Demographics of the UK cystic fibrosis population: implications for neonatal screening

Exploring the complexity of cystic fibrosis (CF) and psychosocial wellbeing in the 2020s: Current and future challenges

Cystic fibrosis (CF) is traditionally associated with considerable and progressive multisystem pathology, onerous treatment burden, complex psychosocial challenges, and reduced life-expectancy [1-9].This decade has seen transformative change in management for many, but not all, people with CF. The most notable change comes from Cystic Fibrosis Transmembrane Receptor (CFTR) modulators, which bring significant benefits for people who are eligible for, and able to access, them [10]. However alongside, or perhaps because of, this exciting progress, the past few years have also brought important novel challenges to the psychosocial wellbeing of people with CF. This article, written as a collaboration between CF psychologists, social workers, physicians and nurses aims to provide an accessible overview of the novel psychosocial challenges now faced by children, their families, and adults with CF, and to invite consideration of their changing psychosocial requirements to inform future holistic care. Themes include geopolitical stressors such as the pandemic and its wake, a growing divide between those able or unable to access CFTR modulators, potential rapid changes in life expectancy secondary to these drugs and the inevitable associated challenges this brings; evolving body image, mental health side effects of CFTR modulators, the challenges of adherence in apparently well children and young adults, as well as the diagnostic conundrum and associated anxiety of the cystic fibrosis screen positive inconclusive diagnosis (CFSPID) label. It also highlights some unmet research and service delivery needs in the area.

Diagnostic accuracy of ancillary tests in diagnosis of cystic fibrosis and development of cystic fibrosis clinical diagnostic score: A multicentre prospective cohort study

BACKGROUND

Diagnostic tests for cystic fibrosis (CF) are not readily available in resource-limited settings, which leads to delay in diagnosis and treatment of children with CF.

METHODS

In a multicentric prospective study, children with recurrent/persistent pneumonia, failure to thrive, or steatorrhea with suspicion of CF were enrolled. Sweat chloride concentration was measured to confirm the diagnosis of CF. Diagnostic accuracy of various clinical features, ancillary laboratory investigations (serum electrolytes, blood gas, stool fat globules), and aquagenic wrinkling for CF diagnosis was estimated. CF clinical diagnostic score (CF-CDS) was developed by combining significant parameters in stepwise logistic regression.

RESULTS

Of 860 children enrolled, 313 (36.7 %) were diagnosed with CF. History of a sibling with CF, clubbing, hyponatremia, metabolic alkalosis, stool fat globule positivity, sputum Pseudomonas isolation, and aquagenic wrinkling within 3 min were found to be independently associated with a diagnosis of CF. CF-CDS score developed by combining these parameters demonstrated excellent diagnostic accuracy for diagnosis of CF [AUROC of 0.923 (95 %CI: 0.899, 0.946)]. At a cut-off of ≥2.5, CF-CDS had sensitivity and specificity of 87.64 % and 81.02 %, respectively.

CONCLUSION

CF-CDS has excellent diagnostic accuracy for diagnosis of CF in children and can be used to decide on starting treatment of CF pending confirmatory tests when confirmatory tests are not readily available.

Cystic Fibrosis Newborn Screening: A Systematic Review-Driven Consensus Guideline from the United States Cystic Fibrosis Foundation

Newborn screening for cystic fibrosis (CF) has been universal in the US since 2010; however, there is significant variation among newborn screening algorithms. Systematic reviews were used to develop seven recommendations for newborn screening program practices to improve timeliness, sensitivity, and equity in diagnosing infants with CF: (1) The CF Foundation recommends the use of a floating immunoreactive trypsinogen (IRT) cutoff over a fixed IRT cutoff; (2) The CF Foundation recommends using a very high IRT referral strategy in CF newborn screening programs whose variant panel does not include all CF-causing variants in CFTR2 or does not have a variant panel that achieves at least 95% sensitivity in all ancestral groups within the state; (3) The CF Foundation recommends that CF newborn screening algorithms should not limit CFTR variant detection to the F508del variant or variants included in the American College of Medical Genetics-23 panel; (4) The CF Foundation recommends that CF newborn screening programs screen for all CF-causing CFTR variants in CFTR2; (5) The CF Foundation recommends conducting CFTR variant screening twice weekly or more frequently as resources allow; (6) The CF Foundation recommends the inclusion of a CFTR sequencing tier following IRT and CFTR variant panel testing to improve the specificity and positive predictive value of CF newborn screening; (7) The CF Foundation recommends that both the primary care provider and the CF specialist be notified of abnormal newborn screening results. Through implementation, it is anticipated that these recommendations will result in improved sensitivity, equity, and timeliness of CF newborn screening, leading to improved health outcomes for all individuals diagnosed with CF following newborn screening and a decreased burden on families.

CFTR Exon 10 deleterious mutations in patients with congenital bilateral absence of vas deferens in a cohort of Pakistani patients

Congenital bilateral absence of vas deferens (CBAVD) is a urological syndrome of Wolffian ducts and is responsible for male infertility and obstructive azoospermia. This study is designed to explore the integrity of exon 10 of CFTR and its role in male infertility in a cohort of CBVAD patients in Pakistan. Genomic DNA was extracted from 17 male patients with CBAVD having clinical symptoms, and 10 healthy controls via phenol-chloroform method. Exon 10 of the CFTR gene was amplified, using PCR with specific primers and DNA screening was done by Sanger sequencing. Sequencing results were analyzed using freeware Serial Cloner, SnapGene, BioEdit and FinchTV. Furthermore, bioinformatics tools were used to analyze the mutations and their impact on the protein function and stability. We have identified 4 mutations on exon 10 of CFTR in 6 out of 17 patients. Two of the mutations were missense variants V456A, K464E, and the other two were silent mutations G437G, S431S. The identified variant V456A was present in 4 of the studied patients. Whereas, the presence of K464E in our patients further weighs on the crucial importance for its strategic location to influence the gene function at post-transcriptional and protein level. Furthermore, Polyphen-2 and SIFT analyze the mutations as harmful and deleterious. The recurrence of V456A and tactically conserved locality of K464E are evidence of their potential role in CBAVD patients and in male infertility. The data can contribute in developing genetic testing and treatment of CBAVD.

Cystic fibrosis in Iceland and the high prevalence of the N1303K variant

BACKGROUND

Cystic fibrosis (CF) is most common in populations of Northern European ancestry where the F508del variant predominates. In 2020, Iceland became a member of the European Cystic Fibrosis Society Patient Registry, and we launched an epidemiological study of CF in Iceland. The study aimed to determine the prevalence and the genetic variants present in the country. Furthermore, we aimed to describe the previous and the current situation regarding lung function, infections, complications, treatment, and follow-up to understand the strengths and weaknesses of CF care in Iceland.

METHODS

This retrospective study included all individuals in Iceland with a confirmed CF diagnosis between 1955 and 2021. We conducted a medical records search for CF diagnosis codes and found 30 people with CF who were included in the study. Two hundred sixteen clinical variables were registered. A descriptive analysis of these was performed.

RESULTS

The prevalence of CF in Iceland is 0.372:10,000 inhabitants. The F508del is the most common CF transmembrane conductance regulator (CFTR) variant (46.4%), closely followed by N1303K (44.6%). Staphylococcus aureus was the most common airway pathogen, followed by Pseudomonas aeruginosa. Nasal polyps and CF-related diabetes were the most common complications. Modern CF medications, including the recent CFTR modulators, are available.

