protein called CFTR (or cystic fibrosis transmembrane conductance regulator) found in cells that line the lungs, digestive tract, sweat glands, and genitourinary system.

When the CFTR protein is defective, epithelial cells can't regulate the way that chloride ions pass across cell membranes. This disrupts the balance of salt and water needed to maintain a normal thin coating of  mucus inside the lungs and other passageways. The mucus becomes thick, sticky, and hard to move, and can result in infections from bacterial colonization.  

case study about cystic fibrosis

1.   "Woe to that child which when kissed on the forehead tastes salty. He is bewitched and soon will die"

This is an old saying from the eighteenth century and describes one of the symptoms of CF (salty skin).  Why do you think babies in the modern age have a better chance of survival than babies in the 18th century?

2.  What symptoms lead Dr. Weyland to his initial diagnosis?

3.  Consider the graph of infections,  which organism stays relatively constant in numbers over a lifetime?

    What organism is most likely affecting baby Zoey?

4. Explain how the CF gene affects the cell membrane.

5. Consider what you know about TONICITY and the cell membrane. Why is it important to regulate salt in cells?

Part II:  CF is a disorder of the cell membrane.

Imagine a door with key and combination locks on both sides, back and front. Now imagine trying to unlock that door blind-folded. This is the challenge faced by David Gadsby, Ph.D.,  who for years struggled to understand the highly intricate and unusual cystic fibrosis chloride channel – a cellular doorway for salt ions that is defective in people with cystic fibrosis.

His findings, reported in a series of three recent papers in the Journal of General Physiology, detail the type and order of molecular events required to open and close the gates of the cystic fibrosis chloride channel, or as scientists call it, the cystic fibrosis transmembrane conductance regulator (CFTR).

Ultimately, the research may have medical applications, though ironically not likely for most cystic fibrosis patients. Because two-thirds of cystic fibrosis patients fail to produce the cystic fibrosis channel altogether, a cure for most is expected to result from research focused on replacing the lost channel.

case study about cystic fibrosis

6.  Compare the normal and the mutant CFTR protein.  How would you correct the mutant protein if you had the ability to tinker with it on a molecular level?

7.   Why would treatment that targets the CFTR channel not be effective for ⅔  of those with cystic fibrosis? 8.  Sweat glands cool the body by releasing perspiration (sweat) from the lower layers of the skin onto the surface. Sodium and chloride (salt) help carry water to the skin's surface and are then reabsorbed into the body.  Why does a person with cystic fibrosis have salty tasting skin?

Part III: No cell is an island

Like people, cells need to communicate and interact with their environment to survive. One way they go about this is through pores in their outer membranes, called ion channels, which provide charged ions, such as chloride or potassium, with their own personalized cellular doorways. But, ion channels are not like open doors; instead, they are more like gateways with high-security locks that are opened and closed to carefully control the passage of their respective ions.

case study about cystic fibrosis

9. Which mutation do you think would be easiest to correct? Justify your answer.

10. Consider what you know about proteins, why does the "folding" of the protein matter?

Part IV: Open Sesame

channel protein

Among the numerous ion channels in cell membranes, there are two principal types: voltage-gated and ligand-gated. Voltage-gated channels are triggered to open and shut their doors by changes in the electric potential difference across the membrane. Ligand-gated channels, in contrast, require a special “key” to unlock their doors, which usually comes in the form of a small molecule.

CFTR is a ligand-gated channel, but it’s an unusual one. Its “key” is ATP, a small molecule that plays a critical role in the storage and release of energy within cells in the body. In addition to binding the ATP, the CFTR channel must snip a phosphate group – one of three “P’s” – off the ATP molecule to function. But when, where and how often this crucial event takes place has remained obscure.

11. Label the image to the right to show how the ligand-gated channel for CFTR works. (Structures: Ligand-gated channel protein, ATP, phospholipids). Summarize how this channels works.

12. Where is ATP generated in the cell? How might ATP production affect the symptoms of cystic fibrosis?

Part V: Can a Drug Treat Zoey's Condition?

Dr.  Weyland confirmed that Zoey does have cystic fibrosis and called the parents in to talk about potential treatments.    “Good news, there are two experimental drugs that have shown promise in CF patients.  These drugs can help Zoey clear the mucus from her lungs.   Unfortunately, the drugs do not work in all cases.”    The doctor gave the parents literature about the drugs and asked them to consider signing Zoey up for trials.

The Experimental Drugs

Ivacaftor ™  is a potentiator that increases CFTR channel opening time.  We know from the cell culture studies that this increases chloride transport by as much as 50% from baseline and restores it closer to what we would expect to observe in wild type CFTR. Basically, the drug increases CFTR activity by unlocking the gate that allows for the normal flow of salt and fluids.

In early trials,  144 patients all of whom were over the age of 12 were treated with 150 mg of Ivacaftor twice daily. The total length of treatment was 48 weeks. Graph A shows changes in FEV  (forced expiratory volume) with individuals using the drug versus a placebo. Graph B shows concentrations of chloride in patient’s sweat.

case study about cystic fibrosis

13. What is FEV (if you're not sure, look this one up)? Describe a way that a doctor could take a measurement of FEV.

14. Why do you think it was important to have placebos in both of these studies?

15. Which graph do you think provides the most compelling evidence for the effectiveness of Ivacaftor. Defend your choice.

16. Take a look at the mutations that can occur in the cell membrane protein from Part III. For which mutation do you think Ivacaftor will be most effective. Justify your answer.

17. Would you sign Zoey up for clinical trials based on the evidence? What concerns would a parent have before considering an experimental drug?

Part VI: Zoey's Mutation

Dr. Weyland calls a week later to inform the parents that genetic tests show that Zoey chromosomes show that she has two copies of the F508del mutation.   This mutation, while the most common type of CF mutation, is also one that is difficult to treat with just Ivacaftor.  There are still some options for treatment.   

In people with the most common CF mutation, F508del, a series of problems prevents the CFTR protein from taking its correct shape and reaching its proper place on the cell surface.   The cell recognizes the protein as not normal and targets it for degradation before it makes it to the cell surface. In order to treat this problem, we need to do two things: first, an agent to get the protein to the surface, and then ivacaftor (VX-770)  to open up the channel and increase chloride transport. VX-809 has been identified as  a way to help with the trafficking of the protein to the cell surface.  When added VX-809 is added to ivacaftor  (now called Lumacaftor,)  the protein gets to the surface and also increases in chloride transport by increasing channel opening time.

