CFTR-France, a national relational patient database for sharing genetic and phenotypic data associated with rare CFTR variants.

Most of the 2,000 variants identified in the CFTR (cystic fibrosis transmembrane regulator) gene are rare or private. Their interpretation is hampered by the lack of available data and resources, making patient care and genetic counseling challenging. We developed a patient-based database dedicated to the annotations of rare CFTR variants in the context of their cis- and trans-allelic combinations. Based on almost 30 years of experience of CFTR testing, CFTR-France (https://cftr.iurc.montp.inserm.fr/cftr) currently compiles 16,819 variant records from 4,615 individuals with cystic fibrosis (CF) or CFTR-RD (related disorders), fetuses with ultrasound bowel anomalies, newborns awaiting clinical diagnosis, and asymptomatic compound heterozygotes. For each of the 736 different variants reported in the database, patient characteristics and genetic information (other variations in cis or in trans) have been thoroughly checked by a dedicated curator. Combining updated clinical, epidemiological, in silico, or in vitro functional data helps to the interpretation of unclassified and the reassessment of misclassified variants. This comprehensive CFTR database is now an invaluable tool for diagnostic laboratories gathering information on rare variants, especially in the context of genetic counseling, prenatal and preimplantation genetic diagnosis. CFTR-France is thus highly complementary to the international database CFTR2 focused so far on the most common CF-causing alleles.

Highlighting the impact of cascade carrier testing in cystic fibrosis families.

BACKGROUND: Cascade carrier testing within cystic fibrosis (CF) affected families offers relatives of CF patients the opportunity to know their status regarding the mutation that segregates within their family, and thus to make informed reproductive choices. As an Australian study has recently shown that this test seemed underused, we searched to assess uptake of this test in a European area where CF is common, and to report its public health implications. METHODS: This study relied on 40 CF-affected families from western Brittany, France. Investigations included drawing of family trees and registration of carrier tests performed in those families. RESULTS: Of the 459 relatives eligible for testing, 185 were tested, leading to an adjusted uptake rate of testing of 40.7% (95% CI: [34.1%; 47.3%]). The main predictors for having testing were being female (p=0.031) and having a high prior risk (p<0.001). Planning a pregnancy or expecting a child (reported in at least 38.4% of tested relatives) also appeared critical in choosing to be tested. Overall, carrier testing allowed to reassure more than 1/4 of the relatives and to detect five new 1-in-4 at-risk couples who then requested prenatal diagnosis. CONCLUSIONS: This observational study assesses, for first time in Europe, uptake of CF cascade carrier testing within CF families, which is a critical tool to reassure non-carriers and to detect early new at-risk couples.

Cascade testing in families of carriers identified through newborn screening in Western Brittany (France).

BACKGROUND: Newborn screening (NBS) for cystic fibrosis (CF) can lead to the detection of healthy carriers. We report a unique assessment of family testing following the identification of carriers by NBS for over 20 years, in an area where CF is frequent. METHODS: We reviewed all of the carriers identified by NBS between 1991 and 2010 and registered the tests done in those families. RESULTS: NBS identified 0.1% of the newborns as carriers, which correspond only to 2.6% of the expected carriers born within the period, and 1/3 of those with an increased IRT level. Of the 195 families, 75.9% requested testing (2.5 tests per family). We identified 183 carriers and five 1-in-4 risk couples. Reassurance about genetic status was provided to 96% of the couples. CONCLUSIONS: Carriers detected by NBS appeared to be well managed in our area, and cascade testing that informs on genetic status seems relatively active.

Relationship of non-visualization of the fetal gallbladder and amniotic fluid digestive enzymes analysis to outcome.

OBJECTIVE: The aims of this study were evaluate the significance of non-visualization of fetal gallbladder at routine ultrasound scan in a series of 102 cases and to determine the contribution of amniotic fluid digestive enzyme (AF-DE) analysis towards the outcome. METHOD: This is a multicenter retrospective study. Outcome of pregnancies, karyotype, and result of screening for CFTR gene mutations were known in all cases. Amniotic fluid gamma-glutamyl-transpeptidase and intestinal alkaline phosphatase isoenzyme were assayed. RESULTS: Non-visualization of the fetal gallbladder was associated with a severe disease in 25 cases (cystic fibrosis in ten, biliary duct atresia in eight, digestive tract anomalies in six, and chromosomal anomaly in one). In the remaining 77 cases, gallbladder agenesis was diagnosed in 22, and in 55, the gallbladder was subsequently demonstrated. Before 22 weeks of gestation (n=30), an abnormal AF-DE pattern had a 90% sensitivity and 80% specificity in detecting cystic fibrosis or biliary duct atresia. After 22 weeks, sensitivity fell to 53%. The AF-DE pattern was normal in 82% of gallbladder agenesis cases (benign) and in 91% of the cases where the gallbladder was subsequently detected. CONCLUSION: Non-visualization of the fetal gallbladder was associated with severe anomalies in 24% of cases. Prior to 22 weeks, determination of AF-DE contributes to the prediction of biliary atresia or the presence of cystic fibrosis.

