Cho, M.H.

Abstract Background:Chronic obstructive pulmonary disease (COPD) is a major global health burden, with genome-wide association studies explaining only a fraction of its heritability. Recent advancements, including large-scale, multi-ancestry whole-genome sequencing and a focus on severe, early-onset cases, offer promising avenues to identify additional COPD-related variants. Furthermore, recent studies show that adjusting for polygenic risk scores (PRS) enhances statistical power to detect rare variants, advancing efforts to understand COPD's genetic basis. Methods:We performed a whole genome sequencing association study of severe, early-onset COPD (FEV1 < 50%, age ≤ 55), FEV1 and FEV1/FVC in eight population-based studies (ARIC, CARDIA, CFS, CHS, FHS, HCHS/SOL, JHS, MESA) and seven COPD-enriched studies (COPDGene, ECLIPSE, Boston Early-Onset COPD Study, LTRC, TCGS (Poland), ICGN, SPIROMICS). We performed single-variant analyses using regenie software, applying a genome-wide significance threshold of P < 5.0 x 10-8. For rare variant set (MAF <1%) analysis, we annotated variants with loss of function or deleterious missense using WGS Annotator and prediction tools LOFTEE, SIFT, and PolyPhen2, then analyzed these variants with SKATO-ACAT method in regenie, adjusting for covariates including sex, sequencing center, and principal components of ancestry. We additionally evaluated adjusting the analyses for PRSs for lung function traits. Results: We analyzed 53,028 participants including 34,751 European, 12,508 African, 1,088 Latino American, and 674 East Asian ancestry. Across cohorts, we analyzed 5,063 severe (FEV1 < 50%) COPD cases, among whom 1,103 were early-onset (age ≤ 55). Excluding variants within 1 Mbp of known variants, single-variant analysis identified 68 novel associations (MAC ≥ 30), with 8 common associations (MAF ≥ 1%) in 6 genomic regions. Our most significant novel association for severe early-onset COPD was rs74297390 (intergenic to POM121L12, MAF = 9.6%, Beta = 0.41, P = 3.5 x 10-8). For FEV1 and FEV1/FVC ratio, variants near DKK2 and AKR1E2 were significantly associated and were replicated in an independent dataset (Shrine et al., 2019). DKK2 is an antagonist in the Wnt pathway. In a preliminary variant set analysis, CHRM3-AS1 was associated with severe early-onset COPD, GPAT with FEV1, and COL8A1I and HMCN1 with FEV1/FVC. With PRS adjustment, ST6GALNAC5 was associated with FEV1/FVC. Conclusions: In a whole genome sequencing study of lung function and severe early-onset COPD, we identified new loci for COPD-related phenotypes, including two novel loci that replicated in an independent dataset. Ongoing work involves variant set-based analyses with additional covariate adjustments, as well as PRS adjustments for binary traits.

Abstract Introduction / Rationale Mucus plugs (MPs) on chest computed tomography (CT) are associated with increased respiratory symptoms, worse lung function, and elevated mortality and acute exacerbations among individuals with GOLD2-4 COPD. Whether mucus plug distribution in the upper versus lower lobes differentially impacts future acute exacerbations (AEs) has been incompletely explored. Methods Data from current and former tobacco users, ages 40-80, with ≥10 pack-years, at the enrollment visit in COPDGene were analyzed. MPs were visually-assessed on chest CTs using a sequential reading system; the MP score was calculated as the number of bronchopulmonary segments with plugs (range 0-18). Among subjects with MPs, the percent of lower lobe MPs (%LLMPs) was calculated as the number of bronchopulmonary segments in the right and left lower lobes divided by the total number of bronchopulmonary segments (range 0-100%). Moderate-to-severe AEs were assessed prospectively biannually for up to 15.5 years. Zero-inflated Poisson regression, adjusting for age, sex, BMI, race, smoking status, pack-years, FEV1% predicted, history of AEs (year prior to enrollment), and clinical center assessed the relationship between %LLMPs, total MPs, and prospective AEs; duration of follow-up was included as the offset. Subgroup analyses by lung function category (GOLD0, GOLD 1-4 COPD, and Preserved Ratio Impaired Spirometry, PRISm) were also performed using the same model. Results Among 10,198 tobacco-exposed individuals, 9,406 subjects (mean age 59.7±9.0, 53.4% male, 68% non-Hispanic white) had chest CT scans scored for MPs. The overall prevalence of MP>0 was 30.4%, with an average MP score of 0.78±1.88 and average %LLMP of 48%±39%. The prevalence of MPs varied by lung function category (20.1% GOLD0, 26.2% PRISm, 40.8% COPD) as did the mean MP score (0.28±0.93 GOLD0, 0.49±1.38 PRISm, 1.30±2.42 COPD) (Figure 1). The %LLMP also varied by lung function category (33%±39% GOLD0, 38%±37% PRISm, 57%±37% COPD). Among subjects with MPs>0 (n=2,857), higher %LLMP was associated with a significantly increased risk for future AEs (adjusted rate ratio (aRR) [95%CI]= 1.11[1.05-1.17]; Figure 1). Subgroup analyses by lung function category supported a significant association between increased %LLMP and future AEs in GOLD0 (aRR 1.45 [1.25-1.69]), but not in the COPD or PRISm subgroups (Figure 1). Conclusions A higher proportion of lower lobe mucus plugs is significantly associated with increased risk for future AEs among tobacco-exposed persons. Despite having the lowest burden of MPs, the highest risk for prospective AEs with increasing %LLMP was observed in the subgroup with normal spirometry (GOLD0).