In early trials,  experiments were done in-vitro, where studies were done on cell cultures to see if the drugs would affect the proteins made by the cell.   General observations can be made from the cells, but drugs may not work on an individual’s phenotype.   A new type of research uses ex-vivo experiments, where rectal organoids (mini-guts) were grown from rectal biopsies of the patient that would be treated with the drug.    Ex-vivo experiments are personalized medicine, each person may have different correctors and potentiators evaluated using their own rectal organoids.  

The graph below shows how each drug works for 8 different patients (#1-#8). Swelling in the organoid indicates the the channels within the cell membrane are allowing material to pass.

case study about cystic fibrosis

19. . Compare ex-vivo trials to in-vitro trials.   

20.   One the graph, label the group that represents Ivacaftor and Lumacaftor. What is the difference between these two drugs?

21.  Complete a CER Chart.  

If the profile labeled #7 is Zoey, rank the possible drug treatments   in order of their effectiveness for her mutation.  This is your CLAIM.

Provide EVIDENCE to support your claim  

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Source & Credits

Follow-up Article: What it's like to have two kids with cystic fibrosis More information at John Hopkins Cystic Fibrosis Center

Creative Commons License

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Cystic Fibrosis Case Study

The role genetics plays in the disease.

Cystic Fibrosis (CF) is a disease that is inherited and affects the mucus and sweat production by those glands (McCance & Huether, 2018).  How it is inherited is that parents of children with CF both have to be carriers of the cystic fibrosis transmembrane regulator (CFTR) mutation gene (McCance & Huether, 2018).  Parents do not have to have CF for their children to have CF; they just have to be carriers of the mutation gene (Tabori et al., 2017).  It is very common for people of European descent to inherit CF (McCance & Huether, 2018).

Why the patient is presenting with the specific symptoms described.

The symptoms described in the case study scenario that contributed to the CF diagnosis were thought of possible colic, baby has had many episodes of crying after eating, despite having a good appetite baby is not gaining weight (failure to thrive, FTT), baby’s belly “gets all swollen sometimes,” the baby tastes “salty” when the mother kisses the baby, and sibling has had multiple episodes of “chest congestion” and was hospitalized once for pneumonia (Abid et al., 2017).

The human body is protected against bacteria by first and second lines of defense (McCance & Huether, 2018).  Physical, mechanical, biochemical, and normal flora make up the first lines of defense (McCance & Huether, 2018).  Examples of the physical and mechanical barriers are skin and mucus membranes; antibacterial properties of mucus secretions, tears, saliva, sweat, and other secretions are examples of biochemical barriers; normal flora are good bacteria that protects the human body by preventing bad bacteria from taking over in places like the gut (McCance & Huether, 2018).

CFTR protein pushes chloride ions into secretions to help draw water into these secretions (mucus) to loosen (thin) them (McCance & Huether, 2018).  CFTR protein absence leaves excess chloride ions on the skin.  The thin and slippery mucus protects the sac that lines the lungs, stomach, tissues and organs (McCance & Huether, 2018).  The missing CFTR protein does not leave a way for the body to thin out the mucus (Abid et al., 2017), leaving the body to only make thick and sticky mucus that build up, leading to blockages, frequent infections, and damages in the affected organs (McCance & Huether, 2018).

The pancreas cannot release any digestive enzymes to the small intestine when it is blocked with thick mucus making nutrients and fat not absorbable, leading to FTT (not gaining weight despite good appetite and looking malnourished (McCance & Huether, 2018).  Other gastrointestinal symptoms include fatty stools (McCance & Huether, 2018), abdominal pain after eating due to poor intestinal malabsorption (Tabori et al., 2017), abdominal bloating, constipation, and flatulence (McCance & Huether, 2018).  CFTR also helps the skin regulate sodium ions and fluid absorption; so, in someone with CF, there is less fluid absorption to dilute the sodium ions, leaving the salty taste on the skin (McCance & Huether, 2018).

The second line of defense is the body’s response to damage known as inflammation (McCance & Huether, 2018).  Symptoms are redness, swelling, pain, and heat, collection of fluid at the site, leukocytosis and fever (McCance & Huether, 2018).  In the presence of CF, inflammation causes damage to lungs and pancreas in particular, but other organs as well (McCance & Huether, 2018).  A child or young adult, or their sibling, with a history of severe and recurrent bronchitis, pneumonia, pancreatitis, and hemoptysis is suspect for further CF testing.

The physiologic response to the stimulus presented in the scenario and why you think this response occurred .

In CF, abnormally thick mucus in the airways does not have the same germ-killing properties of normal mucus leading to frequent infections that hampers attempts at treating (clearing) the infections, resulting in a loop of continuous inflammations, scarring, and death (McCance & Huether, 2018).  Viral and bacterial infections, especially culprits like Pseudomonas aeruginosa, Staphylococcus aureus, and Hemophilus influenzae, manifest inflammatory responses that are extreme (McCance & Huether, 2018).  Excessive signals are sent from cells with a defective CFTR protein, resulting in the complement system of antigen-antibody being activated (McCance & Huether, 2018); bacteria, leukocytes (white blood cells) and phagocytes (neutrophils).

The cells that are involved in this process.

The mast cell activates the inflammatory response through the release of mediators such as histamine (McCance & Huether, 2018).  Antigens of the bacteria are presented to helper T cells, who release cytokines, resulting in accumulation of neutrophils (to initiate phagocytosis of the bacteria), signaling or resulting in inflammation (McCance & Huether, 2018).

How another characteristic (e.g., gender, genetics) would change your response.

While some people with CF get severe symptoms or life-threatening complications, others have few signs and symptoms (Tabori et al., 2017), such as with the baby and older sibling in the case study scenario.  Siblings with only one parent in common who is a carrier will not acquire CF.  Abid et al. (2017) reported estrogen hormone elevations disrupt chloride ion and water balance (p. 2). They also measured nasal epithelial Calcium ion-activated Chloride-secretion in women with CF during their menstrual cycle with results that women with CF cannot clear build-up of airway secretions, a hallmark of CF, effectively (Abid et al., 2017).

Abid, S., Xie, S., Bose, M., Shaul, P., Terada, L., Brody, S.,…Jain, R. (2017). 17β-Estradiol Dysregulates Innate Immune Responses to Pseudomonas aeruginosa Respiratory Infection and Is Modulated by Estrogen Receptor Antagonism. Infection and immunity , 85 (10), e00422-17. Https://doi.org/10.1128/IAI.00422-17 .

