Clinical characteristics of 16 cystic fibrosis patients with the missense mutation R334W, a pancreatic insufficiency mutation with variable age of onset and interfamilial clinical differences

Abstract

We present the genotype/phenotype correlation analysis for 16 cystic fibrosis (CF) patients who carry mutation R334W. Current age and age of diagnosis was significantly higher in the R334W/any-mutation group (P < 0.05 and P < 0.01), compared with the Δ508/Δ508 group. A slightly, but not significantly, worse lung function was found in the R334W/any-mutation group, when compared with the Δ508/Δ508 patients. The proportion of patients with lung colonization with bacterial pathogens was slightly, but not significantly, higher in the R334W/any-mutation group (71.4%), compared with the Δ508/Δ508 or R334W/Δ508 groups (55.5%). None of the R334W patients had meconium ileus but 60% were pancreatic insufficient (PI), a significantly lower proportion (P ≪ 0.001) than Δ508/Δ508 patients. Two R334W/N1303K compound heterozygous sisters were PI but discrepant for lung function. Two groups of three sibs with genotype R334W/Δ508 showed interfamilial discordant clinical data for lung and pancreatic function. The data provided here for mutation R334W demonstrate that this mutation is responsible for a less severe form of CF than Δ508. Interfamilial differences for PI and lung function suggest that other factors, viz. genetic, environmental and medical, contribute to the wide spectrum of clinical differences observed in CF patients with the same CF transmembrane conductance regulator genotypes.