Evidence for decline in the incidence of cystic fibrosis: a 35-year observational study in Brittany, France.

BACKGROUND: Cystic fibrosis (CF) is an autosomal recessive disorder whose incidence has long been estimated as 1/2500 live births in Caucasians. Expanding implementation of newborn screening (NBS) programs now allows a better monitoring of the disease incidence, what is essential to make reliable predictions for disease management. This study assessed time trends in the birth incidence of CF over a long period (35 years: 1975-2009) in an area where CF is frequent (Brittany, France) and where NBS has been implemented for more than 20 years. METHODS: This study enrolled CF patients born in Brittany between January 1st 1975 and December 31st 2009 (n = 483). Time trends in incidence were examined using Poisson regression and mainly expressed using the average percent change (APC). RESULTS: The average number of patients born each year declined from 18.6 in the late 1970's (period 1975-79) to 11.6 nowadays (period 2005-09). The corresponding incidence rates dropped from 1/1983 to 1/3268, which represented a decline close to 40% between these two periods (APC = -39.3%, 95% CI = -55.8% to -16.7%, p = 0.0020). A clear breakpoint in incidence rate was observed at the end of the 1980's (p < 0.0001). However, the incidence rate has remained quite stable since that time (annual APC = -1.0%, 95% CI = -3.0% to 1.1%, p = 0.3516). CONCLUSIONS: This study provides an accurate picture of the evolution of the incidence of a genetic disease over a long period and highlights how it is influenced by the health policies implemented. We observed a 40% drop in incidence in our area which seems consecutive to the availability of prenatal diagnosis.

Nonvisualization of fetal gallbladder increases the risk of cystic fibrosis.

OBJECTIVE: The aim of our study is to evaluate the prevalence of cystic fibrosis (CF) in fetuses referred for genetic testing because of ultrasonographic sign (nonvisualized fetal gallbladder--NVFGB). METHOD: We reviewed the results of CFTR gene analysis over the period 2002 to 2009 in all consecutive cases referred because of NVFGB in Western France. We correlated these data with the presence of a more classical ultrasonographic finding (fetal echogenic bowel - FEB). RESULTS: Cystic fibrosis was diagnosed in 5 of the 37 fetuses with NVFGB (13.5%, 95% confidence interval (CI): [2.5%; 24.5%]) and in only 9 of the 229 other cases referred because of FEB (3.9%, 95% CI: [3.2%; 14.7%]). In our series, all CF-affected fetuses with NVFGB also had FEB. The risk of CF was 11.6-fold higher in fetuses with both indications (NVFGB + FEB) than in fetuses with isolated FEB (45.5% vs 3.9%, RR = 11.6, 95% CI: [4.7%; 28.8%], p = 0.0001). We also estimated that the residual risk of CF was less than 1 in 68 (1.5%) when a single mutation was identified in the fetus by our molecular protocol. CONCLUSION: Ultrasonographic evidence of NVFGB is an additional risk factor for CF in cases with FEB.

Focus on cystic fibrosis and other disorders evidenced in fetuses with sonographic finding of echogenic bowel: 16-year report from Brittany, France.

OBJECTIVE: Pregnancies medical follow-up and ultrasonography development have enabled detection of fetal echogenic bowel, a sign associated with various pathologies, including cystic fibrosis. Based on the long experience of a region where cystic fibrosis is frequent (Brittany, France), we describe disorders diagnosed in fetal echogenic bowel fetuses and assess ultrasonography ability in detecting cystic fibrosis in utero. STUDY DESIGN: We reviewed the cases of fetal echogenic bowel diagnosed in pregnant women living in Brittany and referred for CFTR gene analysis over the 1992-2007 period (n = 289). RESULTS: A disorder was diagnosed in 32.2% of the fetuses, cystic fibrosis being the most commonly identified (7.6%). We also found digestive malformations (7.0%), chromosomal abnormalities (3.7%), and maternofetal infections (3.7%). Combining these data with our ongoing newborn screening program since 1989 showed that ultrasonography enabled diagnosis of 10.7% of the cystic fibrosis cases. CONCLUSION: This study highlights the importance of pregnancy ultrasound examinations and their efficiency in detecting cystic fibrosis.