McCance, K. & Huether, S. (2018). Pathophysiology: The biologic basis for disease in adults and children (8th ed.). St. Louis, MO: Mosby/Elsevier.

Tabori, H., Arnold, C., Jaudszus, A., Mentzel, H., Renz, D., Reinsch, S.,…Mainz, J. (2017). Abdominal symptoms in cystic fibrosis and their relation to genotype, history, clinical and laboratory findings. PloS one , 12 (5), e0174463. Https://doi.org/10.1371/journal.-pone.0174463 .

   I enjoyed reading your post, it was very detailed and very interesting. I like how you presented the discussion. We all know by now that Cystic fibrosis is an inherited disease and the most common life-shortening autosomal recessive disease among Caucasian populations, with a frequency of 1 in 2000 to 3000 live births. The median predicted survival for CF patients in the United States was 39.3 years (95% CI, 37.3-41.4) according to the Cystic Fibrosis Foundation 2014 Registry Report (Katkin, 2020). As in your discussion, it was common in people of European descent to inherit CF (McCance & Huether, 2018).

Over the years, Cystic Fibrosis (CF) has had significant improvements for early diagnoses and better management for delayed disease progression. The treatments recently are specifically seeking ways to target the genetic mutation causing the disease (Huether & McCance, 2017). Specifically, the correction of the misprocessing of the CFTR protein is helping trial new drugs. Understanding the pathophysiology of the disease can assist in the best treatment plan. For example, Ataluren is now used in research trials, which helps restore the function of mutation in the gene and aids in correcting the chloride channel transport by targeting CFTR protein (Brown, White, & Tobin, 2017).

I wanted also to point out in response to the mother on her 23 mos. We can also educate the mom and the husband of advanced teaching to them, we can give options regarding the CF screening and the disease itself. It will be beneficial for the mother and her husband to contemplate if they choose to have another kid. Newborn screening is universal in the US.  Ideally, when a family member has confirmed CF, other family members should be screened by the same laboratory that tested the affected relative. The screening panel should include familial mutations previously identified as well as the mutations in the standard panel. Genetic counseling should also be available to them and take also into consideration. Researchers have shown that females are more likely to succumb to this disease than men. Although this gender disparity is not researched often, it has been hypothesized that the disease is hormone mediated. This could account for the 23-month-old to not show symptoms as soon as the 6-month-old (Harness-Brumley, Elliot, Rosenbluth, Raghaven, & Jain, 2014). With mother already having two children with CF, it would be beneficial for her and her partner to undergo carrier screening, if not already performed. If considering, genetic counseling would also be of assistance. If both partners are positive for the CF mutation, there are options such as accepting the risk, adoption, and in vitro fertilization, with the use of preimplantation genetic diagnosing (The American College of Obstetricians and Gynecologists, 2017). As providers, it is our responsibility to keep the patient informed upfront regarding any future pregnancies. Again, thank you for your great post.

Brown, S. D., White, R., & Tobin, P. (2017). Keep them breathing: Cystic fibrosis pathophysiology, diagnosis, and treatment. Journal of the American Academy of PAs, 30(5), 23-27. doi: 10.1097/01.JAA.0000515540.36581.92

Harness-Brumley, C.L., Elliot, A.C., Rosenbluth, D.B., & Jain, R., (2014). Gender differences

In outcomes of the patient with cystic fibrosis, Journal of Women’s Health, 23(12). Pp 1012-1020

Huether, S. E., & McCance, K. L. (2019) Pathophysiology: The biologic basis for disease in adults and child ( 8th Ed.) St. Louis, Missouri: Elsevier

Katkin, J. (2019) Cystic Fibrosis: Clinical manifestation and Diagnosis. Up to Date.

Retrieve 10 October 2019 from https//:www.uptodate.com

The American College of Obstetricians and Gynecologists. (2017, June). FAQs171. Retrieved from Women’s Health Care Physicians: https://www.acog.org/Patients/FAQs/Cystic-Fibrosis-Prenatal-Screening-and-Diagnosis?IsMobileSet=false

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Case Study: Cystic Fibrosis - CER

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Part I: A​ ​Case​ ​of​ ​Cystic​ ​Fibrosis

Dr. Weyland examined a six month old infant that had been admitted to University Hospital earlier in the day. The baby's parents had brought young Zoey to the emergency room because she had been suffering from a chronic cough. In addition, they said that Zoey sometimes would "wheeze" a lot more than they thought was normal for a child with a cold. Upon arriving at the emergency room, the attending pediatrician noted that salt crystals were present on Zoey's skin and called Dr. Weyland, a pediatric pulmonologist. Dr. Weyland suspects that baby Zoey may be suffering from cystic fibrosis.

CF affects more than 30,000 kids and young adults in the United States. It disrupts the normal function of epithelial cells — cells that make up the sweat glands in the skin and that also line passageways inside the lungs, pancreas, and digestive and reproductive systems.

The inherited CF gene directs the body's epithelial cells to produce a defective form of a protein called CFTR (or cystic fibrosis transmembrane conductance regulator) found in cells that line the lungs, digestive tract, sweat glands, and genitourinary system.

When the CFTR protein is defective, epithelial cells can't regulate the way that chloride ions pass across cell membranes. This disrupts the balance of salt and water needed to maintain a normal thin coating of mucus inside the lungs and other passageways. The mucus becomes thick, sticky, and hard to move, and can result in infections from bacterial colonization.

cystic fibrosis cer.png

Part​ ​II:​ ​ ​CF​ ​is​ ​a​ ​disorder​ ​of​ ​the​ ​cell​ ​membrane.

Imagine a door with key and combination locks on both sides, back and front. Now imagine trying to unlock that door blind-folded. This is the challenge faced by David Gadsby, Ph.D., who for years struggled to understand the highly intricate and unusual cystic fibrosis chloride channel – a cellular doorway for salt ions that is defective in people with cystic fibrosis.

His findings, reported in a series of three recent papers in the Journal of General Physiology, detail the type and order of molecular events required to open and close the gates of the cystic fibrosis chloride channel, or as scientists call it, the cystic fibrosis transmembrane conductance regulator (CFTR).

Ultimately, the research may have medical applications, though ironically not likely for most cystic fibrosis patients. Because two-thirds of cystic fibrosis patients fail to produce the cystic fibrosis channel altogether, a cure for most is expected to result from research focused on replacing the lost channel.

cystic fibrosis cer 2.png

5. Suggest a molecular fix for a mutated CFTR channel. How would you correct it if you had the ability to tinker with it on a molecular level?

