Frequency of cystic fibrosis transmembrane conductance regulator gene mutations and 5T allele in patients with allergic bronchopulmonary aspergillosis.

Service de Pneumologie, Cliniques Universitaires de Mont-Godinne, Université Catholique de Louvain, Yvoir, Belgium. eric.marchand@pneu.ucl.ac.be

STUDY OBJECTIVE: To assess the frequency of cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations in patients with allergic bronchopulmonary aspergillosis (ABPA). DESIGN: Case-control study. All subjects in the study were screened for the presence of 13 mutations in the CFTR gene (R117H, 621 + 1G(-)>T, R334 W, Delta F508, Delta I507, 1717-1G(-)>A, G542X, R553X, G551D, R1162X, 3849 + 10kbC(-)>T, W1282X, and N1303K). Moreover, they were also screened for the presence of the 5T variant in intron 8. SETTING: University hospital and community-based hospital. PATIENTS: Twenty-one white patients with ABPA participated in the study. The presence of CFTR mutations was also investigated in 43 white subjects with allergic asthma who did not show sensitization to Aspergillus fumigatus and in 142 subjects seeking genetic counseling for diseases other than cystic fibrosis (CF). RESULTS: Six patients with ABPA were found to be heterozygous for one CFTR mutation, including Delta F508 (n = 2), G542X (n = 1), R1162X (n = 1), 1717-1G(-)>A (n = 1), and R117H (n = 1). The 5T allele was not detected in ABPA patients. None of the ABPA patients showed sweat chloride concentrations > 60 mEq/L. The frequency of CFTR mutation carriers was significantly higher in ABPA patients (6 of 21 patients; 28.5%) than in control asthmatic subjects (2 of 43 subjects; 4.6%; p = 0.01) and in subjects seeking genetic counseling (6 of 142 subjects; p < 0.001). CONCLUSION: These findings indicate that in patients without a clinical diagnosis of CF, CFTR gene mutations could be involved in the development of ABPA, in association with other genetic or environmental factors.

PMID: 11243954 [PubMed - indexed for MEDLINE]

Genetic risk factors in infertile men with severe oligozoospermia and azoospermia.

Andrology Unit, Department of Urology, Erasmus University Medical Centre, Rotterdam, The Netherlands. Dohle@urol.azr.nl

BACKGROUND: Male infertility due to severe oligozoospermia and azoospermia has been associated with a number of genetic risk factors. METHODS: In this study 150 men from couples requesting ICSI were investigated for genetic abnormalities, such as constitutive chromosome abnormalities, microdeletions of the Y chromosome (AZF region) and mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. RESULTS: Genetic analysis identified 16/150 (10.6%) abnormal karyotypes, 8/150 (5.3%) AZFc deletions and 14/150 (9.3%) CFTR gene mutations. An abnormal karyotype was found both in men with oligozoospermia and azoospermia: 9 men had a sex-chromosomal aneuploidy, 6 translocations were identified and one marker chromosome was found. Y chromosomal microdeletions were mainly associated with male infertility, due to testicular insufficiency. All deletions identified comprised the AZFc region, containing the Deleted in Azoospermia (DAZ) gene. CFTR gene mutations were commonly seen in men with congenital absence of the vas deferens, but also in 16% of men with azoospermia without any apparent abnormality of the vas deferens. CONCLUSIONS: A genetic abnormality was identified in 36/150 (24%) men with extreme oligozoospermia and azoospermia. Application of ICSI in these couples can result in offspring with an enhanced risk of unbalanced chromosome complement, male infertility due to the transmission of a Y-chromosomal microdeletion, and cystic fibrosis if both partners are CFTR gene mutation carriers. Genetic testing and counselling is clearly indicated for these couples before ICSI is considered.

PMID: 11756355 [PubMed - indexed for MEDLINE]

Cystic Fibrosis testing among Arab-Americans.

Medical Genetics, Henry Ford Hospital, Detroit, MI 48202, USA.

