Cystic fibrosis (CF) is a monogenic disorder leading to multi-organ system dysfunction, with the primary cause of morbidity and mortality being lung disease. Mutations in CFTR result in defective ion channel transport leading to hyperviscous mucus, airway infection, inflammation and lung function decline. While the Phe508del mutation is the most common CFTR mutation in North American people with CF, it is well known that there is a broad range of lung disease severity even amongst Phe508del homozygotes, including twins/siblings. Heritability analyses showing the relative contribution of non-CFTR modifier genes in such differences in phenotype, have led to our genomic and transcriptomic studies of gene modifiers in CF. Complementary to two international CF GWAS studies, this study was performed to a) determine differential expression of genes relative to a quantitative lung disease severity phenotype score (KNoRMA; as used in CF GWAS studies) and b) to assess expression quantitative trait loci. To better understand genetic modification of CF lung disease severity, we analyzed gene expression (transcriptomic) profiles by mRNA sequencing from nasal mucosal biopsy specimens of 134 people with CF. Each study participants was characterized for CF lung disease severity phenotype by averaging three years of lung function data (forced expiratory volume in 1 second; FEV1), normalized to a CF-specific reference population matching for age, sex, and height. Participants completed nasal lavage and nasal curettage mucosal sampling, with directed sampling to the inferior nasal turbinate, a well validated surrogate for cellular characteristics and CFTR function of the lower CF airways. Participants were further invited to complete a second set of these sampling procedures for validation analysis. Specimen and concurrent clinical data collection occurred across four North American study sites and nasal mucosal specimens were subjected to RNASeq analysis. These data were to be made available in the dbGaP. Our association analyses of gene expression relative to quantitative CF lung disease phenotype, taken together with previously identified GWAS signals, identified biological pathways correlated with CF lung disease pathogenesis. Our further association analyses of gene expression relative to single nucleotide polymorphism variation at significant CF GWAS loci further identified potential mechanisms of genetic variants associated with CF lung disease. This resource is intended to aid researchers in characterizing airway mucosal gene expression from the CF airways for the purpose of gene expression profiling in CF and in muco-obstructive airways disease.

Cystic Fibrosis Nasal Epithelium Gene Expression by RNAseq

Airway Mucosal Host Defense Is Key to Genomic Regulation of Cystic Fibrosis Lung Disease Severity