Nonsense mutations accelerate lung disease and decrease survival of cystic fibrosis children.

RATIONALE: Limited information is available on the clinical status of people with Cystic Fibrosis (pwCF) carrying 2 nonsense mutations (PTC/PTC). The main objective of this study was to compare disease severity between pwCF PTC/PTC, compound heterozygous for F508del and PTC (F508del/PTC) and homozygous for F508del (F508del+/+). METHODS: Based on the European CF Society Patient Registry clinical data of pwCF living in high and middle income European and neighboring countries, PTC/PTC (n = 657) were compared with F508del+/+ (n = 21,317) and F508del/PTC(n = 4254).CFTR mRNA and protein activity levels were assessed in primary human nasal epithelial (HNE) cells sampled from 22 PTC/PTC pwCF. MAIN RESULTS: As compared to F508del+/+ pwCF; both PTC/PTC and F508del/PTC pwCF exhibited a significantly faster rate of decline in Forced Expiratory Volume in 1 s (FEV1) from 7 years (-1.33 for F508del +/+, -1.59 for F508del/PTC; -1.65 for PTC/PTC, p < 0.001) until respectively 30 years (-1.05 for F508del +/+, -1.23 for PTC/PTC, p = 0.048) and 27 years (-1.12 for F508del +/+, -1.26 for F508del/PTC, p = 0.034). This resulted in lower FEV1 values in adulthood. Mortality of pediatric pwCF with one or two PTC alleles was significantly higher than their F508del homozygous pairs. Infection with Pseudomonas aeruginosa was more frequent in PTC/PTC versus F508del+/+ and F508del/PTC pwCF. CFTR activity in PTC/PTC pwCF's HNE cells ranged between 0% to 3% of the wild-type level. CONCLUSIONS: Nonsense mutations decrease the survival and accelerate the course of respiratory disease in children and adolescents with Cystic Fibrosis.

The changing face of the exocrine pancreas in cystic fibrosis: the correlation between pancreatic status, pancreatitis and cystic fibrosis genotype.

OBJECTIVES: The aims of this study were to determine the current pancreatic status of the entire cystic fibrosis (CF) population of Israel, to analyze the clinical characteristics of the pancreatic sufficient (PS) patients, and to characterize the correlation between pancreatic status, pancreatitis, and CF genotype. METHODS: The Israeli CF database includes 505 patients. These patients were defined as being PS or insufficient according to their fecal pancreatic elastase level or by coefficient fat absorption findings. Mutations were categorized as severe (DeltaF508, W1282X, G542X, S549R, N1303K, Q359K/T360K, 405+1G, and 1717) or mild/variable (3849+10 kb, D1152H, G85E, I1234V, R334W, and 5T) based on disease severity in patients carrying these mutations. Age at diagnosis, presenting symptoms, sweat-chloride concentrations, occurrence of pancreatitis, presence of diabetes, and liver disease were recorded. RESULTS: One hundred and thirty-nine (27.5%) of the CF patients were PS. None carried two mutations associated with severe disease. Over one third (34%) had normal or borderline sweat tests; 20 of these 139 patients had pancreatitis (14.3%) but none of the 366 pancreatic insufficient patients had it. Four initially PS patients became pancreatic insufficient: conversion followed several events of pancreatitis in three of them. Nasal potential differences were all pathological in 35 tested PS patients. None had either diabetes or liver disease. CONCLUSIONS: A substantial number of CF patients are PS. All of them carry at least one mild mutation enabling production of a sufficient amount of normal mRNA to maintain exocrine pancreatic function. Pancreatitis occurs only in CF patients who are PS. These patients are at risk of progressing to pancreatic insufficiency.