PURPOSE: Limited data regarding the cystic fibrosis carrier frequency and mutation detection rate is available for Arab-Americans. We retrospectively determined the frequency of carriers among Arab-Americans undergoing preconception and prenatal carrier screening in our laboratories. METHODS: Between October, 2001 and June, 2005, we performed carrier screening on 805 Arab-Americans, testing for at least the original 25 mutations recommended by the American College of Medical Genetics. We compared our results to previously published studies among Arabic cystic fibrosis patients. We also performed diagnostic testing on seven individuals. RESULTS: Seven carriers were identified, with an observed carrier frequency of 1 in 115. The most common mutation we identified was W1282X (57% of the mutations detected), followed by DeltaF508 and R117H. Three of 7 patients with a known or suspected diagnosis had two identifiable mutations, including 1548delG, DeltaF508, W1282X, 2789 + 5G>A and R170H. CONCLUSION: The current recommended carrier screening panel includes only six mutations reported among Arabic cystic fibrosis patients, accounting for 37.1% of the mutations identified among this group. The addition of 1548delG, I1234V, H139L and 4010del4 as part of an extended screening panel would increase the detection rate to 66.3%, similar to the mutation detection rates in other races/ethnic groups.

PMID: 16617247 [PubMed - indexed for MEDLINE]

CFTR 5T variant has a low penetrance in females that is partially attributable to its haplotype.

Department of Molecular Genetics, Quest Diagnostics Nichols Institute, San Juan Capistrano, California 92690, USA.

PURPOSE: The study's purpose was to understand the molecular basis for different clinical phenotypes of the 5T variant, a tract of 5 thymidines in intron 8 of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which disrupts processing of CFTR mRNA and reduces synthesis from the corresponding CFTR alleles. METHOD: We analyzed the polymorphic TG dinucleotide repeat adjacent to the 5T variant in intron 8 and the codon 470 in exon 10. Patients selected for this study were positive for both the 5T variant and the major cystic fibrosis mutation, Delta F508. Almost all Delta F508 mutation alleles occur in a 10TG-9T-470M haplotype. Therefore, it is possible to determine the haplotype of the 5T variant in trans. RESULTS: Of the 74 samples analyzed, 41 (55%) were 11TG-5T-470M, 31 (42%) were 12TG-5T-470V, and 2 (3%) were 13TG-5T-470M. Of the 49 cases for which we had clinical information, 17.6% of females (6/34) and 66.7% of males (10/15) showed symptoms resembling atypical cystic fibrosis. The haplotype with the highest penetrance in females (42% or 5/12) and more than 80% (5/6) in males is 12TG-5T-470V. We also evaluated 12 males affected with congenital bilateral absence of vas deferens and positive for the 5T variant; 10 of 12 had the 12TG-5T-470V haplotype. CONCLUSION: Overall, the 5T variant has a milder clinical consequence than previously estimated in females. The clinical presentations of the 5T variant are associated with the 5T-12TG-470M haplotype.

PMID: 16778595 [PubMed - indexed for MEDLINE]

Population screening for cystic fibrosis: knowledge and emotional consequences 18 months later.

Center for Child Health Research, The University of Western Australia, Telethon Institute for Child Health Research, West Perth, Western Australia.

We assessed cystic fibrosis (CF) knowledge and emotional consequences of CF population testing 18 months after screening was offered. Questionnaires were sent to 593 individuals and 353 responded (59.5%). All respondents had sound knowledge of CF disease, although carriers were more likely to correctly state the pattern of CF inheritance and CF carrier rate in Australia. Eleven of 47 carriers falsely believed they were only very likely to be carriers, while nearly a third of test-negative individuals falsely believed they were definitely not carriers. Imprecise recall of the meaning of results may be due to memory loss over time, simplification of result meaning and minimization of risk. The Health Orientation Scale (HOS) was used to assess emotional consequences of CF carrier testing 18 months after testing. Both carriers and test-negative individuals thought most carriers would experience more negative feelings than most non-carriers. Carriers experienced less positive feelings about their test result compared to non-carriers. Interestingly, the carriers' own feelings about their result were more positive compared to how they thought most carriers would feel. These results suggest that carriers experience minimal adverse psychological effects, although a negative social stigma may be attached to carrying the CF gene mutation. Copyright 2003 Wiley-Liss, Inc.