CONCLUSION

Even though Iceland has a relatively low prevalence of CF, it holds the highest known prevalence of the N1303K variant in Europe. Access to necessary treatment is satisfactory, but improvements are advisable for some aspects of the routine assessments by best practice guidelines.

Mutational spectrum of CFTR in cystic fibrosis patients with gastrointestinal and hepatobiliary manifestations

BACKGROUND

Cystic fibrosis (CF) is a rare and debilitating autosomal recessive disorder. It hampers the normal function of various organs and causes severe damage to the lungs, and digestive system leading to recurring pneumonia. Cf also affects reproductive health eventually may cause infertility. The disease manifests due to genetic aberrations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This study aimed to screen for CFTR gene variants in Pakistani CF patients representing variable phenotypes.

METHODS

Clinical exome and Sanger sequencing were performed after clinical characterization of 25 suspected cases of CF (CF1-CF25). ACMG guidelines were followed to interpret the clinical significance of the identified variants.

RESULTS

Clinical investigations revealed common phenotypes such as pancreatic insufficiency, chest infections, chronic liver and lung diseases. Some patients also displayed symptoms like gastroesophageal reflux disease (GERD), neonatal cholestasis, acrodermatitis, diabetes mellitus, and abnormal malabsorptive stools. Genetic analysis of the 25 CF patients identified deleterious variants in the CFTR gene. Notably, 12% of patients showed compound heterozygous variants, while 88% had homozygous variants. The most prevalent variant was p. (Met1Thr or Met1?) at 24%, previously not reported in the Pakistani population. The second most common variant was p. (Phe508del) at 16%. Other variants, including p. (Leu218*), p. (Tyr569Asp), p. (Glu585Ter), and p. (Arg1162*) were also identified in the present study. Genetic analysis of one of the present patients showed a pathogenic variant in G6PD in addition to CFTR.

CONCLUSION

The study reports novel and reported variants in the CFTR gene in CF patients in Pakistani population having distinct phenotypes. It also emphasizes screening suspected Pakistani CF patients for the p. (Met1Thr) variant because of its increased observance and prevalence in the study. Moreover, the findings also signify searching for additional pathogenic variants in the genome of CF patients, which may modify the phenotypes. The findings contribute valuable information for the diagnosis, genetic counseling, and potential therapeutic strategies for CF patients in Pakistan.

Vitamin D and prebiotics for intestinal health in cystic fibrosis: Rationale and design for a randomized, placebo-controlled, double-blind, 2 x 2 trial of administration of prebiotics and cholecalciferol (vitamin D3) (Pre-D trial) in adults with cystic fibrosis

Individuals with cystic fibrosis (CF) have dysfunctional intestinal microbiota and increased gastrointestinal (GI) inflammation also known as GI dysbiosis. It is hypothesized that administration of high-dose cholecalciferol (vitamin D3) together with a prebiotic (inulin) will be effective, and possibly additive or synergistic, in reducing CF-related GI and airway dysbiosis. Thus, a 2 x 2 factorial design, placebo-controlled, double-blinded, pilot and feasibility, clinical trial was proposed to test this hypothesis. Forty adult participants with CF were block-randomized into one of four groups: 1) high-dose oral vitamin D3 (50,000 IU weekly) plus oral prebiotic placebo daily; 2) oral prebiotic (12 g inulin daily) plus oral placebo vitamin D3 weekly; 3) combined oral vitamin D3 weekly and oral prebiotic inulin daily; and 4) oral vitamin D3 placebo weekly and oral prebiotic placebo. The primary endpoints included 12-week changes in the microbial bacterial communities, gut and airway microbiota richness and diversity before and after the intervention. This pilot study examined whether vitamin D3 with or without prebiotics supplementation was feasible, changed airway and gut microbiota, and reduced dysbiosis, which in turn, may improve health outcomes and quality of life of patients with CF.

Outcome data from 15 years of cystic fibrosis newborn screening in a large UK region

BACKGROUND

The West Midlands Newborn Bloodspot Screening Laboratory is one of 16 in the UK and serves two tertiary paediatric cystic fibrosis (CF) centres (Staffordshire Children's Hospital at Royal Stoke and Birmingham Children's Hospital). CF newborn bloodspot screening (NBS) in this region started in November 2006 prior to the UK national roll-out in 2007. It uses an immunoreactive trypsinogen (IRT)/DNA/IRT protocol. We report the outcomes from 15 years of CF screening.

METHODS

The West Midlands CF NBS outcomes from 1 November 2006 to 31 October 2021 were reviewed. Clinical data were also obtained for babies referred to the CF centres as 'CF suspected'.

RESULTS

1 075 161 babies were screened, with 402 referred as 'CF suspected' and 205 identified as CF carriers. Of the 'CF suspected' babies, 268 were diagnosed with CF, 33 with CF screen positive, inconclusive diagnosis (CFSPID) and 17 as a CF carrier. Any CF-related diagnosis was excluded in 67. Outcome data were not available for 17, of whom 14 had died. Eighteen children with a negative CF NBS have subsequently been diagnosed with CF, 10 had meconium ileus and 8 were true 'affected not detected', presenting with respiratory symptoms or failure to thrive. This gives the West Midlands a CF birth prevalence of 1 in 4012 live births and the NBS protocol a sensitivity of 97.1% and a positive predictive value of 66.7%.

CONCLUSIONS

This large regional data set has excellent case ascertainment and demonstrates successful performance of the CF NBS protocol, with low numbers identified as CFSPID or CF carriers.

Development and implementation of a longitudinal clinical database for down syndrome in a large pediatric specialty clinic: Methodology and feasibility

Down syndrome (DS) is a complex condition associated with multiple medical, developmental, and behavioral concerns. A prospective, longitudinal clinical database was integrated into a specialty Down Syndrome Program, with the goals of better understanding the incidence, course, and impact of co-occurring medical, neurodevelopmental, and mental health conditions in DS. We describe the process of developing the database, including a systematic approach to data collection and database infrastructure, and report on feasibility, challenges, and solutions of initial implementation. Between March 2018 and November 2021, data from 842 patients (ages 4.8 months to 26 years) was collected. Challenges included caregiver form completion as well as time and personnel required for successful implementation. With full integration into clinical visit flow, the database proved to be feasible. The database enables identification of patterns of development and health throughout the lifespan and it facilitates future data sharing and collaborative research to advance care.

Vitamin D and Prebiotics for Intestinal Health in Cystic Fibrosis: Rationale and design for a randomized, placebo-controlled, double-blind, 2 × 2 trial of administration of prebiotics and cholecalciferol (vitamin D3) (Pre-D Trial) in adults with cystic fibrosis

Individuals with cystic fibrosis (CF) have dysfunctional intestinal microbiota and increased gastrointestinal (GI) inflammation also known as GI dysbiosis. It is hypothesized that administration of high-dose cholecalciferol (vitamin D3) together with a prebiotic (inulin) will be effective, and possibly additive or synergistic, in reducing CF-related GI dysbiosis and improving intestinal functions. Thus, a 2 × 2 factorial design, placebo-controlled, double-blind, clinical trial was proposed to test this hypothesis. Forty adult participants with CF will be block-randomized into one of four groups: 1) high-dose oral vitamin D3 (50,000 IU weekly) plus oral prebiotic placebo daily; 2) oral prebiotic (12 g inulin daily) plus oral placebo vitamin D3 weekly; 3) combined oral vitamin D3 weekly and oral prebiotic inulin daily; and 4) oral vitamin D3 placebo weekly and oral prebiotic placebo. The primary endpoints will include 12-week changes in the reduced relative abundance of gammaproteobacteria, and gut microbiota richness and diversity before and after the intervention. This clinical study will examine whether vitamin D3 with or without prebiotics will improve intestinal health and reduce GI dysbiosis, which in turn, should improve health outcomes and quality of life of patients with CF.