6. Why would treatment that targets the CFTR channel not be effective for 2⁄3 of those with cystic fibrosis?

7. Sweat glands cool the body by releasing perspiration (sweat) from the lower layers of the skin onto the surface. Sodium and chloride (salt) help carry water to the skin's surface and are then reabsorbed into the body. Why does a person with cystic fibrosis have salty tasting skin?

Part​ ​III:​ ​No​ ​cell​ ​is​ ​an​ ​island

Like people, cells need to communicate and interact with their environment to survive. One way they go about this is through pores in their outer membranes, called ion channels, which provide charged ions, such as chloride or potassium, with their own personalized cellular doorways. But, ion channels are not like open doors; instead, they are more like gateways with high-security locks that are opened and closed to carefully control the passage of their respective ions.

In the case of CFTR, chloride ions travel in and out of the cell through the channel’s guarded pore as a means to control the flow of water in and out of cells. In cystic fibrosis patients, this delicate salt/water balance is disturbed, most prominently in the lungs, resulting in thick coats of mucus that eventually spur life-threatening infections. Shown below are several mutations linked to CFTR:

cystic fibrosis cer 3.png

8. Which mutation do you think would be easiest to correct. Justify your answer. 9. Consider what you know about proteins, why does the “folding” of the protein matter?

Part​ ​IV:​ ​Open​ ​sesame

Among the numerous ion channels in cell membranes, there are two principal types: voltage-gated and ligand-gated. Voltage-gated channels are triggered to open and shut their doors by changes in the electric potential difference across the membrane. Ligand-gated channels, in contrast, require a special “key” to unlock their doors, which usually comes in the form of a small molecule.

CFTR is a ligand-gated channel, but it’s an unusual one. Its “key” is ATP, a small molecule that plays a critical role in the storage and release of energy within cells in the body. In addition to binding the ATP, the CFTR channel must snip a phosphate group – one of three “P’s” – off the ATP molecule to function. But when, where and how often this crucial event takes place has remains obscure.

cystic fibrosis cer 4.png

10. Compare the action of the ligand-gated channel to how an enzyme works.

11. Consider the model of the membrane channel, What could go wrong to prevent the channel from opening?

12. Where is ATP generated in the cell? How might ATP production affect the symptoms of cystic fibrosis?

13. Label the image below to show how the ligand-gated channel for CFTR works. Include a summary.

cystic fibrosis cer 5.png

Part​ ​V:​ Can​ ​a​ ​Drug​ ​Treat​ ​Zoey’s​ ​Condition?

Dr. Weyland confirmed that Zoey does have cystic fibrosis and called the parents in to talk about potential treatments. “Good news, there are two experimental drugs that have shown promise in CF patients. These drugs can help Zoey clear the mucus from his lungs. Unfortunately, the drugs do not work in all cases.” The doctor gave the parents literature about the drugs and asked them to consider signing Zoey up for trials.

The​ ​Experimental​ ​Drugs

Ivacaftor TM is a potentiator that increases CFTR channel opening time. We know from the cell culture studies that this increases chloride transport by as much as 50% from baseline and restores it closer to what we would expect to observe in wild type CFTR. Basically, the drug increases CFTR activity by unlocking the gate that allows for the normal flow of salt and fluids.

In early trials, 144 patients all of whom were age over the age of 12 were treated with 150 mg of Ivacaftor twice daily. The total length of treatment was 48 weeks. Graph A shows changes in FEV (forced expiratory volume) with individuals using the drug versus a placebo. Graph B shows concentrations of chloride in patient’s sweat.

cystic fibrosis cer 6.png

14. What is FEV? Describe a way that a doctor could take a measurement of FEV.

15. Why do you think it was important to have placebos in both of these studies?

16. Which graph do you think provides the most compelling evidence for the effectiveness of Ivacafor? Defend your choice.

17. Take a look at the mutations that can occur in the cell membrane proteins from Part III. For which mutation do you think Ivacaftor will be most effective? Justify your answer.

18. Would you sign Zoey up for clinical trials based on the evidence? What concerns would a parent have before considering an experimental drug?

Part​ ​VI:​ ​Zoey’s​ ​Mutation

Dr. Weyland calls a week later to inform the parents that genetic tests show that Zoey chromosomes show that she has two copies of the F508del mutation. This mutation, while the most common type of CF mutation, is also one that is difficult to treat with just Ivacaftor. There are still some options for treatment.

In people with the most common CF mutation, F508del, a series of problems prevents the CFTR protein from taking its correct shape and reaching its proper place on the cell surface. The cell recognizes the protein as not normal and targets it for degradation before it makes it to the cell surface. In order to treat this problem, we need to do two things: first, an agent to get the protein to the surface, and then ivacaftor (VX-770) to open up the channel and increase chloride transport. VX-809 has been identified as a way to help with the trafficking of the protein to the cell surface. When added VX-809 is added to ivacaftor (now called Lumacaftor,) the protein gets to the surface and also increases in chloride transport by increasing channel opening time.

cystic fibrosis cer 7.png

In early trials, experiments were done in-vitro, where studies were done on cell cultures to see if the drugs would affect the proteins made by the cell. General observations can be made from the cells, but drugs may not work on an individual’s phenotype. A new type of research uses ex-vivo experiments, where rectal organoids (mini-guts) were grown from rectal biopsies of the patient that would be treated with the drug. Ex-vivo experiments are personalized medicine, each person may have different correctors and potentiators evaluated using their own rectal organoids. The graph below shows how each drug works for 8 different patients (#1-#8)

19. Compare ex-vivo trials to in-vitro trials.

20. One the graph, label the group that represents Ivacaftor and Lumacaftor. What is the difference between these two drugs?

21. Complete a CER Chart. If the profile labeled #7 is Zoey, rank the possible drug treatments in order of their effectiveness for her mutation. This is your CLAIM. Provide EVIDENCE​ to support your claim. Provide REASONING​ that explains why this treatment would be more effective than other treatments and why what works for Zoey may not work for other patients. This is where you tie the graph above to everything you have learned in this case. Attach a page.

Learn more from pulmonologist Sarah Chalmers, M.D.

Hello. I'm Dr. Sarah Chalmers, a pulmonologist at Mayo Clinic. In this video, we'll cover the basics of cystic fibrosis. What is it? Who gets it? The symptoms, diagnosis and treatment. Whether you're looking for answers for yourself or someone you love, we're here to give you the best information available. Cystic fibrosis is a disorder that damages your lungs, digestive tract and other organs. It's an inherited disease caused by a defective gene that can be passed from generation to generation. Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery. But in people with CF, they're thick and sticky. Instead of acting as lubricants, these secretions plug up the tubes, ducts and airways in your body. Although there is no cure for cystic fibrosis, people with this condition are generally able to live normal lives. There are many tools and techniques doctors use to help manage this complicated condition and with improvement in screening and treatments, life expectancy for those with cystic fibrosis is better than ever before.