Pulmonary outcome differences in U.S. and French cystic fibrosis cohorts diagnosed through newborn screening.

BACKGROUND: A comparison of the longitudinal progression of lung disease in cystic fibrosis patients identified through newborn screening (NBS) in cohorts located in two different countries has never been performed and was the primary objective of this study. METHODS: The study included 56 patients in Brittany diagnosed through NBS between 1989 and 1994 and 69 similar patients in Wisconsin between 1985 and 1994. The onset and progression of lung disease was radiographically quantified using the Wisconsin Chest X-ray (WCXR) scoring system. A single pediatric pulmonologist blinded to all identifiers scored the films. RESULTS: Generalized estimating equation analyses adjusted for age, genotype, sex, pancreatic insufficiency, and meconium ileus showed worse WCXR scores in Brittany patients compared to Wisconsin patients (average score difference=4.48; p<0.001). Percent predicted FEV1 was also worse among Brittany patients (p<0.001). CONCLUSIONS: The finding of milder radiographically-quantified lung disease using the WCXR scoring system, as well as better FEV1 values, may be explained by variations in nutrition, environmental exposures, or healthcare delivery.

Clinical changes of patients with cystic fibrosis during transition from pediatric to adult care.

PURPOSE: To evaluate the clinical changes of adults with cystic fibrosis (CF) during transition from a pediatric to adult CF center. METHODS: Data were collected at the time of transfer, 1 year earlier and 1 year later, for all patients in our adult CF center arriving from one of the three pediatric CF centers in Paris between January 2001 and June 2004. RESULTS: Sixty-three of the 68 patients (transferred at a median age of 21.0 years) were regularly attending this adult CF center after 1 year and one had died. The mean number of outpatient visits increased in the year after transfer (5.7 vs. 3.8 in the year before, p < .001). The occurrence of clinical events and the rate of bronchial colonization did not change. Pseudomonas aeruginosa was found in about 60% of patients at any time. Pulmonary function declined regularly with no statistically significant difference in the rate of decline between the 2 years of follow-up (FEV 1 was 54.7% predicted at transfer). Nutritional status remained stable (mean body mass index was 19.1 kg/m2). The number and duration of oral and i.v. antibiotic courses did not change, but more patients received them at home (p < .001) and self-administered physiotherapy after transfer (p = .001). The proportion of students decreased from 79.3% to 48.1% (p = .02) and the proportion in the workforce increased from 12.7% to 20.4% after transfer. CONCLUSIONS: Patients with CF remained clinically stable during transition and progressively acquired autonomy.

Prenatal diagnosis of cystic fibrosis: the 18-year experience of Brittany (western France).

OBJECTIVE: This study reports 18 years of experience in prenatal diagnosis (PD) of cystic fibrosis (CF) in a region where CF is frequent and the uptake of PD is common (Brittany, western France). METHOD: All PDs made over the period 1989-2006 in women living in Brittany were collected. RESULTS: We recorded 268 PDs made in 1 in 4 risk couples, plus 22 PDs directly made following the sonographic finding of echogenic bowel. Most of the 268 PDs were done in couples already having CF child(ren) (n = 195, 72.8%). Close to one-fifth followed cascade screening (n = 49, 18.3%), which identified 26 new 1 in 4 risk couples among the relatives of CF patients or of carriers identified through newborn screening (NBS). The remaining PDs were mainly made in couples whose 1 in 4 risk was evidenced following the diagnosis of echogenic bowel in a previous pregnancy (n = 22, 8.2%). Although patients' life expectancy has considerably improved, in our population the great majority of couples chose pregnancy termination when PD indicated that the foetus had CF (95.9%). CONCLUSION: This study describes the distribution of PDs according to the context in which the 1 in 4 risk was discovered and highlights the real decisions of couples as regards pregnancy termination after a positive PD.

