Expandiendo el espectro mutacional en pacientes chilenos con fibrosis quística

Abstract

Introduction: Cystic Fibrosis (CF) is an autosomal recessive disease and affects 1 in 8000-9000 newborns in Chile. More than 1,800 different mutations have been identified in CFTR gene. The available molecular diagnosis analyzes the 36 most frequent mutations in Caucasian population, with an overall detection rate of80-85%, but with a much lower detection rate in Chilean patients of 42%. To analyze which other mutations are present in Chilean patients, we conducted an extensive analysis by direct DNA sequencing of coding sequences of the CFTR gene. Methods: Forty eight Chilean patients with clinical diagnosis of CF and one mutated allele in the CFTR gene identified, were studied by direct sequence analysis of exons 6, 7, 14, 19 and 20 of the CFTR gene. Results: We found 3 different mutations in 14 cases that had not been previously identified in Chilean patients. Four patients have a deletion of two nucleotides (c.2462_2463delGT/p.Ser821ArgfsX4) in exon 14, which is predicted to cause a frameshift and a premature stop codon. Eight patients have c.3196C>T mutation in the exon 20 and 2 cases has c.3039delC mutation in the exon 19. Both mutations had been previously described in other populations. Discussion: The identification of these mutations has notably increased the detection rate in our patients. Adapting the molecular diagnosis method by including these three mutations should increase the CF detection rate in Chilean patients. This analysis will improve CF diagnosis and allow an adequate genetic counseling to the families.