Pediatric population with cystic fibrosis in the centre of Portugal: candidates for new therapies

Objectives: Cystic fibrosis (CF) is a severe autosomal recessive disease that results from mutations in a gene encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein, a chloride channel. This study aims to characterize the clinical and genetic features of a cohort of pediatric people with CF (PwCF) in the center of Portugal and to determine which ones are candidates for the new drugs modulating the CFTR channel. Methods: A review of the demographic, genetic and clinical characteristics of PwCF undergoing follow-up at a CF reference center was carried out. Results: Twenty-three PwCF (12 male), with a median age of 12 years, were followed up. All patients carry the F508del mutation in at least one allele. Fifteen PwCF were F508del-homozygous, median BMI z-score was -0.13, all are pancreatic insufficient and median FEV1 value was 78.1%. These PwCF are eligible for dual therapy (lumacaftor/tezacaftor+ivacaftor) and for triple therapy (tezacaftor+ivacaftor+elexacaftor). PwCF with 711 +1G->T (n = 2), 2184insA (n = 1) mutations and a novel mutation c.3321dup (n = 1) have minimal function mutation and patients with a residual function mutation: R334W (n = 3) and P5L (n = 1) have a less severe phenotype. All these patients, because they also carry F508del mutation, are elegible to triple therapy. Conclusions: Genetic and molecular characterization of PwCF poses an important step not just for CF diagnosis and prognosis which is tightly correlated with the clinical phenotype, but also for the eligibility of CFTR modulator drugs.