p.F508del in a heterogeneous cystic fibrosis population from Minas Gerais, Brazil (original) (raw)
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Low Frequency of the ΔF508 Mutation of the CFTR Gene in a Highly Admixed Population in Bahia, Brazil
Human Biology, 2007
Cystic fibrosis (CF) is the most common autosomal recessive disease in the European (Caucasian) population, with an incidence of 1:2,000 to 1:8,000. The F508 mutation (66%) is predominant among more than 1,300 different mutations of the CFTR gene. The population of the state of Bahia, in northeastern Brazil, is highly admixed (mainly African and Portuguese descendants), and so far, no study has been carried out to assess the molecular basis of CF in this population. We determined the F508 mutation frequency in 503 individuals from the general population of Salvador, the capital of the state of Bahia, and in 144 CF patients from several cities in Bahia. In the general population samples we found 4 individuals heterozygous for the F508 mutation (allele frequency of 0.4%). This frequency was lower than that found in the state of Rio de Janeiro, in southeastern Brazil, and similar to that reported for the state of Paraná, in the far south. In the CF patients we found 9 heterozygous individuals and 8 homozygous individuals (allele frequency of 8.68%) for the F508 mutation. This frequency is considerably lower than the average frequency of CF in the world population and in the Brazilian CF population of European ancestry (47%). These data could be explained by the intense admixture among the population in Bahia, and they suggest a heterogeneous molecular basis for CF in this area of Brazil. Cystic fibrosis (CF) is the most common autosomal recessive disease in the European (Caucasian) population, with an occurrence rate of 1 of every 2,000 live births. The clinical features of CF appear predominantly in the respiratory and digestive systems (Noone et al. 1994). In 1989 the gene responsible for CF, the cystic fibrosis transmembrane conductance regulator (CFTR), was cloned. The CFTR gene is located on chromosome 7q31, expands for 250 kb, and contains 27 exons. It codifies a protein of 1,480 amino acids. So far, more than 1,300 mutations have been identified, and
Human Mutation, 2001
Cystic fibrosis (CF) is the most common autosomal recessive disease in the Caucasian population. The disease can be caused by one of the more than 900 different mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. However, the deletion of the phe508-codon is the most prevalent mutation observed. Our aim was to perform a screening for this mutation (∆ ∆ F508, or F508del) in the population of Mendoza, Argentina. For the screening, 1,000 blood samples were obtained from CF asymptomatic individuals and combined into 100 pools each containing 10 different blood samples. Pools containing at least one F508del carrier were detected by heteroduplex formation during the PCR amplification of exon 10. The PCR was designed to introduce a recognition site for a restriction enzyme that confirmed the presence of the deletion F508del in the positive pools. The results with this simple method indicate a frequency of carriers in the Mendoza population of 2.1% (1.3%-3.2, 95% confidence limits). The observed frequency of carriers is similar to that reported for European populations.
CFTR gene: molecular analysis in patients from South Brazil
Molecular Genetics and Metabolism, 2003
Cystic fibrosis (CF) is the most common genetic disease among Caucasians. The CF gene, named cystic fibrosis transmembrane conductance regulator (CFTR), codifies a protein that acts as a channel through the epithelial membrane. The present work aimed (1) to detect sequence alterations in the nucleotide binding regions and at the membrane spanning domain of the CFTR gene and (2) to detect the following frequent mutations R347P, R347H, R334W, and Q359K (located in exon 7), DF508 (located in exon 10), G542X, G551D, R553X, and S549N (located in exon 11), W1282X (located in exon 20), and N1303K (located in exon 21). Seventyseven unrelated CF patients were analyzed, who were previously diagnosed and currently under treatment at the Pneumology Service of our hospital. Regions of interest were amplified by PCR using specific primers. Each sample was analyzed by a nonradioactive single-stranded conformational polymorphism (SSCP) analysis technique and restriction enzyme digestion. The DF508 mutation was found in 48.7% of the alleles. Frequencies of G542X, R334W, R553X, and W1282X mutations in our population were 3.25, 1.3, 0.65, and 0.65%, respectively. No alleles were found to carry mutations G551D, R334W, R347P, R347H, Q359K, S549N, and N1303K, which were included in the screening protocol. This study allowed the characterization of 84 out of 154 CF mutant alleles (54.5%). The incidence of main CF mutations analyzed was similar to that of the south European population. Mutation data presented here will be useful for designing new DNA testing strategies for CF in South Brazil.