Simply put, cystic fibrosis is a gene defect. A defect to this gene changes how a salt moves in and out of cells, resulting in thick, sticky mucus in the respiratory, digestive and reproductive systems. It's an inherited condition. A child needs to inherit one copy of the mutated gene from each parent to develop cystic fibrosis. If they only inherit one copy from one parent, they won't develop it. However, they will be a carrier of that mutated gene, so they could pass it along to their own children in the future. Because CF is an inherited disorder, family history determines your risk. Although it can occur in all races, cystic fibrosis is most common in white people of North European ancestry.

There are two kinds of symptoms associated with cystic fibrosis. The first are respiratory symptoms. Thick, sticky mucus can clog the tubes that carry air in and out of your lungs. This can trigger a persistent cough that produces thick mucus, wheezing, exercise intolerance, repeated lung infections, and inflamed nasal passages or a stuffy nose or recurrent sinusitis. The second type of symptoms are digestive. That same thick mucus that can clog your airways can also bog tubes that carry enzymes from your pancreas to your small intestine. This can result in foul-smelling or greasy stools, poor weight gain and growth, intestinal blockage, or chronic and severe constipation, which may include frequent straining while trying to pass stool. If you or your child show symptoms of cystic fibrosis or if someone in your family has CF, talk with your doctor about testing for the disease.

Since this disease is an inherited condition, reviewing your family history is important. Genetic testing may be done to see if you carry the mutated gene that triggers cystic fibrosis. A sweat test may also be conducted. CF causes higher than normal levels of salt in your sweat. Doctors will examine the levels of salt in your sweat to confirm a diagnosis.

Because this condition is passed from parent to children, newborn screening is routinely done in every state in the U.S. Early diagnosis of CF means that treatments can begin immediately. Unfortunately, there is no cure for cystic fibrosis, but proper treatment can ease your symptoms, reduce complications, and improve your quality of life. Doctors may decide that certain medications are necessary. These could include antibiotics to treat and prevent lung infections, anti-inflammatories to lessen the swelling in your airways, or mucus-thinning drugs to help expel mucus and improve lung function. Medications can also help improve digestive function. From stool softeners to enzymes, to acid-reducing drugs. Some medications can even target the gene defect that causes cystic fibrosis, aiding the faulty proteins to improve lung function and reduce salt in your sweat. Outside of medications, airway clearance techniques, also called chest physical therapy, can relieve mucus obstruction and help to reduce infection and inflammation in the airways. These techniques loosen the thick mucus in the lungs, making it easier to cough up. In some cases, doctors turn to surgery to help alleviate conditions that can arise from cystic fibrosis. For instance, nasal and sinus surgery to help you breathe, or bowel surgery to help improve digestive function. In life-threatening instances, lung transplant and liver transplant had been performed. Managing cystic fibrosis can be very complex. So consider getting treatment at a center with medical professionals trained in the disorder to evaluate and treat your condition. You can even ask your physician about clinical trials. New treatments, interventions and tests are constantly under development to help prevent, detect, and treat this disease.

Learning you or someone you know has cystic fibrosis can be incredibly challenging. It's okay to feel depressed, anxious, angry, or afraid. In time, you'll find ways to cope, find support and talk to others who are going through it too. Look to your friends and family to help manage stress and reduce anxiety. Seek professional help. Remember, physical conditions come with an emotional and mental burden. And take the time to learn about cystic fibrosis. It's a complicated, severe disorder. So don't hesitate to talk to your medical team about your questions or concerns. With the knowledge and treatment available to doctors today, life with cystic fibrosis is better than ever before. If you'd like to learn even more about cystic fibrosis, watch our other related videos or visit mayoclinic.org. We wish you well.

Normal airway versus airway with cystic fibrosis

In cystic fibrosis, the airways fill with thick, sticky mucus, making it difficult to breathe. The thick mucus is also an ideal breeding ground for bacteria and fungi.

Cystic fibrosis (CF) is an inherited disorder that causes severe damage to the lungs, digestive system and other organs in the body.

Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery. But in people with CF , a defective gene causes the secretions to become sticky and thick. Instead of acting as lubricants, the secretions plug up tubes, ducts and passageways, especially in the lungs and pancreas.

Although cystic fibrosis is progressive and requires daily care, people with CF are usually able to attend school and work. They often have a better quality of life than people with CF had in previous decades. Improvements in screening and treatments mean that people with CF now may live into their mid- to late 30s or 40s, and some are living into their 50s.

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In the U.S., because of newborn screening, cystic fibrosis can be diagnosed within the first month of life, before symptoms develop. But people born before newborn screening became available may not be diagnosed until the signs and symptoms of CF show up.

Cystic fibrosis signs and symptoms vary, depending on the severity of the disease. Even in the same person, symptoms may worsen or improve as time passes. Some people may not experience symptoms until their teenage years or adulthood. People who are not diagnosed until adulthood usually have milder disease and are more likely to have atypical symptoms, such as recurring bouts of an inflamed pancreas (pancreatitis), infertility and recurring pneumonia.

People with cystic fibrosis have a higher than normal level of salt in their sweat. Parents often can taste the salt when they kiss their children. Most of the other signs and symptoms of CF affect the respiratory system and digestive system.

Respiratory signs and symptoms

The thick and sticky mucus associated with cystic fibrosis clogs the tubes that carry air in and out of your lungs. This can cause signs and symptoms such as:

Digestive signs and symptoms

The thick mucus can also block tubes that carry digestive enzymes from your pancreas to your small intestine. Without these digestive enzymes, your intestines aren't able to completely absorb the nutrients in the food you eat. The result is often:

When to see a doctor

If you or your child has symptoms of cystic fibrosis — or if someone in your family has CF — talk with your doctor about testing for the disease. Consult a physician who is knowledgeable about CF .

Cystic fibrosis requires consistent, regular follow-up with your doctor, at least every three months. Contact you doctor if you experience new or worsening symptoms, such as more mucus than usual or a change in the mucus color, lack of energy, weight loss, or severe constipation.

Seek immediate medical care if you're coughing up blood, have chest pain or difficulty breathing, or have severe stomach pain and distention.