Time trends in birth incidence of cystic fibrosis in two European areas: data from newborn screening programs.

OBJECTIVE: To determine the incidence of cystic fibrosis (CF) and its time trends over a 16-year period (1990 to 2005) in 2 European regions with a long history of newborn screening (NBS) for CF, and to investigate the impact of some external factors. STUDY DESIGN: This study focused on data from NBS and prenatal diagnosis (PD) in Brittany (western France) and Veneto/Trentino Alto-Adige (northeastern Italy). RESULTS: Similar birth incidences of CF were observed in the 2 regions (1/3153 vs 1/3540; P = .245). Time trend analysis using Poisson regression revealed that the birth incidence decreased significantly in the Italian area only (average annual percent change [AAPC] = -4.7%; 95% confidence interval [CI] = -7.3 to -2; P = .0008). The use of PD appeared more common in Brittany, and considering the terminations of CF-affected fetuses, the adjusted incidence was 1/2191 in Brittany and 1/3116 in Veneto/Trentino, corresponding to variations of 30.5% (highly significant; P = .0002) and 12% (not significant; P = .16), respectively. Recording the reason for each PD allowed ready assessment of the affect of various public health policies on incidence. The affect of population mixing also appeared to be relevant in the Italian area. CONCLUSIONS: This study highlights how the incidence of CF has evolved in 2 European regions that have different attitudes toward PD and immigration policy.

Paternity in men with cystic fibrosis: a retrospective survey in France.

BACKGROUND: Because more patients reach adulthood, new questions as "what about having a child and/or paternity responsibility?" arose. METHOD: We performed a retrospective investigation based on the French CF registry. The context of the paternity and the health status of fathers were recorded. A comparison with clinical status of non-father patients and a compilation of follow-up data to evaluate its impact were done. RESULTS: Forty-eight men had 69 children. One fourth was said to be natural conceptions, 69% needed assisted reproduction techniques. No child had CF. Clinical status of men was satisfactory: mean BMI was 20.9 kg/m(2) and mean FEV(1) and FVC were 50.5% and 69.2% of predicted, respectively. When matched to CF non-fathers, few significant differences appeared. More non-fathers were F508del/F508del (p=0.03). Fathers' sputum cultures were positive for non-Pseudomonas aeruginosa strain (p=0.05), including Staphylococcus aureus (p=0.01). Mean age at diagnosis was higher, and based on minor evidence of sterility as first symptom leading to the diagnosis of CF (p=0.01) or aspergillosis (p=0.03). The 3-year follow-up showed no degradation of the clinical status. CONCLUSION: Men having paternity responsibility over children did not differ from the CF male population and neither did it seem to have an impact on the disease course.

Misprocessing of the CFTR protein leads to mild cystic fibrosis phenotype.

Cystic fibrosis (CF) is mainly caused by mutations that interfere with the biosynthetic folding of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. The aim of this study was to determine the mechanism of dysfunction of a disease-causing mutation associated with variable phenotypes. In order to attain these objectives, we studied the effect of the p.L206W mutation on CFTR protein production and function, and we examined the genotype-phenotype correlation of [p.L206W]+[p.F508del] patients. We showed that p.L206W is a processing (class II) mutation since the CFTR biosynthetic pathway was severely impaired, whereas single-channel measurements indicated ion conductance similar to the wild-type protein. These data raise the larger question of the phenotypic variability of class II mutants, including p.F508del. Since multiple potential partners could modify the processing of the CFTR protein during its course to the cell surface, environmental and other genetic factors might contribute to this variability.

Cystic fibrosis at the Reunion Island (France): spectrum of mutations and genotype-phenotype for the Y122X mutation.

BACKGROUND: The Reunion Island is a French administrative department located in the Indian Ocean between the islands of Madagascar and Mauritius. Its population is known to be at a high risk of cystic fibrosis (CF). METHODS: Data concerning all CF patients born at the Reunion Island was extracted from the French CF Registry. Twenty-eight DeltaF508/DeltaF508, 17 Y122X/DeltaF508, and 11 Y122X/Y122X were included in a genotype-phenotype study. RESULTS: The detection rate of the CFTR mutations was 83% among the CF patients born at the Reunion Island. Three CFTR mutations accounted for 75% of the detected CF alleles at the Reunion Island (DeltaF508, Y122X, and 3120 + 1G-->A.). The DeltaF508/DeltaF508, DeltaF508/Y122X, and Y122X/Y122X genotypes accounted for 60.2% of the CF patients. Patients carrying at least one Y122X mutation were pancreatic insufficient, had high sweat chloride values and significantly lower anthropometric measures. The mean anthropometric values in all three groups were lower that in the whole CF population followed in "continental" France. This may reflect the poor compliance and even the refusal of treatment noted by the clinicians. CONCLUSIONS: The distribution of CFTR mutations could be explained by the history of the Reunion Island: admixture of French settlers, African and Asian populations, founder effect and isolation followed by genetic drift. The Y122X allele appears to be associated with a severe phenotype.