The risk of colorectal cancer in individuals with mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene: An English population-based study

BACKGROUND

Studies have demonstrated a higher risk of developing colorectal cancer (CRC) in individuals with Cystic Fibrosis (CF), and also a potentially increased risk in carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations. Life expectancy for those with CF is rising, increasing the number at risk of developing CRC.

METHODS

The incidence of CRC amongst individuals with CF was calculated using data from CORECT-R and linked UK CF Registry and Secondary User Services (SUS) data. Crude, age-specific and age-standardised rates were compared to those without CF. The presence of CFTR mutations in individuals with CRC was assessed using 100,000 Genomes Project data.

FINDINGS

The crude incidence rate of CRC in the CF population was 0.29 per 1,000 person-years (28 cases). The CF population were significantly younger than those without (median age at CRC diagnosis 52 years versus 73 years; p<0·01). When age-adjusted, there was a 5-fold increased CRC incidence amongst individuals with CF compared to those without (SIR 5.0 95%CI 3.2-6.9). When compared to other population studies the overall prevalence of CFTR mutations in the CRC population was significantly higher than expected (p<0·01).

INTERPRETATION

CF is linked to an increased risk of CRC. The incidence of CFTR mutations in the CRC population is higher than would be expected, suggesting an association between CFTR function and CRC risk. Further research is needed to develop effective screening strategies for these populations.

FUNDING

Cancer Research UK (grants C23434/A23706 & C10674/A27140).

Going the Extra Mile: Why Clinical Research in Cystic Fibrosis Must Include Children

This is an exciting time for research and novel drug development in cystic fibrosis. However, rarely has the adage, “Children are not just little adults” been more relevant. This article is divided into two main sections. In the first, we explore why it is important to involve children in research. We discuss the potential benefits of understanding a disease and its treatment in children, and we highlight that children have the same legal and ethical right to evidence-based therapy as adults. Additionally, we discuss why extrapolation from adults may be inappropriate, for example, medication pharmacokinetics may be different in children, and there may be unpredictable adverse effects. In the second part, we discuss how to involve children and their families in research. We outline the importance and the complexities of selecting appropriate outcome measures, and we discuss the role co-design may have in improving the involvement of children. We highlight the importance of appropriate staffing and resourcing, and we outline some of the common challenges and possible solutions, including practical tips on obtaining consent/assent in children and adolescents. We conclude that it is unethical to simply rely on extrapolation from adult studies because research in young children is challenging and that research should be seen as a normal part of the paediatric therapeutic journey.

Meteorological Factors Influence the Presence of Fungi in the Air; A 14-Month Surveillance Study at an Adult Cystic Fibrosis Center

Background

Cystic fibrosis is an inherited disease that predisposes to progressive lung damage. Cystic fibrosis patients are particularly prone to developing pulmonary infections. Fungal species are commonly isolated in lower airway samples from patients with cystic fibrosis. Fungal spores are prevalent in the air.

Methods

We performed environmental air sampling surveillance at the Manchester Adult Cystic Fibrosis Centre, UK (MACFC) over a 14-month period to assess fungal growth inside and outside the CF center.

Results

Airborne counts of fungal spores peaked from May to October, both in outdoor and indoor samples. Collection of meteorological data allowed us to correlate fungal presence in the air with elevated temperatures and low wind speeds. Additionally, we demonstrated patient rooms containing windows had elevated fungal counts compared to rooms not directly connected to the outdoors.

Conclusions

This study suggests that airborne Aspergillus fumigatus spores were more abundant during the summer months of the survey period, which appeared to be driven by increased temperatures and lower wind speeds. Indoor counts directly correlated to outdoor A. fumigatus levels and were elevated in patient rooms that were directly connected to the outdoor environment via an openable window designed for ventilation purposes. Further studies are required to determine the clinical implications of these findings for cystic fibrosis patients who are predisposed to Aspergillus related diseases, and in particular whether there is seasonal influence on incidence of Aspergillus related conditions and if screening for such complications such be increased during summer months and precautions intensified for those with a known history of Aspergillus related disease.

Cystic Fibrosis Diagnosed Using Indigenously Wrapped Sweating Technique: First Large-Scale Study Reporting Socio-Demographic, Clinical, and Laboratory Features among the Children in Bangladesh A Lower Middle Income Country

Due to lack of robust data on childhood cystic fibrosis (CF) in Bangladesh we sought to evaluate their clinico-epidemiology. A cross-sectional observation was conducted adopting CF-foundation consensus-panel-diagnostic criteria in 3 tertiary-care-hospitals in Bangladesh from 2000 to 2017. Clinically suspected 95 CF-cases were subjected to sweat-chloride testing using locally-developed a fast, cheap and effective indigenously body-wrapped sweating technique measured by US-Easy Lyte-automated microprocessor-controlled analyzer marking ≥60 mmol/L as positive. Mean-age of CF-cases at disease-onset was 16.9 ± 26.6 months that significantly differed with age-at-diagnosis (P < .02). Pulmonary syndromes included chronic wet cough in 100%, respiratory distress in 90.5%, digital-clubbing in 78%, mucopurulent-sputum in 74%-cases, and crepitation in 82%. Radio-imaging revealed bronchiectasis in 60%, hyperinflation/peribronchial-thickening in 22% and, pan-sinusitis in 89%-cases. While 37% had history-of malabsorption, high-fecal-fat revealed in 53%-cases. Malnutrition prevailed as severe-underweight in 87%-cases and all CF-cases (100%) had high sweat-chloride (mean = 118 ± 53.34 mmol/L). Thus, children with pulmonary features coupled with severe malnutrition and associated radio-imaging bronchiectasis should be screened for CF with a fast, cheap and effective sweat test in resource poor settings.

Characterization of Ancestral Origin of Cystic Fibrosis of Patients with New Reported Mutations in CFTR

The incidence of cystic fibrosis (CF) and the frequency of the variants reported for CFTR depend on the population; furthermore, CF symptomatology is characterized by obstructive lung disease and pancreatic insufficiency among other symptoms, which are reliant on the individual's genotype. The Ecuadorian population is a mixture of Native Americans, Europeans, and Africans. That population admixture could be the reason for the new mutations reported in a previous study by Ruiz et al. (2019). A panel of 46 Ancestry Informative Markers was used to estimate the ancestral proportions of each available sample (12 samples in total). As a result, the Native American ancestry proportion was the most prevalent in almost all individuals, except for three patients from Guayaquil with the mutation [c.757G>A:p.Gly253Arg; c.1352G>T:p.Gly451Val] who had the highest European composition.

Preliminary national report on cystic fibrosis epidemiology in Tunisia: the actual state of affairs

AIM

To establish a preliminary national report on clinical and genetic features of cystic fibrosis (CF) in Tunisian children as a first measure for a better health care organization.

