Spectrum of CFTR gene sequence variants in a northern Portugal population

In Portugal, the spectrum of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene variants is not known. The main objective of this work was to determine the type and frequency of CFTR variants in a sample from northern Portugal by the complete analysis of the CFTR coding sequencing performed in 512 Portuguese children. A total of 30 different CFTR sequence variants, already reported as cystic fibrosis (CF) or CFTR related disorders variants, were detected. Ninety-two children (18.0%; 95%CI: 14.7-21.6) were found to be carriers of one sequence variant and 8 (1.6%; 95%CI: 0.7-3.1) had two sequence variants. Taking into consideration only variants that may cause CF when combined with a pathogenic CF variant, the CF pathogenic variant carrier frequency was 3.3% (95%CI: 1.9-5.3). One (0.2%; 95%CI: 0.01-0.7) child presented two CF pathogenic variants.

The majority of CFTR variants detected have been associated with a less severe CF phenotype. A wide spectrum of CFTR variants was identified, confirming the highest CFTR allelic heterogeneity previously reported in Mediterranean country. Additionally, better knowledge about the CFTR sequence variation spectrum may contribute to more efficient genetic testing in the Portuguese population.