Disease characterization of people with cystic fibrosis and a minimal function mutation: Data from the Italian registry

Background: People with cystic fibrosis (pwCF) and a minimal function (MF) mutation are poorly characterized. The aim of this study was to evaluate the disease characteristics of adult and pediatric pwCF with a genotype including an MF mutation on the basis of 2018 data from the Italian CF Registry (ICFR).

Methods: This cross-sectional, descriptive analysis of CF disease characteristics included all of the pwCF with at least one MF mutation or two F508del (F) mutations, and at least one 2018 entry in the ICFR. Data concerning the disease characteristics of pwCF with an F/F genotype are provided for reference.

Findings: A total of 5501 pwCF had at least one entry in the 2018 ICFR, including 2867 whose genotype included an MF mutation; in particular, 1432 had an MF/F genotype and 1148 the F/F genotype. The most frequent F/MF genotypes were F/N1303K (n = 247, 8.6%) and F/G542X (n = 193, 6.7%). The MF/no-F patients generally had a milder phenotype (a later diagnosis, lower sweat chloride levels, better nutrition, better lung function [starting from adolescence], and a lower prevalence of chronic infections and CF-related complications) than the MF/F or F/F patients.

Interpretation: The findings of this descriptive analysis highlight the disease characteristics of pwCF with an MF-including genotype in Italy. The considered clinical outcomes of the pwCF with an F/MF genotype were not generally different from those of pwCF with an F/F genotype, but the patients with an MF/no-F genotype generally had a milder phenotype.