METHODS

All children with CF diagnosed by positive sweat tests between 1996 and 2015 in children's departments of Tunisian university hospitals were included. Data was recorded at diagnosis and during the follow-up from patients' medical records.

RESULTS

In 12 departments, 123 CF children were collected. The median age at diagnosis was 5 months with a median diagnosis delay of 3 months. CF was revealed mostly by recurrent respiratory tract infections (69.9%), denutrition (55.2%), and/or chronic diarrhea (41.4%). The mean sweat chloride concentration was 110.9mmol/L. At least one mutation was found in 95 cases (77.2%). The most frequent mutations were Phe508del (n=58) and E1104X (n=15). Fifty-five patients had a Pseudomonas Aeruginosa chronic colonization at a median age of 30 months. Cirrhosis and diabetes appeared at a mean age of 5.5 and 12.5 years respectively in 4 patients each. Sixty-two patients died at a median age of 8 months. Phe508del mutation and hypotrophy were associated with death (p=0.002 and p<0.001, respectively).

CONCLUSION

CF is life-shortening in Tunisia. Setting-up appropriate management is urgent.

CFTR Modulator Use Is Associated with Higher Hemoglobin Levels in Individuals with Cystic Fibrosis

RATIONALE

Understanding how cystic fibrosis transmembrane conductance regulator (CFTR) modulators influence comorbid conditions like anemia is of great interest to the cystic fibrosis community.

OBJECTIVES

To test the hypothesis that CFTR modulators are associated with higher hemoglobin (Hgb) levels.

METHODS

Annualized Hgb and other laboratory, demographic, and anthropometric data were abstracted from the U.S. CF Foundation Patient Registry for adult and pediatric registrants before and after therapy with ivacaftor (IVA) or lumacaftor/ivacaftor (LUM/IVA) between January 2010 and December 2016. Univariate and multivariate linear mixed models were used to examine the effect of IVA on Hgb in patients with G551D-CFTR, and the effect of LUM/IVA on Hgb in F508del-CFTR homozygotes. Linear regression was used to characterize change in mean Hgb over time.

RESULTS

A total of 1,347 registrants (707 males and 640 females) with G551D-CFTR and 12,582 F508del-CFTR homozygotes (6,640 males and 5,942 females) who had never undergone lung transplant and had contemporaneous data regarding Hgb and CFTR modulator use were identified. IVA was associated with average Hgb increases of 0.54 gm/dl (95% confidence interval [CI], 0.39-0.69; P < 0.0001) and 0.18 gm/dl (95% CI, 0.01-0.35; P = 0.037) for males and females, respectively, with G551D-CFTR. LUM/IVA was associated with average Hgb increases of 0.58 gm/dl (95% CI, 0.48-0.68; P < 0.0001) and 0.26 gm/dl (95% CI, 0.20-0.33; P < 0.0001) for male and female F508del-CFTR homozygotes, respectively. In multivariate models, IVA positively affected Hgb in males but not females, and LUM/IVA positively affected Hgb in both sexes.

CONCLUSIONS

IVA and LUM/IVA use are both associated with higher Hgb levels in patients with CF.

The Sweat Metabolome of Screen-Positive Cystic Fibrosis Infants: Revealing Mechanisms beyond Impaired Chloride Transport

The sweat chloride test remains the gold standard for confirmatory diagnosis of cystic fibrosis (CF) in support of universal newborn screening programs. However, it provides ambiguous results for intermediate sweat chloride cases while not reflecting disease progression when classifying the complex CF disease spectrum given the pleiotropic effects of gene modifiers and environment. Herein we report the first characterization of the sweat metabolome from screen-positive CF infants and identify metabolites associated with disease status that complement sweat chloride testing. Pilocarpine-stimulated sweat specimens were collected independently from two CF clinics, including 50 unaffected infants (e.g., carriers) and 18 confirmed CF cases. Nontargeted metabolite profiling was performed using multisegment injection-capillary electrophoresis-mass spectrometry as a high throughput platform for analysis of polar/ionic metabolites in volume-restricted sweat samples. Amino acids, organic acids, amino acid derivatives, dipeptides, purine derivatives, and unknown exogenous compounds were identified in sweat when using high resolution tandem mass spectrometry, including metabolites associated with affected yet asymptomatic CF infants, such as asparagine and glutamine. Unexpectedly, a metabolite of pilocarpine, used to stimulate sweat secretion, pilocarpic acid, and a plasticizer metabolite from environmental exposure, mono(2-ethylhexyl)phthalic acid, were secreted in the sweat of CF infants at significantly lower concentrations relative to unaffected CF screen-positive controls. These results indicated a deficiency in human paraoxonase, an enzyme unrelated to mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) and impaired chloride transport, which is a nonspecific arylesterase/lactonase known to mediate inflammation, bacterial biofilm formation, and recurrent lung infections in affected CF children later in life. This work sheds new light into the underlying mechanisms of CF pathophysiology as required for new advances in precision medicine of orphan diseases that benefit from early detection and intervention, including new molecular targets for therapeutic intervention.

Cystic Fibrosis: A Novel Pharmacologic Approach to Cystic Fibrosis Transmembrane Regulator Modulation Therapy

Therapy for cystic fibrosis (CF) has progressed during the past several decades. Much of this progress is because of advances in genetic testing to precisely identify the underlying cause of CF transmembrane regulator (CFTR) dysfunction. However, with more than 1900 mutations that can produce a faulty CFTR, the management of CF can remain a challenge. Several innovative drugs recently approved by the Food and Drug Administration, termed genetic modulators, target the underlying disease by modulating the CFTR defect. This review provides physicians with an established simple classification scheme to guide their use of these drugs. The treatment challenge of 1900 CFTR mutations has been simplified into 6 physiologic classes, each paired with an available therapy to offer patients the most functional improvement. Drug therapy monitoring, adverse effects, and indications for discontinuation must also be considered.

Genetic Testing in the Diagnosis of Primary Ciliary Dyskinesia: State-of-the-Art and Future Perspectives

Primary ciliary dyskinesia (PCD) is a heterogeneous autosomal recessive condition affecting around 1:15,000. In people with PCD, microscopic motile cilia do not move normally resulting in impaired clearance of mucus and debris leading to repeated sinopulmonary infection. If diagnosis is delayed, permanent bronchiectasis and deterioration of lung function occurs. Other complications associated with PCD include congenital heart disease, hearing impairment and infertility. A small number of longitudinal studies suggest that lung function deteriorates before diagnosis of PCD but may stabilise following diagnosis with subsequent specialist management. Early diagnosis is therefore essential, but for a number of reasons referral for diagnostic testing is often delayed until older childhood or even adulthood. Functional diagnostic tests for PCD are expensive, time consuming and require specialist equipment and scientists. In the last few years, there have been considerable developments to identify genes associated with PCD, currently enabling 65% of patients to be identified by bi-allelic mutations. The rapid identification of new genes continues. This review will consider the evidence that early diagnosis of PCD is beneficial. It will review the recent advances in identification of PCD-associated genes and will discuss the role of genetic testing in PCD. It will then consider whether screening for PCD antenatally or in the new born is likely to become a feasible and acceptable for this rare disease.