Journal of Cystic Fibrosis, 2008
Cystic Fibrosis (CF) is one of the most common single-gene defects in European descent populations with an incidence of about 1 in every 2500 live births and carrier frequency of approximately 1 in 25. The most common mutation at the CF transmembrane conductance regulator (CFTR) gene is a deletion (p.F508del) of the phenylalanine codon 508; its frequency, however, is not the same throughout the world. The purpose of this paper is to document an application of a two-tier survey design in different states of Brazil, from which regional differences of the incidence of CF and frequency of CF-causing mutation(s) carriers can be for the first time estimated. We present data on genotype distributions in reference to p.F508del mutation in samples of newborns, adult controls and CF patients from five Brazilian states, in which a total of 2683 newborns born to Brazilian white parents and 500 African-Brazilians adult controls were screened, as well as 300 CF patients (262 European descents and 38 African descents) were genotyped. Our results suggest that the CF-incidence in different parts of Brazil may differ by almost 20-fold. For the five different states as a whole, nearly 48% of the CF-alleles carry the p.F508del mutation, which places the estimates of disease incidence and carrier frequencies for the Brazilian European descents as 1 in 7576 live births and 2.3%, respectively. The implications for prevention of CF and other rare Mendelian diseases through such surveys of mutation screening are discussed.
Spectrum of Mutations in the CFTR Gene in Cystic Fibrosis Patients of Spanish Ancestry
Annals of Human Genetics, 2007
We analyzed 1,954 Spanish cystic fibrosis (CF) alleles in order to define the molecular spectrum of mutations in the CFTR gene in Spanish CF patients. Commercial panels showed a limited detection power, leading to the identification of only 76% of alleles. Two scanning techniques, denaturing gradient gel electrophoresis (DGGE) and single strand conformation polymorphism/hetroduplex (SSCP/HD), were carried out to detect CFTR sequence changes. In addition, intragenic markers IVS8CA, IVS8-6(T)n and IVS17bTA were also analyzed. Twelve mutations showed frequencies above 1%, p.F508del being the most frequent mutation (51%). We found that eighteen mutations need to be studied to achieve a detection level of 80%. Fifty-one mutations (42%) were observed once. In total, 121 disease-causing mutations were identified, accounting for 96% (1,877 out of 1,954) of CF alleles. Specific geographic distributions for the most common mutations, p.F508del, p.G542X, c.1811 + 1.6kbA > G and c.1609delCA, were confirmed. Furthermore, two other relatively common mutations (p.V232D and c.2789 + 5G > A) showed uneven geographic distributions. This updated information on the spectrum of CF mutations in Spain will be useful for improving genetic testing, as well as to facilitate counselling in people of Spanish ancestry. In addition, this study contributes to defining the molecular spectrum of CF in Europe, and corroborates the high molecular mutation heterogeneity of Mediterranean populations.
Human Biology, 2005
To define mutations present in 23 exons and flanking intronic sequences of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 95 patients from Rio de Janeiro, Brazil, we carried out single-strand conformation polymorphism analysis and automated direct sequencing. Mutation detection was achieved in 45% of the alleles presented, and complete genotyping (two mutated alleles) was accomplished in 34.7% of the patients. Twenty patients (21.1%) were found to carry only one mutation, whereas mutated alleles could not be observed in 42 patients (44.2%). Eleven mutations were found, of which four were characterized as rare mutations: P205S (1.05%), Y1092X (0.53%), S549R (0.53%), and S4X (0.53%). The DF508 mutation in this population sample showed a frequency of 28.42%. The low number of individuals (10 of 95; 10.5%) with compound heterozygous (DF508/non-DF508) genotypes could indicate the presence of another severe mutation leading to the premature death of these individuals. In 4 of the aforementioned 10 individuals with compound heterozygous genotypes, the D-7-2-1-2 (XV2c-KM19-IVS6a-TUB9-M470-T854) haplotype was defined.
