Abstract
Background: The clinical course of cystic fibrosis (CF) patients with the Gly551Asp mutation (class III) is not well characterised, particularly in terms of structural lung disease. Data on whether the clinical severity of Gly551Asp patients differs from Phe508del homozygous patients is divergent.
Aims: We aimed to compare computed tomography (CT) outcomes in patients with the Gly551Asp mutation against the most common CF mutation, Phe508del ("severe" class II genotype). We hypothesised that structural lung disease will be less severe in Gly551Asp patients.
Methods: All patients in the AREST CF cohort with the Gly551Asp mutation and one severe genotype, with accompanying PRAGMA-CF scores were included. Age-matched CT scans from Phe508del homozygous CF patients were randomly selected. The extent of total disease (%Dis) and trapped air (%TA) were determined from the PRAGMA score. Linear mixed model analysis was used to compare CT outcomes of both genotype groups, accounting for age and repeated visits with p<0.05 considered statistically significant.
Results: Seventeen patients with the Gly551Asp mutation (44 CT scans) and 136 homozygous Phe508del patients (348 CT scans) were included, with median (range) age of 3 (0-11) years. Differences in %Dis and %TA between Gly551Asp and homozygous Phe508del patients were -0.11(-0.79,0.57) p=0.750 and 0.13(-2.47,2.72) p=0.923, respectively.
Conclusions: A significant difference in structural lung disease was not detected between both groups, suggesting that patients with the Gly551Asp mutation have as severe lung disease as patients with severe genotypes in childhood. Therefore, Gly551Asp patients could be selected for more intensive clinical follow-up.
- Copyright ©the authors 2017