Cystic fibrosis of pancreas and nephrotic syndrome: a rare association

Cystic fibrosis (CF) is a genetic disease with autosomal recessive inheritance and is common in Caucasian people. The prevalence of this disease is between 1/2,000 and 1/3,500 live births, and the incidence varies between populations. Although the CF transmembrane conductance regulator gene is expressed in the kidneys, renal involvement is rare. With advances in the treatment of CF, life expectancy has increased, and some previously unobserved disease associations are now seen in patients with CF. It is important to follow patients with CF for possible abnormalities that may accompany CF. In this paper, we present two rare cases of CF accompanied by nephrotic syndrome.

The effect of design on the usability and real world effectiveness of medical devices: a case study with adolescent users

Adolescents are currently overlooked in many fields of healthcare research and as a result are often required to use medical devices that have been designed for use by either children or adults. This can lead to poor adherence and a reduction in health outcomes. This study examines the role of device design in the real-world effectiveness of a medical device used in the treatment of cystic fibrosis from the perspective of adolescent users. Interactive design interviews were carried out with 20 adolescent users of the acapella(®) physiotherapy device to investigate user requirements and themes about the user-device relationship that are important to this user group. This study found that adolescent users of the acapella(®) device do not use the device as regularly and correctly as is recommended by clinicians. A number of aspects of the current design of the acapella(®) device were identified that affect how and how often it is used. Five factors are identified that may improve the real world effectiveness of the acapella(®) device for adolescents with Cystic Fibrosis: engagement, information, confidence, aesthetics and compatibility with lifestyle.

Birth prevalence of disorders detectable through newborn screening by race/ethnicity

PURPOSE

The purpose of this study was to describe the birth prevalence of genetic disorders among different racial/ethnic groups through population-based newborn screening data.

METHODS

Between 7 July 2005 and 6 July 2010 newborns in California were screened for selected metabolic, endocrine, hemoglobin, and cystic fibrosis disorders using a blood sample collected via heel stick. The race and ethnicity of each newborn was self-reported by the mother at the time of specimen collection.

RESULTS

Of 2,282,138 newborns screened, the overall disorder detection rate was 1 in 500 births. The disorder with the highest prevalence among all groups was primary congenital hypothyroidism (1 in 1,706 births). Birth prevalence for specific disorders varied widely among different racial/ethnic groups.

CONCLUSION

The California newborn screening data offer a unique opportunity to explore the birth prevalence of many genetic disorders across a wide spectrum of racial/ethnicity classifications. The data demonstrate that racial/ethnic subgroups of the California newborn population have very different patterns of heritable disease expression. Determining the birth prevalence of these disorders in California is a first step to understanding the short- and long-term medical and treatment needs faced by affected communities, especially those groups that are impacted by more severe disorders.

Iron homeostasis during cystic fibrosis pulmonary exacerbation

BACKGROUND

Hypoferremia is a marker of disease severity in cystic fibrosis (CF). The effect of systemic antibiotics on iron homeostasis during CF pulmonary exacerbation (CFPE) is unknown. Our central hypotheses were that, by the completion of treatment, serum iron would increase, serum concentrations of interleukin-6 (IL-6) and hepcidin-25, two mediators of hypoferremia, would decrease, and sputum iron would decrease.

METHODS

Blood and sputum samples were collected from 12 subjects with moderate-to-severe CF (median percentage-predicted forced expiratory volume in 1 second (FEV(1) %) = 29%; median weight = 56 kg) within 24 hours of starting and completing a course of systemic antibiotics.

RESULTS

After treatment, subjects showed median FEV(1) % and body weight improvements of 4.5% and 2.0 kg, respectively (p < 0.05). Median serum iron rose by 2.4 μmol/L (p < 0.05), but 75% of patients remained hypoferremic. Median serum IL-6 and hepcidin-25 levels fell by 12.1 pg/mL and 37.5 ng/mL, respectively (p < 0.05). Median serum erythropoietin (EPO) and hemoglobin levels were unaffected by treatment. We observed a trend toward lower sputum iron content after treatment.

CONCLUSIONS

Hypoferremia is a salient characteristic of CFPE that improves with waning inflammation. Despite antibiotic treatment, many patients remain hypoferremic and anemic because of ineffective erythropoiesis.

From a single whole exome read to notions of clinical screening: primary ciliary dyskinesia and RSPH9 p.Lys268del in the Arabian Peninsula

Primary ciliary dyskinesia (PCD) is a genetic disorder, usually autosomal recessive, causing early respiratory disease and later subfertility. Whole exome sequencing may enable efficient analysis for locus heterogeneous disorders such as PCD. We whole-exome-sequenced one consanguineous Saudi Arabian with clinically diagnosed PCD and normal laterality, to attempt ab initio molecular diagnosis. We reviewed 13 known PCD genes and potentially autozygous regions (extended homozygosity) for homozygous exon deletions, non-dbSNP codon, splice-site base variants or small indels. Homozygous non-dbSNP changes were also reviewed exome-wide. One single molecular read representing RSPH9 p.Lys268del was observed, with no wild-type reads, and a notable deficiency of mapped reads at this location. Among all observations, RSPH9 was the strongest candidate for causality. Searching unmapped reads revealed seven more mutant reads. Direct assay for p.Lys268del (MboII digest) confirmed homozygosity in the affected individual, then confirmed homozygosity in three siblings with bronchiectasis. Our finding in southwest Saudi Arabia indicates that p.Lys268del, previously observed in two Bedouin families (Israel, UAE), is geographically widespread in the Arabian Peninsula. Analogous with cystic fibrosis CFTR p.Phe508del, screening for RSPH9 p.Lys268del (which lacks sentinel dextrocardia) in those at risk would help in early diagnosis, tailored clinical management, genetic counselling and primary prevention.

Understanding protein kinase CK2 mis-regulation upon F508del CFTR expression

We review areas of overlap between nucleoside diphosphate kinase (NDPK; nm23) and two proteins manifesting an equivalent diversity of action, each with many thousands of publications. The first is a constitutively active protein kinase, CK2 (formerly casein kinase 2), that includes NDPK amongst its hundreds of targets. The second is an enigmatic member of the ATP-binding cassette (ABC) family of membrane pumps that normally hydrolyse ATP to transport substrates. Yet our unusual family member (ABCC7) is not a pump but, uniquely, acts as a regulated anion channel. ABCC7 is the cystic fibrosis transmembrane conductance regulator (CFTR), and we discuss the highly prevalent CFTR mutation (F508del CFTR) in terms of the uncertainties surrounding the molecular basis of cystic fibrosis that cloud approaches to corrective therapy. Using lysates from cells stably expressing either wild-type or F508del CFTR, incubated with the CK2 substrate GTP, we show that the phosphoproteome of F508del CFTR-expressing cells both differs from wild-type CFTR-expressing cells and is significantly enhanced in intensity by ∼1.5-fold (p < 0.05, paired t test with Bonferroni correction, n = 4). Phosphorylation is about 50% attenuated with a specific CK2 inhibitor. We propose that a new function may exist for the CFTR region that is commonly mutated, noting that its sequence (PGTIKENIIF₅₀₈GVSYDEYRYR) is not only highly conserved within the C sub-family of ABC proteins but also a related sequence is found in NDPK. We conclude that a latent path may exist between mutation of this conserved sequence, CK2 hyperactivity and disease pathogenesis that might also explain the heterozygote advantage for the common F508del CFTR mutant .