PMID: 12833400 [PubMed - indexed for MEDLINE]

Complete and rapid scanning of the cystic fibrosis transmembrane conductance regulator (CFTR) gene by denaturing high-performance liquid chromatography (D-HPLC): major implications for genetic counselling.

EFS-Bretagne, CHU, Brest, France.

More than 900 mutations and more than 200 different polymorphisms have now been reported in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Ten years after the cloning of the CFTR gene, the complete scanning of the 27 exons to identify known and novel mutations remains challenging. Rapid accurate identification of mutated alleles is important for prenatal diagnosis, for cascade screening in families at risk of cystic fibrosis (CF) and for understanding the correlation between genotype and phenotype. In this study, we report the successful use of denaturing ion-pair reverse-phase high performance liquid chromatography (D-HPLC) to analyse rapidly the complete coding sequence of the CFTR gene. With 27 pairs of polymerase chain reaction primers, we optimised the temperature conditions required for the analysis of each amplicon and validated thetest conditions on samples from a panel of 1552 CF patients who came from France and other European countries and who had mutations and polymorphisms located in the various melting domains of the gene. D-HPLC identified 415 mutated alleles previously characterised by denaturing gradient gel electrophoresis and DNA sequencing, plus 74 novel mutations reported here.This new technique for screening DNA for sequence variation was extremely accurate (it identified 100% of the CFTR alleles tested so far) and rapid (the complete CFTR gene could be analysed in less than a week). Our approach should reduce the number of untyped CF alleles in populations and thus decrease the residual risk in couples at risk of CF. This technique may be important not only for CF,but also for many other genes with a high frequency of point mutations at a variety of sites.

PMID: 11379874 [PubMed - indexed for MEDLINE]

Genetic counseling after implementation of statewide cystic fibrosis newborn screening: Two years' experience in one medical center.

Division of Genetics, Tufts University School of Medicine, Floating Hospital for Children at New England Medical Center, Boston, Massachusetts 02111, USA.

PURPOSE: To study the follow-up of genetic counseling performed in families with a newborn detected with one cystic fibrosis (CF) mutation in a statewide newborn screening pilot program. METHODS: Newborns in Massachusetts with an elevated trypsinogen level on newborn screen who are found to have one mutation for CF on a selected mutation assay undergo sweat testing for CF, and their families receive genetic counseling. The genetic counseling focuses on carrier risk for the parents of the newborn and offers carrier testing. We studied the yield of genetic counseling and the resulting genetic testing performed on the families of infants found to be CF carriers who underwent sweat testing in a single institution. RESULTS: Of 102 newborns evaluated with a single CF mutation, 2 (twins) had sweat test results consistent with CF. A total of 101 families were counseled, and 95 were offered DNA-based CF carrier testing. Eighty-two percent of all parents chose to have CF carrier testing, and in five couples, both members were carriers. One of these couples (whose newborn was only a carrier) had an older child who was unexpectedly found to have CF. CONCLUSIONS: Sweat testing of newborns at increased risk for CF in conjunction with genetic counseling for their parents allows identification of infants with CF, finds couples at high risk for having a child with CF, identifies previously undiagnosed siblings with CF, and allows for potential identification of CF carriers in the extended family.

PMID: 11715005 [PubMed - indexed for MEDLINE]

Detection of cystic fibrosis transmembrane conductance regulator (CFTR) gene rearrangements enriches the mutation spectrum in congenital bilateral absence of the vas deferens and impacts on genetic counselling.

Service de Biochimie et Génétique Moléculaire, AP-HP et INSERM U841, IMRB, eq 21, Hôpital Henri-Mondor, Créteil, France.

