Novel idiopathic pulmonary fibrosis susceptibility variants revealed by deep sequencing

Background: Specific common and rare single nucleotide variants (SNVs) increase the likelihood of developing sporadic idiopathic pulmonary fibrosis (IPF). We performed target enriched sequencing on three loci previously identified by a genome-wide association study to gain a deeper understanding of the full spectrum of IPF genetic risk and performed a two-stage case-control association study. Methods: A total of 1.7 Mb of DNA from 181 IPF patients was deep sequenced (100X) across 11p15.5, 14q21.3, and 17q21.31 loci. Comparisons were performed against 501 unrelated controls and replication studies were assessed in 3,968 subjects. Results: Thirty-six SNVs were associated with IPF susceptibility in the discovery stage (p<5.0x10-8). After meta-analysis, the strongest association corresponded to rs35705950 (p=9.27x10-57) located upstream from the mucin 5B (MUC5B) gene. Additionally, a novel association was found for two co-inherited low-frequency SNVs (<5%) in MUC5AC gene, predicting a missense amino acid change in mucin 5AC (lowest p=2.27x10-22). Conditional and haplotype analyses in 11p15.5 supported the existence of additional contribution of MUC5AC variants to IPF risk. Conclusions: This study reinforces the significant IPF associations of these loci and implicates MUC5AC as another key player in IPF susceptibility

Overlap of genetic risk between interstitial lung abnormalities and idiopathic pulmonary fibrosis

Rationale Interstitial lung abnormalities (ILA) are associated with the highest genetic risk locus for IPF; however, the extent to which there is additional overlap with IPF, or unique associations among those with ILA is not known. Objectives To perform a genome-wide association study (GWAS) of ILA. Methods: ILA and the subpleural-predominant subtype were assessed on chest computed tomography (CT) scans in the AGES, COPDGene, Framingham Heart, ECLIPSE, MESA, and SPIROMICS studies. We performed a GWAS of ILA in each cohort and combined the results using a meta-analysis. We assessed for overlapping associations in independent GWASs of IPF. Measurements and Main Results Genome-wide genotyping data were available in 1,699 ILA cases and 10,274 controls. The MUC5B promoter variant rs35705950 was significantly associated with both ILA (p=2.6x10-27) and subpleural ILA (p=1.6x10-29). We discovered novel genome-wide associations near IPO11 (rs6886640, p=3.8x10-8 ) and FCF1P3 (rs73199442, p=4.8x10-8 ) with ILA, and HTRE1 (rs7744971, p=4.2x10-8 ) with subpleural-predominant ILA. These novel associations were not associated with IPF. Of 12 previously reported IPF GWAS loci, 5 (DPP9, DSP, FAM13A, IVD, and MUC5B) were significantly associated (p<0.05/12) with ILA. Conclusions In a GWAS of ILA in six studies, we confirmed the association with a MUC5B promoter variant and found strong evidence for an effect of previously described IPF loci; however, novel ILA associations were not associated with IPF. These findings highlight common and suggest distinct genetically-driven biologic pathways between ILA and IPF

Genome-wide association analyses for lung function and chronic obstructive pulmonary disease identify new loci and potential druggable targets

Chronic Obstructive Pulmonary Disease (COPD) is characterised by reduced lung function and is the third leading cause of death globally. Through genome-wide association discovery in 48,943 individuals, selected from extremes of the lung function distribution in UK Biobank, and follow-up in 95,375 individuals, we increased the yield of independent signals for lung function from 54 to 97. A genetic risk score was associated with COPD susceptibility (odds ratios per standard deviation of the risk score (~6 alleles) (95% confidence interval) 1.24 (1.20-1.27), P=5.05x10^-49) and we observed a 3.7 fold difference in COPD risk between highest and lowest genetic risk score deciles in UK Biobank. The 97 signals show enrichment in development, elastic fibres and epigenetic regulation pathways. We highlight targets for drugs and compounds in development for COPD and asthma (genes in the inositol phosphate metabolism pathway and CHRM3) and describe targets for potential drug repositioning from other clinical indications