A methodology to establish a database to study gene environment interactions for childhood asthma

BACKGROUND

Gene-environment interactions are likely to explain some of the heterogeneity in childhood asthma. Here, we describe the methodology and experiences in establishing a database for childhood asthma designed to study gene-environment interactions (PAGES--Paediatric Asthma Gene Environment Study).

METHODS

Children with asthma and under the care of a respiratory paediatrician are being recruited from 15 hospitals between 2008 and 2011. An asthma questionnaire is completed and returned by post. At a routine clinic visit saliva is collected for DNA extraction. Detailed phenotyping in a proportion of children includes spirometry, bronchodilator response (BDR), skin prick reactivity, exhaled nitric oxide and salivary cotinine. Dietary and quality of life questionnaires are completed. Data are entered onto a purpose-built database.

RESULTS

To date 1045 children have been invited to participate and data collected in 501 (48%). The mean age (SD) of participants is 8.6 (3.9) years, 57% male. DNA has been collected in 436 children. Spirometry has been obtained in 172 children, mean % predicted (SD) FEV1 97% (15) and median (IQR) BDR is 5% (2, 9). There were differences in age, socioeconomic status, severity and %FEV1 between the different centres (p≤0.024). Reasons for non-participation included parents not having time to take part, children not attending clinics and, in a small proportion, refusal to take part.

CONCLUSIONS

It is feasible to establish a national database to study gene-environment interactions within an asthmatic paediatric population; there are barriers to participation and some different characteristics in individuals recruited from different centres. Recruitment to our study continues and is anticipated to extend current understanding of asthma heterogeneity.

Cystic fibrosis across Europe: EuroCareCF analysis of demographic data from 35 countries

BACKGROUND

A 35-country European cystic fibrosis (CF) demographic registry was developed to compare outcomes (EuroCareCF EC-FP6).

METHODS

We applied methods that had successfully created country-specific registries inviting wide participation to obtain consent and collate demographic and CFTR genotype data.

RESULTS

Among 29,095 patients, a widely different country-specific prevalence of childhood CF exists that cannot be explained by differential population frequency of mutant-CFTR or case under-ascertainment with a significant paucity of the homozygous p.Phe508del genotype that presents in childhood in >90% of cases.

CONCLUSIONS

Excess premature childhood CF mortality may still occur. The better resourced Western Europe now has a ~5% mortality for childhood CF, which is not apparent in many of the European countries reported here. In addition, a female survival disadvantage exists. The reasons require further investigation. We showcase the value of simple data collection in one rare disease, which might interest those managing rare diseases across the globe.

The how (and why) of disease registers

A disease register is central to the understanding of clinical outcomes but the principles underpinning register design are not always apparent. My group developed, implemented and analysed outcomes using cystic fibrosis (CF) registers in Scotland (~500 patients, 1992-1995), the UK (~7000 patients, 1995-2006) and more recently across Europe (~30 000 patients, 2006-2009). The key design principles are summarised and exemplified using the process required to add new diseases such as CF to neonatal screening programmes to illustrate pitfalls in the complex path from screening to timely entry into specialist CF care. The disciplines of screening and specialist CF disease therapy are very different and our findings may be relevant for the evaluation of the fragile links in the complex patient journey. Should these links fail, they have the potential to delay the entry of a screened baby into therapy after testing positive for a preventable disease.

Cystic fibrosis in India

Cystic fibrosis (CF) was considered to be non-existent in Indian subcontinent. Reports in last one decade have suggested that cystic fibrosis occurs in India but its precise magnitude is not known. Studies on migrant Indian population in United States and United Kingdom estimate frequency of CF as 1:10,000 to 1:40,000. The clinical features are similar to that reported in Caucasian population. CF in Indian children is usually diagnosed late and in advanced stage. Children are more malnourished and may have clinically evident deficiency of fat soluble vitamins. The frequency of clubbing, colonization with Pseudomonas, and laboratory evidence of pseudo-Bartter syndrome is relatively more at the time of diagnosis. Diagnostic facilities in form of sweat chloride estimation and genetic studies are not available readily. Mutation profile is different. The frequency of common mutation F508del in Indian children is between 19% and 34%. Other mutations are heterogeneous. Management of CF in India is difficult due to less number of trained manpower, limited availability, and high cost of pharmacologic agents. The determinants of early death include: severe malnutrition and colonization with Pseudomonas at the time of diagnosis, more than four episodes of lower respiratory infection per year and age of onset of symptoms before 2 months of age. To conclude, CF does occur in India; however, precise magnitude of problem is not known. There is need to create awareness amongst pediatricians, developing diagnostic facilities, and management protocols based on locally available resources.

A global perspective on newborn screening for cystic fibrosis

PURPOSE OF REVIEW

Cystic fibrosis screening in newborns is occurring in an increasing number of countries, but protocols vary across regions, borders and continents. This review describes recent advances in the rationale for newborn screening and then suggests solutions to the hurdles that need to be overcome by clinicians to ensure long-term clinical outcomes can be measured robustly whilst retaining the confidence of the funding authorities who have many calls on limited budgets. The review is written to address the concerns of the sceptics.

RECENT FINDINGS

Beneficial evidence for screening for cystic fibrosis in newborns is accumulating and will be highlighted to aid those about to introduce screening for cystic fibrosis in competition with other diseases. Future approaches are described to minimize the amount of DNA-based information held but without compromising screening efficacy. Finally, guidelines for a pilot dataset of information that must be collected on each screened infant will be proposed.

SUMMARY

Standardization of international programs for newborns has not yet been achieved. Progress towards this goal is being made but many differences remain. Solutions to the practical difficulties of implementation of screening for newborns are described to help cystic fibrosis clinicians convince their colleagues of the merits of this practice.

Characterisation of mutations and genotype-phenotype correlation in cystic fibrosis: experience from India

BACKGROUND

Very little is known about the genetics of cystic fibrosis (CF) from the Indian subcontinent. The aims of the study were to identify the mutations and study the relation of genotype with phenotype in Indian children with CF.

METHODS

A total of 100 patients with CF were screened for mutations in the CFTR gene. These included c.1521_1523delCTT (p.F508del) and c.3849+10 kb C>T mutations followed by single strand conformation polymorphism/heteroduplex analysis for mutations in 19 out of 27 exons of the CFTR gene.

RESULTS

At least one mutation was identified in 40 patients. The most common mutation identified was p.F508del; 20 patients were homozygous and 13 heterozygous. In addition, c.3849+10 kb C>T, c.1161delC, and p.S549N were identified in two patients each and p.R352Q, p.R1158X and p.R75Q were identified in one patient each. Three novel mutations, viz. c.1002-7_1002-5delTTT, p.G149X and p.L183I were also identified. Majority of patients who were p.F508del positive originated from Pakistan and north-western states of India. The phenotypes of all patients were classical. Genotype-phenotype correlation revealed that p.F508del positive patients had a more severe disease, manifesting at an earlier age.

CONCLUSIONS

A strategy for mutation screening for CF in India must involve testing for p.F508del followed by c.1161delC, c.3849+10 kb C>T and p.S549N. There is a need for large multicentric studies using more sensitive techniques for the identification of mutations in Indian CF patients.