Genotype-phenotype relationship for five CFTR mutations frequently identified in western France.

BACKGROUND: Cystic fibrosis (CF) is the most common inherited disorder in Caucasian populations, with more than 1000 cystic fibrosis transmembrane conductance regulator (CFTR) mutations presently described. The distribution of the mutations ranges widely between countries and/or ethnic groups. Multicentric studies are usually needed to study the genotype-phenotype correlations. METHODS: Since 1992, the French CF Registry (FCFR) has collected and analyzed data from most of the CF patients regularly seen in CF care centres in France. We compared the mutation distribution of the patients born in western France to that of those born elsewhere in France. Then we extracted the available data for all the compound heterozygotes carrying the DeltaF508 allele and one of the following mutations: DeltaI507, 1078delT, 4005+1G->A, E60X and W846X, and matched a patient homozygous for the DeltaF508 mutation for each of them. RESULTS: Western France appeared to have a specific distribution of some CF mutations. Furthermore, disparities were found regarding the mutation repartition (DeltaI507 in Normandy, 1078delT, 4005+1G->A and W846X in western Brittany). Genotype-phenotype correlations showed a wide heterogeneity. Although variations were found, DeltaI507/DeltaF508, 4005+1G->A/DeltaF508 and 1078delT/DeltaF508 patients appeared to have a similar disease as the DeltaF508/DeltaF508 patients. Although the W846X and E60X mutations should be considered as severe alleles as regards to pancreatic function, they were associated with less severe pulmonary manifestations and, probably, better prognosis. CONCLUSION: The knowledge of the distribution of uncommon CF mutations specific to particular areas and of their associated phenotype makes up an essential tool in the management of local CF patients.

Spatial and temporal distribution of cystic fibrosis and of its mutations in Brittany, France: a retrospective study from 1960.

Cystic fibrosis (CF) is the most common severe inherited disorder that affects children in Caucasian populations. The aim of this study was to define the spatial and temporal distribution of CF and its mutations in Brittany (western France) where the frequency of the disease is high. We retrospectively registered all CF patients born in Brittany since 1960 by cross-checking various data sources (e.g. medical care centres, genetics laboratories, hospital archives). Councils were contacted so that the place of residence of patients at birth could be determined. Moreover, the spectrum of CF transmembrane conductance regulator (CFTR) mutations and their spatial distribution across Brittany were determined. A total of 520 patients was registered in this study. The incidence of CF was assessed according to administrative (department, district) and diocesan divisions of Brittany and its evolution analysed over four decades. The incidence of CF was 1/2630, with a west/east gradient that was confirmed over time (Finistère: 1/2071 vs Ille-et-Vilaine: 1/3286). At present, the incidence of CF is decreasing, mainly as a result of prenatal diagnosis. An excellent mutation detection rate of 99.7% was obtained. Western Brittany presented a specific spectrum of mutations: 1078delT (9.4% of mutated alleles in the diocese of Cornouaille), G551D (7.7% in the diocese of Léon), 4005+1G-->A (2.9% in Cornouaille) and W846X (1.5% in western Brittany). On the other hand, the eastern region showed a spectrum more similar to the overall picture in France as a whole. This study enabled a precise measurement of the incidence of CF in Brittany to be obtained. The high frequency of the CFTR mutated alleles may result from founder effects and genetic drifts. Moreover, the study brings together the regional specificities of the CFTR gene and highlights disparities that exist in this part of France, both in incidence and in mutation distribution. These are attributable to different degrees of isolation and of population movements between the eastern and western parts of the region. Given that this is the first time that such a detailed study of the CFTR gene has been performed on a large population, this heightened knowledge of the epidemiology of CF in Brittany should provide a basis for the improvement of diagnostic strategies and refinement of genetic counselling.