Morbidity and mortality in carriers of the cystic fibrosis mutation CFTR Phe508del in the general population

Abstract

Cystic fibrosis (CF) is caused by autosomal-recessive inheritance of a dysfunctional cystic fibrosis transmembrane conductance regulator (CFTR), up to 90% due to Phe508del mutation in the CFTR gene. We tested the hypothesis that CFTR Phe508del carriers have increased morbidity and mortality versus non-carriers in the general population. We genotyped 108035 randomly selected white Danish individuals from the Copenhagen General Population Study (aged from 20–100 years) for CFTR Phe508del mutation (rs113993960). Risk of chronic bronchitis and airflow limitation was assessed cross-sectionally. Overall survival and risk of bronchiectasis, lung cancer, pneumonia, chronic rhinosinusitis, airway bleeding, spontaneous pneumothorax, respiratory failure, acute and chronic pancreatitis, liver cirrhosis, ileus, gastric and colorectal cancer, and male infertility were assessed prospectively during up to 15 years of follow-up (median: 9 years). A single individual was excluded due to homozygosity for CFTR Phe508del and known CF. No other individuals had diagnosed CF at baseline examination or during follow-up. Among the resulting 108034 individuals, 105176 (97%) were non-carriers and 2858 (3%) were carriers (i.e. were heterozygous for CFTR Phe508del). Overall survival was similar between carriers and non-carriers. Compared to non-carriers and with multivariable adjustment, carriers had an odds ratio (OR) of 1.31 (95% CI 1.16–1.48) for chronic bronchitis, a hazard ratio (HR) of 1.88 (95% CI 1.03–3.45) for bronchiectasis and 1.52 (95% CI 1.12–2.08) for lung cancer. Carriers did not differ from non-carriers concerning lung function or any other morbidity outcomes as mentioned above. In the general population, carriers of CFTR Phe508del have a normal lifespan but an increased risk of chronic bronchitis (1.3-fold), bronchiectasis (1.9-fold) and lung cancer (1.5-fold).