Genetic screening for cystic fibrosis: An overview of the science and the economics

The aim of this paper is to provide an overview of the current scientific and economic thinking on the use of genetic technologies for cystic fibrosis (CF) screening. The paper takes a public health genetics viewpoint and gives an overview of the genetics behind CF, then describes current practices in screening for the disease. We then discuss the current literature on the economic evaluations of screening for CF. As the "wet" science improves, there are direct implications for health service. Therefore, it is important to keep examining both clinical practice and economics behind the technologies.

Economic implications of newborn screening for cystic fibrosis: a cost of illness retrospective cohort study

BACKGROUND

Newborn screening for cystic fibrosis might not be introduced if implementation and running costs are perceived as prohibitive. Compared with clinical diagnosis, newborn screening is associated with clinical benefit and reduced treatment needs. We estimate the potential savings in treatment costs attributable to newborn screening.

METHODS

Using the UK Cystic Fibrosis Database, we used a prevalence strategy to undertake a cost of illness retrospective snapshot cohort study. We estimated yearly costs of long-term therapies and intravenous antibiotics for 184 patients who were diagnosed as a result of screening as newborn babies, and 950 patients who were clinically diagnosed aged 1-9 years in 2002. Costs of adding cystic fibrosis screening to an established newborn screening service in Scotland were adjusted to 2002 prices and applied to the UK as a whole. Costs were recalculated in US$.

FINDINGS

Cost of therapy for patients diagnosed by newborn screening was significantly lower than equivalent therapies for clinically diagnosed patients: mean ($7228 vs $12 008, 95% CI of difference -6736 to -2028, p<0.0001) and median ($352 vs $2442, -1916 to -180, p<0.0001). When we limited the clinically diagnosed group to only those diagnosable with a 31 cystic fibrosis transmembrane regulator mutation assay and assumed similar disease progression in the clinically diagnosed group as in the newborn screening group, we showed that mean ($3,397,344) or median ($947,032) drug cost savings could have offset the estimated cost of adding cystic fibrosis to a UK national newborn screening service ($2,971,551).

INTERPRETATION

Including indirect costs savings, newborn screening for cystic fibrosis might have even greater financial benefits to society than our estimate shows. Clinical, social, and now economic evidence suggests that universal newborn screening programmes for cystic fibrosis should be adopted internationally.

Paediatric Northern Score centile charts for the chest radiograph in cystic fibrosis

AIM

To create the first national centile charts for the chest radiograph Northern Score using the UK Cystic Fibrosis (CF) Database (UKCFD).

MATERIALS AND METHODS

All active patients for 2002 from the UKCFD were analysed in 1-year cohorts from 0 to 18 years. Northern Score results from the annual review forms were used to construct centile lines for the 5th, 25th, 50th, 75th, 95th centiles.

RESULTS

There were 1806 patients with recorded Northern Score data for 2002 (927 male patients, male:female ratio 1.05). The centile chart demonstrates a quasi-linear rise throughout childhood. A Northern Score in excess of age in years equates to >95th centile in school-aged CF patients.

CONCLUSION

This centile chart provides a disease-specific reference range for monitoring individual patients or for evaluating therapeutic change using the dominant chest radiograph scoring system in the UK. Patients, parents and clinicians may find these useful during the annual review process.

Cystic fibrosis diagnosed after 2 months of age leads to worse outcomes and requires more therapy

OBJECTIVE

Newborn screening for cystic fibrosis remains controversial because improved pulmonary function has not been established. Studies to date have not accounted for differences in treatments delivered to clinically diagnosed children and newborn-screened controls. Here, we compare outcomes and treatment of patients clinically diagnosed within the newborn-screening reporting window (early-clinically diagnosed), those presenting after this period (late-clinically diagnosed), and patients diagnosed by newborn screening.

PATIENTS AND METHODS

In a cross-sectional analysis of cohorts retrospectively ascertained, patients who were homozygous deltaF508 with cystic fibrosis, attending specialist cystic fibrosis centers, and 1 to 10 years of age between 2000 and 2002 were identified from the United Kingdom Cystic Fibrosis Database and stratified into newborn-screened, early-clinically diagnosed, or late-clinically diagnosed cohorts. Two analyses were performed: (1) after restricting to the most recent year of data collection, early-clinically diagnosed and late-clinically diagnosed cohorts were matched to newborn-screened patients by patient age and year of data collection (133 patients per cohort were identified); and (2) for all years of data collection, annual sets of data for early-clinically diagnosed and late-clinically diagnosed patients were matched to newborn-screened patients by patient age and year of data collection (291 data sets per cohort were identified). Median height and weight z scores, proportion of patients with height and weight <10th percentile, prevalence of chronic Pseudomonas aeruginosa infection, Shwachman-Kulczyki morbidity scores, percent predicted forced expiratory volume in 1 second, and numbers of long-term therapies were compared.

RESULTS

In both analyses, newborn screening was associated with higher height z score, higher Shwachman-Kulczyki score, lower likelihood of height <10th percentile, and fewer long-term therapies compared with late-clinically diagnosed patients. No other differences were found.

CONCLUSIONS

Newborn screening was associated with improved growth, reduced morbidity, and reduced therapy, yet generated equivalent pulmonary outcome compared with late clinical diagnosis, suggesting that newborn screening may slow cystic fibrosis lung disease progression.

Light and alcohol evoked electro-oculograms in cystic fibrosis

Cystic fibrosis (CF) is caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) which is a chloride channel. CFTR is expressed in the retinal pigment epithelium (RPE) where it is believed to be important in generating the fast oscillations (FOs) and potentially contributing to the light-electro-oculogram (EOG). The role of CFTR in the alcohol-EOG is unknown. We recruited six individuals with CF (three homozygotes for Delta508 and three heterozygous for Delta508) and recorded the light- and alcohol-EOGs as well as the FOs and compared them to a control group. The results showed that in the CF group the amplitude of the alcohol- and light-EOGs were normal. However, the time to peak of the light- and alcohol-rises were significantly faster than in the control group. We conclude that CFTR is not primarily responsible for the alcohol- or light-rises but is involved in altering the timing of these responses. The FOs showed differences between the homozygotes, heterozygotes and the controls. The amplitudes were significantly higher and the time to the dark troughs were significantly slower in the heterozygote group compared to both controls and the homozygotes. In contrast, the homozygotes did not differ in either amplitude or the timing of the FOs compared to the controls.

Comprehensive genetic analysis of the cystic fibrosis transmembrane conductance regulator from dried blood specimens – Implications for newborn screening

PURPOSE

In the United States, approximately 1/3,700 babies is born with cystic fibrosis each year. The >1,300 documented sequence variants pose a challenge for detection of cystic fibrosis through genetic screening. To investigate whether comprehensive characterization of the cystic fibrosis gene is feasible using dried newborn blood specimens, we modified the whole blood Ambry Test: CF and determined its sensitivity by testing DNA from individuals with cystic fibrosis who still had unknown mutations after commercial mutation panel testing.

METHODS

DNA from 42 archived newborn dried blood specimens of affected Hispanic, African-American and Caucasian individuals in California was analyzed by temporal temperature gradient electrophoresis screening and targeted sequencing, and by gross deletion analysis.

RESULTS

Excluding two specimens that could not be analyzed due to poor DNA quality, we report a 100% sensitivity and clinical detection rate in the remaining 40 patients. Eighty-three mutations representing 40 different variants were detected, including 8 novel mutations.

