Prevalence of ΔF508 mutation in the cystic fibrosis transmembrane conductance regulator gene among cystic fibrosis patients from a Brazilian referral center

To verify the presence of ΔF508 mutation in the cystic fibrosis transmembrane conductance regulator gene among patients with cystic fibrosis diagnosed by the sweat test for sodium and chlorine and followed at the Pediatric Pneumology Outpatient Clinic of Universidade Estadual de Campinas, Brazil, a referral center for the treatment of cystic fibrosis. The study analyzed 167 DNA samples from cystic fibrosis patients. Patients' genotype was determined by polymerase chain reaction, and allele and genotype frequencies of ΔF508 mutation were calculated. The genotype frequencies found for -/-, ΔF508/-, and ΔF508/ΔF508 genotypes were respectively: 43.7% (73 patients), 32.9% (55 patients), and 23.4% (39 patients). Of the 334 alleles analyzed, we observed a frequency of 201 (60.18%) alleles for the absence of ΔF508 mutation and of 133 (39.82%) for the presence of ΔF508 mutation. Hardy-Weinberg equilibrium was calculated, obtaining a chi-square value = 16.34 (p ≤ 0.001). The study population was out of equilibrium. The expected values for -/-, ΔF508/-, and ΔF508/ΔF508 genotypes were respectively: 32.22% (60.48 patients), 47.93% (80.04 patients), and 15.86% (26.48 patients). In the analyzed population, ΔF508 mutation was less prevalent than the allele without this mutation. The frequency observed in this study was similar to that from other areas in Brazil and in the world, mainly due to the predominantly Caucasian origin of the population included in the study.