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In cystic fibrosis, a defect (mutation) in a gene — the cystic fibrosis transmembrane conductance regulator (CFTR) gene — changes a protein that regulates the movement of salt in and out of cells. The result is thick, sticky mucus in the respiratory, digestive and reproductive systems, as well as increased salt in sweat.

Many different defects can occur in the gene. The type of gene mutation is associated with the severity of the condition.

Children need to inherit one copy of the gene from each parent in order to have the disease. If children inherit only one copy, they won't develop cystic fibrosis. However, they will be carriers and could pass the gene to their own children.

Risk factors

Because cystic fibrosis is an inherited disorder, it runs in families, so family history is a risk factor. Although CF occurs in all races, it's most common in white people of Northern European ancestry.

Complications

Complications of cystic fibrosis can affect the respiratory, digestive and reproductive systems, as well as other organs.

Respiratory system complications

Digestive system complications

Reproductive system complications

Other complications

If you or your partner has close relatives with cystic fibrosis, you both may choose to have genetic testing before having children. The test, which is performed in a lab on a sample of blood, can help determine your risk of having a child with CF .

If you're already pregnant and the genetic test shows that your baby may be at risk of cystic fibrosis, your doctor can conduct additional tests on your developing child.

Genetic testing isn't for everyone. Before you decide to be tested, you should talk to a genetic counselor about the psychological impact the test results might carry.

Cystic fibrosis care at Mayo Clinic

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case study about cystic fibrosis

Case Studies in Pediatric Anesthesia

Book contents

Chapter 13 - Cystic Fibrosis

Published online by Cambridge University Press:  30 November 2019

This chapter reviews the pathophysiology of cystic fibrosis and its effects on a host of organ systems. The author discusses the anesthetic implications of cystic fibrosis allowing the reader to formulate a safe perioperative plan for these patients.

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Queen's University Belfast

Transforming the lives of people with Cystic Fibrosis

Stuart Elborn

Researchers from Queen’s have transformed the lives of people with Cystic Fibrosis by leading on the clinical development of treatments that address the underlying genetic disorder.

Research Challenge

80,000 people live with cystic fibrosis globally.

Cystic Fibrosis is a progressive, life-limiting genetic disease that causes severe respiratory and digestive problems as well as other complications such as infections and diabetes.

There are over 80,000 people living with Cystic Fibrosis globally, including 10,500 in the UK accounting for 9,500 hospital admissions and over 100,000 bed days per year .

The condition is caused by a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which is responsible for the regulation of salt and water levels in the body. The mutations can lead to the build-up of thick mucus in the lungs, digestive tract and other parts of the body causing persistent chest infections, resulting in lung damage and an early death.

Our Approach

Pioneering a drug development programme.

Queen’s University’s Cystic Fibrosis research team is recognised as world leading, having worked for over 12 years supporting the development of drugs that improve the function of CTFR.

Prior to their work, treatments for Cystic Fibrosis had been focused on symptom control. However, during the last decade, Queen’s University Belfast has been at the forefront of major advancements in drugs targeting the underlying genetic deficit .

This work included the development of clinical trial protocols, and inclusion of key outcome measures such as; lung function (FEV1), pulmonary exacerbation rate, and Quality of Life (QoL) tools for use in clinical trials of new therapeutics.

Extensive clinical trial experience coupled with a Clinical Trial Network infrastructure established by Queen’s and the Belfast Health and Social Care Trust, resulted in Queen’s playing a pivotal role in a drug development programme working alongside Vertex Pharmaceuticals to deliver trials for single, double and triple therapies in Cystic Fibrosis .

Working with industry, clinical trial networks and contract research organisations and colleagues at other Higher Education Institutes such as Imperial College, Queen’s University has developed expertise in the delivery of clinical trials of single and multiple combination therapies .

Their expertise in Cystic Fibrosis, and with respect to clinical trials has hugely contributed to the outstanding progress in treating this severe, life shortening disease across more than a decade of dedicated help and knowledge.

What impact did it make?

Transforming the lives of people with cystic fibrosis.

These transformative therapies improve lung health and have underpinned the regulatory approval and marketing of 4 breakthrough Cystic Fibrosis therapies . 

The most recent trials successfully demonstrated that a combination of drugs can treat up to 90% of people with Cystic Fibrosis by addressing the underlying cause of their disease. This new “triple therapy” results in a significant improvement in lung function and quality of life and reduces the frequency of chest infections.   

Both the Food and Drug Administration and the European Medicines Agency approved Trikafta (US)/Kaftrio (EU) for use in 2020. The drug was hailed as a  “landmark approval” by the FDA having an expedited approval process including Priority Review, Fast Track, Breakthrough Therapy, and orphan drug designation. 

The importance of these CFTR modulators has also been recognised by experts in the international CF community. The National Institutes of Health Director who, with colleagues, discovered the CFTR mutation in 1989 spoke about the importance of the Trikafta phase 3 trial results:

“…it has been 30 years that we've been hoping and dreaming for a day like this, where you could look at data and just absolutely - your jaw drops because it is so impressive and so good. Now we are at the point with this triple therapy where 90% of people with cystic fibrosis are going to have substantial and amazing benefit from the drug therapy...”  

The Queen’s research team has been instrumental in developing and strengthening international Cystic Fibrosis research initiatives.  Professor Stuart Elborn  was instrumental in establishing the  of which  Dr Damien Downey  is now Director. It has grown to encompass 58 research centres across 17 countries, caring for over 21,000 adult and paediatric patients, which is approximately 20% of the global population of patients with Cystic Fibrosis.

Impact related to the UN Sustainable Development Goals

Learn more about Queen’s University’s commitment to nurturing a culture of sustainability and achieving the Sustainable Development Goals (SDGs) through research and education.

UN Goal 03 - Good Health and well-being

80,000 people with Cystic Fibrosis

There are over 80,000 people living with Cystic Fibrosis globally, including 10,500 in the UK - accounting for 9,500 hospital admissions and over 100,000 bed days per year.

Treating up to 90% of people

The most recent trials successfully demonstrated that a combination of drugs can treat up to 90% of people with Cystic Fibrosis by addressing the underlying cause of their disease.

Explore more

What is cystic fibrosis, exactly, school/institute.

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Case Report

Diagnosis of cystic fibrosis in a patient of egyptian background.

Cystic fibrosis (CF) is the most common genetically inherited condition in European-derived populations. However, it is being increasingly recognised in other populations, including people of Asian, Black African and Caribbean descent. We present a case detailing the diagnosis of CF in a 12-year-old patient of Egyptian background who had been treated for difficult asthma. In doing so, we aim to highlight the importance of considering CF in all patients, regardless of ethnicity.