CONCLUSIONS

This study demonstrates the feasibility of temporal temperature gradient electrophoresis-based full sequence analysis and targeted sequencing from DNA in newborn blood specimens. The Ambry Test: CF, as an additional step in cystic fibrosis newborn screening models, can be used to dramatically reduce the number of cystic fibrosis carrier sweat test referrals.

Delayed diagnosis of females with respiratory presentation of cystic fibrosis did not segregate with poorer clinical outcome

OBJECTIVE

Does a delay in diagnosis exist in females with cystic fibrosis (CF) presenting with respiratory symptoms alone. Does it segregate with poorer clinical outcomes?

STUDY DESIGN AND SETTING

A set of 3,851 patients registered with the UK CF Database (diagnosed 1986-2003) were divided into four mutually exclusive categories by mode of presentation: meconium ileus or distal intestinal obstruction syndrome (MI/DIOS); positive family history; newborn screening; and symptoms excluding MI/DIOS. The last symptom category was subdivided to create a group for respiratory symptoms alone.

RESULTS

Females presenting with respiratory symptoms alone were diagnosed 9 months later than males (median age of diagnosis in males 22 months, n = 325; females, 31 months, n = 322; P = .028). No gender differences were observed for anthropometric, lung function, microbiological, supplemental feeding, or time since diagnosis using discriminant analysis applied to all patients (n = 461, Wilks' lambda = .97, P = .15) or to patients divided by genotype: DeltaF508/DeltaF508 (n = 168, Wilks' lambda = .97, P = .69), class I-III genotype (n = 251, Wilks' lambda = .96, P = .41), or class IV-V genotype (n = 73, Wilks' lambda = .90, P = .50) presenting with respiratory symptoms alone.

CONCLUSIONS

A relative delay in diagnosis exists in female patients presenting with respiratory symptoms alone compared with males. This does not, however, segregate with a significantly poorer clinical phenotype in the UK.

Newborn screening for cystic fibrosis: do we need a second IRT?

Commentary on the paper by Massie et al (see page 222)

Growth and lung function in Asian patients with cystic fibrosis

BACKGROUND

The incidence of cystic fibrosis (CF) in Asians is rare. How these patients fare in terms of morbidity and mortality in the UK compared to their non-Asian peers is not well documented.

AIMS

To retrospectively study annual reviews of 31 Asian CF patients from three London paediatric CF centres.

METHODS

Disease severity was assessed by lung function, age at first infection with Pseudomonas aeruginosa, and body mass index (BMI). The Asian children were compared with 143 matched non-Asian patients with CF. Matching criteria used were same sex and treatment centre as the Asian index patient. In addition, the controls were matched so that their date of birth, date of diagnosis, and date at annual review were within 12 months of the index patient.

RESULTS

There was no significant difference in age at diagnosis or age at annual review between the Asian and non-Asian children. Mean Z-scores for FEV1 and FVC were significantly lower for the Asian girls. There was no significant difference in Z-scores for BMI between the Asian children and their controls. Age at first isolation of Pseudomonas aeruginosa in Asian girls was significantly later than for their controls (8.3 years compared to 5.6 years for non-Asian girls).

CONCLUSIONS

While the Asian boys' lung function seems comparable with that of their non-Asian peers, the Asian girls emerge as a potentially vulnerable group and more work is required to discover why this is the case.

Newborn screening for cystic fibrosis is associated with reduced treatment intensity

OBJECTIVES

To determine whether the improved clinical status after newborn screening (NBS) for cystic fibrosis (CF) segregates with increased therapeutic intervention compared with presentation by clinical diagnosis (CD).

STUDY DESIGN

In 2002, two populations (1 to 9 years of age) who presented (excluding meconium ileus) by NBS < or = 3 months of age or by CD were compared in an observational, cross-sectional design. NBS and CD populations (184 and 950 patients, respectively) were divided into 3-year age groups (1 to 3, 4 to 6, and 7 to 9 years). Therapies of duration >3 months were compared together with Pseudomonas aeruginosa infection status.

RESULTS

NBS patients < or = 6 years of age received significantly fewer and less demanding therapies not explained by age, genotype, geography, or social deprivation. In 7- to 9-year-olds, significantly fewer NBS patients received intravenous antibiotics. NBS patients without P aeruginosa infection received significantly fewer therapies, but no differences were found between intermittently or chronically infected NBS and CD populations. Comparable results were found in deltaF508/deltaF508 subpopulations.

CONCLUSIONS

CF populations diagnosed by NBS are associated with reduced treatment compared with age- and genotype-matched CD control subjects.

Neonatal screening for cystic fibrosis is beneficial even in the context of modern treatment

OBJECTIVES

To determine whether early identification of babies with cystic fibrosis (CF) improves outcome in the current environment of new improved treatments, considering the criticism that there may be only marginal benefit gained by CF newborn screening (NBS).

STUDY DESIGN

We tested whether CF NBS in the setting of modern CF center care still afforded benefit using the UK CF Database (UKCFD; ) to compare clinical outcomes in infants who underwent NBS and control subjects who were clinically diagnosed (CD). With Mann-Whitney rank tests, 184 patients who underwent NBS aged 1 to 9 years in 2002 (excluding meconium ileus) were compared with matched patients who were CD in 3-year age groups (950 control subjects).

RESULTS

Patients as old as 6 years who underwent NBS had significantly greater median height z-scores, less severe Northern chest radiography scores, better Shwachman-Kulczycki scores, and lower rates of chronic Pseudomonas aeruginosa infection. No difference was found for weight z-score or % predicted forced expiratory value in 1 second or forced volume capacity. Nutritional benefit was demonstrated in patients who underwent NBS and were homozygous for the DeltaF508 mutation.

CONCLUSIONS

NBS segregates with better outcomes in patients as old as 6 years compared with age- and gene-matched control subjects who are CD. This cross-sectional study shows that infants who undergo screening derive nutritional benefit in improved median height and reduced morbidity.

Asians with cystic fibrosis in the UK have worse disease outcomes than clinic matched white homozygous delta F508 controls

BACKGROUND

We tested the hypothesis that the Asian cystic fibrosis (CF) phenotype is comparable to the commonest genetic form of CF found in 50% of the white UK CF population using the UK CF Database, a national disease-specific patient registry.

METHODS

50 Asian CF patients were matched by Centre with 143 white homozygous delta F508 patients for gender, age and chronic Pseudomonas aeruginosa status (a marker of morbidity). The authors compared FEV1 and FVC% predicted, mean height, weight and BMI Z scores.

RESULTS

FVC% predicted, weight and BMI Z scores were significantly worse in the Asians. Asian male/female FVC% predicted (p-value, 95% CI) -15.1 (p=0.001, -24.0, -8.8)/-15.2 (p=0.014, -27.1, -3.3) compared with white controls. Asian females also had significantly worse FEV1% predicted compared with controls (-14.9, p=0.025, 95% CI: -27.8, -2.0). Asians had significantly lower raw Z scores for weight (males p=0.002, females p=0.013) and BMI (males p=0.002, females p=0.008).

CONCLUSIONS

These data suggest that the Asian CF phenotype is as severe as the white controls with the homozygous delta F508 phenotype but is worse in some outcomes, especially in Asian females. Socio-cultural factors and rare CF genotypes may contribute to the severity of CF in this vulnerable group.