DNA Sequencing Analysis of Cystic Fibrosis Transmembrane Regulator Gene
Identifies Cystic Fibrosis-Associated Variants in the Severe Asthma
Research Program.
Abstract
Background: Heterozygote carriers of potentially pathogenic
variants in the cystic fibrosis transmembrane conductance regulator (
CFTR) gene have increased asthma risk. However, the frequency and
impact of CFTR variation among individuals with asthma is
unknown. Objective: To determine whether potentially
pathogenic CFTR variants associate with disease severity and
whether individuals with two potentially pathogenic variants exist in a
severe asthma-enriched cohort . Methods: We analyzed sequencing
data spanning a 190.5Kb region of CFTR in participants from the
Severe Asthma Research Program (SARP1-3). Potentially pathogenic, rare
CFTR variants (frequency<0.05) were classified as
CF-causing or of varying clinical consequences (VVCC) (CFTR2.org).
Regression-based models tested for association between
CFTR genotypes (0-2 potentially pathogenic variants) and severity
outcomes. Results: Of 1401 participants, 9.5% (134) had one
potentially pathogenic variant, occurring more frequently in
non-Hispanic white (NHW, 10.1% [84 of 831]) compared to African
American individuals (AA, 5.2% [22 of 426]). We found ≥2
potentially pathogenic CFTR variants in 1.4% (19); 0.5% (4) of
NHW and 2.8% (12) of AA. Potentially pathogenic CFTR variant
genotypes (≥1 or ≥2 variants) were not cumulatively associated with lung
function or exacerbations. In NHW, we found three F508del compound
heterozygotes with F508del and a VVCC (two
5T;TG12[c.1210-11T>G] and one Arg1070Trp) and a
homozygote for the VVCC, 5T;TG12. Conclusions: We found
potentially pathogenic CFTR variants within a severe
asthma-enriched cohort , including three compound heterozygote genotypes
variably associated with CF in NHW individuals. These findings provide
the rationale for CFTR sequencing and phenotyping of CF-related
traits in individuals with severe asthma.