Cystic fibrosis (CF) is an autosomal recessive disease caused by a mutation in the CFTR (cystic fibrosis transmembrane conductance regulator) gene on chromosome 7. It affects 1 in 2500 babies born in the UK and is more common among people of European-derived populations. 1 Although previously presumed to be rare, CF is being increasingly recognised among non-Caucasian populations and is thought to be underdiagnosed in these patient groups. 2 Newborn screening for CF was introduced in the UK in 2007. However, screening will still miss a proportion of the population and vigilance must be maintained for those born prior to 2007 or born abroad who will not have been screened.

Case presentation

A boy aged 12 years presented to the tuberculosis clinic (TB) with a several year history of a chronically productive cough with associated shortness of breath and wheeze. He also reported of lethargy, night sweats and weight loss. He had been screened for TB, with a negative Mantoux test, 5 years previously. Initially, the patient had been managed by his GP who had referred him on to secondary care with suspected asthma. At this point, he was started on a budesonide with formoterol preventer inhaler (Symbicort) and terbutaline sulfate turbohaler (Bricanyl) to variable effect. Owing to his ongoing symptoms, a chest X-ray was performed which revealed bilateral hilar lymphadenopathy, resulting in a referral to the TB clinic.

Born in the UK in 2002 at 38 weeks gestation, he was the fourth infant of non-consanguineous parents of Egyptian background. He had been fully immunised, including the BCG vaccination, and had had no known TB contact. The only positive family history was of atopy. His parents report he developed a cough soon after birth which persisted for most of his life. He was first acutely unwell with a productive cough and weight loss at the age of 5 years while on holiday in Egypt. On return to the UK, he was hospitalised and improved following a course of intravenous antibiotics. It was 3 years after this episode that he was started on asthma treatment following the development of a chronic cough.

On initial examination at the TB clinic, his chest was clear on auscultation and he had several small submandibular lymph nodes. His height and weight were on the 9th centile for his age. Repeat TB investigations, including Mantoux, T-spot and sputum AFB, were negative. His sputum culture grew Staphylococcus aureus and he was treated for a lower respiratory tract infection with 2 weeks of coamoxiclav (amoxicillin with clavulanic acid).

At follow-up, he was still symptomatic with a chronically productive cough and poor appetite. Further questioning revealed abdominal pain and steatorrhoea. Examination at this point revealed finger clubbing ( figures 1 and ​ and2), 2 ), prompting further investigations into an underlying chronic respiratory condition.

An external file that holds a picture, illustration, etc. Object name is bcr2016217072f01.jpg

Clubbing of the thumbs.

An external file that holds a picture, illustration, etc. Object name is bcr2016217072f02.jpg

Finger clubbing left hand.

Investigations

High-resolution CT chest showed widespread bronchiectasis with evidence of mucus plugging ( figure 3 ). Sweat test revealed a high chloride level of 81 mmol/L, with >60 mmol/L reflecting a likely diagnosis of CF. Subsequent genetic testing confirmed CF with a c.1040G>C p mutation and Exon 14b deletion present. Lung function tests at the time of diagnosis revealed an FVC (forced vital capacity) of 73% predicted and an FEV1 (forced expiratory volume in 1 s) of 54% predicted. There was also evidence of pancreatic insufficiency, as his faecal elastase level was <15 μg.

An external file that holds a picture, illustration, etc. Object name is bcr2016217072f03.jpg

High-resolution CT chest showing bronchiectasis and mucus plugging.

Differential diagnosis

For a patient presenting with chronically productive cough, the differential diagnoses would include CF, asthma, tuberculosis, primary ciliary dyskinesia, immune deficiencies as well as gastro-oesophageal reflux disease and recurrent aspiration. Subtle signs such as finger clubbing and nasal polyps may help guide towards a diagnosis of CF.

Following the above investigations, the patient was started on regular pancreatic enzyme replacement therapy, fat-soluble vitamins, nebulised DNase and prophylactic flucloxacillin. He was also seen in the multidisciplinary CF clinic, receiving dietetic and physiotherapy input. He had his first isolation of pseudomonas several months after diagnosis which led to a 2-week admission for intravenous antipseudomonal antibiotics. Following this, he was started on regular nebulised colistimethate sodium.

Outcome and follow-up

After the initiation of treatment, the patient's long-standing symptoms, including cough and loss of appetite, improved. His weight and height increased to between the 9th and 25th centile. In addition, his lung function improved with an FVC of 89% predicted and FEV1 of 90% predicted following his admission for intravenous antipseudomonal antibiotics. He remains under regular review at the CF clinic.

In the last few decades, CF has been increasingly diagnosed in Latin America, the Middle East and in those from the Indian subcontinent. 2 There are little available data on the incidence of CF in Egypt. One of the only studies attempting to evaluate the number of patients with CF in the country was conducted in 1993 and involved over 18 000 newborns. It estimated the prevalent rate of CF in Egypt to be 1 in 2664. 3 Supporting this, a study from neighbouring Jordan estimated the incidence of CF to be 1 in 2560. 4 In a more recent study, 100 patients who were clinically suspected of having the disease were recruited for CF screening. CF was diagnosed in more than one-third of patients, suggesting that the condition may be going undetected due to a low index of suspicion. 5

The growing recognition of CF in non-Caucasian populations, as supported by these studies, has implications for how CF is viewed among clinicians. The perception of CF as a condition solely attributed to people from European-derived populations must change to reflect our current understanding. Our case reported a patient with CF who was from an Egyptian background and had the classic signs and symptoms of CF. We wanted to highlight the importance of considering CF as a differential diagnosis in people regardless of their ethnic origin.

Learning points

Contributors: Research and original writing conducted by RY. Revised by BR.

Competing interests: None declared.

Patient consent: Obtained.

Provenance and peer review: Not commissioned; externally peer reviewed.

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  1. Cystic fibrosis and survival to 40 years: a case-control study

    A case-control study of adult CF patients was used to compare long-term survivors (aged ≥40 yrs) with patients who died before reaching 30 yrs of age. Each case (n = 78) was matched by birth date with at least one control (n = 152), after exclusion of "late diagnosis" patients.

  2. Cystic fibrosis often goes under-diagnosed—unless you're white

    A study published last year in Pediatric Pulmonology revealed that genetic screening of newborns was more likely to fail to detect cystic fibrosis in non-white babies than in white ones ...

