Frequency of 8 CFTR gene mutations in cystic fibrosis patients in Minas Gerais, Brazil, diagnosed by neonatal screening

ABSTRACT

The nature and frequency of cystic fibrosis mutations in Brazil is not uniform due to the highly varied ethnic composition of the population. The average frequency of the F508del mutation has been reported to be 48.6 percent. Other common mutations in Brazil are G542X, R1162X, and N1303K. The aim of this study was to analyze the frequency of 8 mutations (F508del, G542X, R1162X, N1303K, W1282X, G85E, 3120+1G>A, and 711+1G>T) in a sample of 111 newborn patients with cystic fibrosis diagnosed by the Cystic Fibrosis Neonatal Screening Program of Minas Gerais State. The mutations were tested by allele-specific oligonucleotide PCR with specially designed primers. An allele frequency of 48.2 percent was observed for the F508del mutation, and allele frequencies of 5.41, 4.50, 4.05, and 3.60 percent were found for the R1162X, G542X, 3120+1G>A, and G85E mutations, respectively. The genotypes obtained were in Hardy-Weinberg equilibrium. These data demonstrate that the 8-mutation panel studied here has extensive coverage (68 percent) for the cystic fibrosis mutations in Minas Gerais. These data improve our knowledge of cystic fibrosis in Brazil, particularly in this region. In addition, this investigation contributed to the establishment of a sensitive and population-specific mutation panel, which can be helpful for molecular diagnosis of cystic fibrosis.