BACKGROUND: Mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene have been widely detected in infertile men with congenital bilateral absence of the vas deferens (CBAVD). Despite extensive analysis of the CFTR gene using varied screening methods, a number of cases remain unsolved and could be attributable to the presence of large gene rearrangements, as recently shown for CF patients. METHODS: We carried out a complete CFTR gene study in a group of 222 CBAVD patients with strict diagnosis criteria and without renal anomaly, and searched for rearrangements using a semi-quantitative assay in a subgroup of 61 patients. RESULTS: The overall mutation detection rate was 87.8%, and 82% of patients carried two mutations. Ten out of the 99 different mutations accounted for 74.6% of identified alleles. Four large rearrangements were found in patients who already carried a mild mutation: two known partial deletions (exons 17a to 18 and 22 to 23), a complete deletion and a new partial duplication (exons 11 to 13). The rearrangements accounted for 7% of the previously unknown alleles and 1% of all identified alleles. CONCLUSIONS: Screening for rearrangements should be part of comprehensive CFTR gene studies in CBAVD patients and may have impacts on genetic counselling for the patients and their families.

PMID: 17329263 [PubMed - indexed for MEDLINE]

XV-2c/KM19 haplotypes analysis of cystic fibrosis patients from western Mexico.

División de Medicina Molecular, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jalisco, México.

The analysis of polymorphic markers within or closely linked to the cystic fibrosis transmembrane regulator (CFTR) gene is useful as a molecular tool for carrier detection of known and unknown mutations. To establish the association between mutations in the CFTR gene in western Mexican cystic fibrosis (CF) patients, the distribution of XV2c/KM19 haplotypes was analyzed by PCR and restriction enzyme digestion in 384 chromosomes from 74 CF patients, their unaffected parents, and normal subjects. The haplotype analysis revealed that haplotype B was present in 71.9% of CF chromosomes compared to 0% of non-CF chromosomes. The F508del and G542X mutations were strongly associated with haplotype B (96.7% and 100% of chromosomes, respectively). The haplotype distribution of the CF chromosomes carrying other CFTR mutations had a more heterogeneous background. Our results show that haplotype B is associated with CFTR mutations. Therefore, haplotype analysis is a suitable alternate strategy for screening CF patients with a heterogeneous clinical picture from populations with a high molecular heterogeneity where carrier detection programs are not available. In addition, it may be a helpful diagnostic tool for genetic counseling and carrier detection in the relatives of CF patients and in couples who are planning to have children.

PMID: 18788470 [PubMed - indexed for MEDLINE]

Molecular analysis of mutations and polymorphisms in the CFTR gene in male infertility.

Unità di Medicina della Riproduzione - Fondazione HERA, Viale Marco Polo 39/A, 95126 Catania, Italy.

Mutations of the cystic fibrosis transmembrane regulator (CFTR) gene and polymorphisms, such as the (TG)m and Tn polymorphic loci in intron 8 at the splice acceptor site of exon 9, can cause male infertility. The aim of this study was to investigate the frequency of the most prevalent cystic-fibrosis-causing mutations, the IVS8-Tn alleles and IVS8-TG12 variant in the presence of IVS8-5T in patients with altered semen parameters (group I with obstructive azoospermia, group II with secretory azoospermia and group III with severe oligozoospermia) compared with a control group with normozoospermia. CFTR mutations were found in 26.5% and 14.3% of chromosomes of patients of group I and II respectively (P < 0.001, P < 0.05). The frequency of the 5T allele was 23.5% in patients in group I (P < 0.01), and was linked exclusively with TG12 allele. The present study reports for the first time a high proportion of the 5T allele in patients in group III (9.2%, P < 0.05). These results underline the importance of performing molecular analysis of mutations and IVS8-Tn polymorphism in the CFTR gene and appropriate genetic counselling to all couples undergoing assisted reproductive technologies when the partner has azoospermia or severe oligozoospermia.

PMID: 18616886 [PubMed - indexed for MEDLINE]

Erratum in:

Hum Mutat. 2005 Feb;25(2):223.

Identification of novel and rare mutations in California Hispanic and African American cystic fibrosis patients.

Institute for Molecular and Human Genetics, Georgetown University Medical Center, Washington, DC 20007-2113, USA.