  3. Cystic Fibrosis case study

    Cystic Fibrosis case study - History of Present Problem: Justin Ewing is a seven-year-old boy with a - Studocu unfolding case study history of present problem: justin ewing is boy with history of cystic fibrosis (cf) who for the past two days has had fever of 102.1 (38.9 DismissTry Ask an Expert Ask an Expert Sign inRegister Sign inRegister Home

  4. PDF Case 12. Cystic Fibrosis

    Case 12. Cystic Fibrosis Education of the couple. Education involves having access to individuals and families dealing with CF as well as a variety of allied health professionals instrumental in treating individuals with cystic fibrosis. Many organizations and support groups are available to help families cope with the disease.

  5. Cystic fibrosis and coeliac disease: a case report of an unusual

    BACKGROUND. Coeliac disease (CD) is a malabsorption syndrome caused by gluten-induced small intestinal damage [].The signs and symptoms of CD, such as malabsorption, diarrhea, steatorrhea, and growth failure are nonspecific and may be difficult to distinguish from common symptoms of cystic fibrosis (CF) [].In 1938, Dorothy Anderson reported a syndrome which believed to be CD but described a ...

  6. Cystic Fibrosis Case Study Flashcards

    Cystic Fibrosis Case Study Term 1 / 28 Which statement by the mother supports the diagnosis of CF Click the card to flip 👆 Definition 1 / 28 When i kiss my daughter, her skin tastes like salt Click the card to flip 👆 Flashcards Learn Test Match Created by coxcyb Terms in this set (28) Which statement by the mother supports the diagnosis of CF

  7. HESI Cystic fibrosis Case Study Darla Flashcards

    HESI Cystic fibrosis Case Study Darla 4.8 (9 reviews) Term 1 / 25 1. Which statement by the mother supports the diagnosis of CF? Click the card to flip 👆 Definition 1 / 25 "When I kiss my daughter, her skin tastes like salt." Click the card to flip 👆 Flashcards Learn Test Match Created by Debbie_Rowan Teacher Terms in this set (25) 1.

  8. Case Study: Cystic Fibrosis and Mutations

    Genetics Case Study: CF Mutations Shannan Muskopf November 30, 2020 This case study is a follow-up to the Cystic Fibrosis Case Study where students explore how changes in transport proteins affects the movement of ions, resulting in a build-up of chloride ions and the symptoms of the disease.

  9. Cystic Fibrosis: Case Study

    Cystic Fibrosis: Case Study Topic: Health & Medicine Words: 1069 Pages: 4 May 17th, 2022 Cystic fibrosis (CF) is a disease caused by defective chloride transportation. The defect in chloride transportation is a result of metamorphosis within the cystic fibrosis gene leading to abnormalities of cyclic adenosine monophosphate (cAMP).

  10. Case Study: Cystic Fibrosis in the Newborn

    Cystic fibrosis (CF) is considered one of the most commonly occurring fatal genetic disorders. This disorder is associated with pancreatic insufficiency and pulmonary complications. However, at birth the initial complications are associated with bowel obstruction. Cystic fibrosis management warrants … Case Study: Cystic Fibrosis in the Newborn

  11. Case Study: Cystic Fibrosis

    Case Study - What is the Relationship Between the Cell Membrane and Cystic Fibrosis? Dr. Weyland examined a six month old infant that had been admitted to University Hospital earlier in the day. The baby's parents had brought young Zoey to the emergency room because she had been suffering from a chronic cough.

  12. Case Study cystic fibrosis.docx

    Cystic Fibrosis (CF) Case Study History of Present Illness H.M., a 3-year-old female with cystic fibrosis, presents to ER with her parents, who report increased cough productive of green sputum over the past week, increasing dyspnea. H.M. has noticeable wheezing on physical exam. Her parents report a history of fatty diarrhea and poor weight gain.

  13. Cystic Fibrosis Case Study Patient.docx

    Cystic Fibrosis Case Study Patient.docx -. School Middle Georgia State University. Course Title NURS 1110. Uploaded By justwannapassclass. Pages 3. This preview shows page 1 - 3 out of 3 pages.

  14. Cystic Fibrosis Case Study

    Cystic Fibrosis (CF) is a disease that is inherited and affects the mucus and sweat production by those glands (McCance & Huether, 2018). How it is inherited is that parents of children with CF both have to be carriers of the cystic fibrosis transmembrane regulator (CFTR) mutation gene (McCance & Huether, 2018).

  15. Gene Therapy Case Study: Cystic Fibrosis

    Genetic Science Learning Center. (2012, December 1) Gene Therapy Case Study: Cystic Fibrosis. Retrieved February 21, 2023, from https://learn.genetics.utah.edu ...

  16. Case Study: Cystic Fibrosis

    Part I: A Case of Cystic Fibrosis Dr. Weyland examined a six month old infant that had been admitted to University Hospital earlier in the day. The baby's parents had brought young Zoey to the emergency room because she had been suffering from a chronic cough.

  17. Cystic fibrosis

    Cystic fibrosis is a disorder that damages your lungs, digestive tract and other organs. It's an inherited disease caused by a defective gene that can be passed from generation to generation. Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery.

  18. Cystic Fibrosis (Chapter 13)

    This chapter reviews the pathophysiology of cystic fibrosis and its effects on a host of organ systems. The author discusses the anesthetic implications of cystic fibrosis allowing the reader to formulate a safe perioperative plan for these patients. ... Book: Case Studies in Pediatric Anesthesia; Online publication: 30 November 2019; Chapter ...

  19. Cystic Fibrosis Treatments Transforming Lives

    Cystic Fibrosis is a progressive, life-limiting genetic disease that causes severe respiratory and digestive problems as well as other complications such as infections and diabetes. There are over 80,000 people living with Cystic Fibrosis globally, including 10,500 in the UK accounting for 9,500 hospital admissions and over 100,000 bed days per ...

  20. Case study: cystic fibrosis

    Case study: cystic fibrosis Am J Med Technol. 1982 Jan;48(1):25-7. Author S A Bowling. PMID: 7072751 No abstract available. Publication types Case Reports MeSH terms Child Cystic Fibrosis / complications Cystic Fibrosis / diagnosis*

  21. National Center for Biotechnology Information

    National Center for Biotechnology Information

  22. Cystic Fibrosis Case Study

    Cystic Fibrosis Case Study - Flashcards 🎓 Get access to high-quality and unique 50 000 college essay examples and more than 100 000 flashcards and test answers from around the world! ... which rational best supports the referral to the cystic fibrosis foundation? question. document the observations, but take no action at this time.