Frequency of common CFTR gene mutations in Venezuelan patients with cystic fibrosis
Investigación clínica, 2014
Mutations in the CFTR gene in Cystic Fibrosis (CF) patients have geographic differences and there is scant data on their prevalence in Venezuelan patients. This study determined the frequency of common CFTR gene mutations in these patients. We amplified and sequenced exons 7, 10, 11, 19, 20 and 21, which contain the most common CFTR mutations, from 105 Venezuelan patients in the National CF Program. Eleven different mutations were identified, four with frequencies greater than 1%: p.Phe508del (26,17%), p.Gly542X (3,33%), p.Arg334Trp (1,43%) and p.Arg1162X (1.43%). No mutations were found in 63.3% of patients. This report represents the largest group of Venezuelan CF patients ever examined and includes a wider mutation panel than has been previously studied in this population. Southern European CFTR mutations predominate in the Venezuelan population, but a high percentage of the causative alleles remain unidentified.
Analysis of 31 CFTR mutations in 55 families from the south of Spain
Early Human Development, 2001
We carried out a molecular analysis of 350 chromosomes from 55 families originating from the South of Spain (Andalucia) who were diagnosed with cystic fibrosis (CF). We used polymerase chain reaction, followed by an oligonucleotide ligation assay (OLA) and sequence-coded separation using capillary electrophoresis. A frequency of 43.5% for DF508 was found, making it the most common CF mutation in our sample. Seven more mutations (G542X, R334W, R1162X, 2789 + 5G ! A, R117H, DI507 and W1282X) were detected and accounted for 24.7% of the total. The remaining mutations (31.8%) were undetectable with the methodology used in this study. D
PLOS ONE, 2015
Cystic fibrosis (CF) is an autosomal recessive inherited life-threatening disorder that causes severe damage to the lungs and the digestive system. In Palestine, mutations in the Cystic Fibrosis Transmembrane Conductance Regulator gene (CFTR) that contributes to the clinical presentation of CF are ill defined. A cohort of thirty three clinically diagnosed CF patients from twenty one different Palestinian families residing in the central and southern part of Palestine were incorporated in this study. Sweat chloride testing was performed using the Sweat Chek Conductivity Analyzer (ELITECH Group, France) to confirm the clinical diagnosis of CF. In addition, nucleic acid from the patients' blood samples was extracted and the CFTR mutation profiles were assessed by direct sequencing of the CFTR 27 exons and the intron-exon boundaries. For patient's DNA samples where no homozygous or two heterozygous CFTR mutations were identified by exon sequencing, DNA samples were tested for deletions or duplications using SALSA MLPA probemix P091-D1 CFTR assay. Sweat chloride testing confirmed the clinical diagnosis of CF in those patients. All patients had NaCl conductivity >60mmol/l. In addition, nine different CFTR mutations were identified in all 21 different families evaluated. These mutations were c.1393-1G>A, F508del, W1282X, G85E, c.313delA, N1303K, deletion exons 17a-17b-18, deletion exons 17a-17b and Q1100P. c.1393-1G>A was shown to be the most frequent occurring mutation among tested families. We have profiled the underling mutations in the CFTR gene of a cohort of 21 different families affected by CF. Unlike other studies from the Arab countries where F508del was reported to be the most common mutation, in southern/ central Palestine, the c.1393-1G>A appeared to be the most common. Further studies are needed per sample size and geographic distribution to account for other possible CFTR genetic alterations and their frequencies. Genotype/phenotype assessments are also recommended and finally carrier frequency should be ascertained.