In ethnic heterogeneous California, complete genetic information is currently lacking to build solid population-based cystic fibrosis (CF) screening programs because a large proportion of mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR/ABCC7) are still unknown, especially in non-Caucasian patients. A total of 402 [46 African American+356 Hispanic] Hispanic and African American patients from California CF patient registry were included in this study. Patients with at least one unidentified mutant allele were asked to donate blood samples for further analysis, first by Genzyme Genetics for a panel of 87 known mutations, followed by temporal temperature gradient gel electrophoresis (TTGE) scanning of the entire coding exons of CFTR gene. A total of eight novel mutations; one missense mutation, one splice-site mutation and six frame-shift mutations were identified. In addition to the eight novel mutations, 20 [corrected] distinct rare mutations that are not in the current available commercial mutation panels were identified by TTGE. The overall detection rate was raised to 95.7% for African American and 94.5% for Hispanic. The discovery of recurrent rare and novel mutations improves the diagnosis and care of persons with CF and improves our ability to adequately and equitably provide screening and genetic counseling services to non-Caucasians. Copyright 2004 Wiley-Liss, Inc.

PMID: 15365999 [PubMed - indexed for MEDLINE]

[Cystic fibrosis transmembrane conductance regulator (CFTR) gene: mutations and clinical phenotypes]

Klinisk Genetisk Afdeling, H:S Rigshospitalet, DK-2100 København ø.

Cystic fibrosis (CF) is caused by mutation in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. CF is characterised by chronic lung infections, pancreas insufficiency and, in males, congenital bilateral absence of the vas deferens (CBAVD). Furthermore, mutations in the CFTR are associated with several isolated, CF-related symptoms such as chronic lung diseases, CBAVD idiopathic pancreatitis and asthma. These patients have a higher frequency of CFTR mutations than unaffected individuals. The mutations found are not typical for the CF patients and are classified as mild mutations. One of these mutations (IVS8-5T) is frequently found in patients with the CF-related diseases, and in particular in patients with CBAVD. When a CFTR mutation is identified, genetic counselling and a mutation analysis should be offered to the relevant family members.

PMID: 12661515 [PubMed - indexed for MEDLINE]

Novel CFTR missense mutations in Brazilian patients with congenital absence of vas deferens: counseling issues.

Department of Pediatrics, São Paulo University, Medical College, São Paulo, Brazil. patricp@icr.hcnet.usp.br

PURPOSE: Screening for mutations in the entire Cystic Fibrosis gene (CFTR) of Brazilian infertile men with congenital absence of vas deferens, in order to prevent transmission of CFTR mutations to offspring with the use of assisted reproductive technologies. METHOD: Specific polymerase chain reaction (PCR) primers were designed to each of the 27 exons and splicing sites of interest followed by single strand conformational polymorphism and Heteroduplex Analysis (SSCP-HA) in precast 12.5% polyacrylamide gels at 7 masculineC and 20 masculineC. Fragments with abnormal SSCP migration pattern were sequenced. RESULTS: Two novel missense mutations (S753R and G149W) were found in three patients (two brothers) together with the IVS8-5T allele in hetrozygosis. CONCLUSION: The available screenings for CF mutations do not include the atypical mutations associated to absence of vas deferens and thus, when these tests fail to find mutations, there is still a genetic risk of affected children with the help of assisted reproduction. We recommend the screening of the whole CFTR gene for these infertile couples, as part of the work-up before assisted reproduction.

PMID: 17823699 [PubMed - indexed for MEDLINE]

Cystic fibrosis: S158N (605G --> A) is a rare genetic variant found in coupling with deltaF508.

Department of Clinical Pathology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.

A single nucleotide change at codon 158 in exon 4 of the CFTR gene ABCC7 was detected in an asymptomatic individual who carried deltaF508 and had a family history of cystic fibrosis (CF). Further study, using linkage, revealed that S158N was coupled with deltaF508, both having been inherited from the same parent. The clinical implications of double mutations in the same allele are discussed.

PMID: 12820707 [PubMed - indexed for MEDLINE]