In all association analyses, principal components correlated with OCD (association p-value < 0.2) were included as covariates. We used the inverse variance method implemented in METAL (Willer, Li, and Abecasis 2010) to meta-analyze summary statistics from each subpopulation and trios for sex-stratified analysis. We performed GWAS and meta-analysis on the combined male/female sample for each subpopulation to ensure that our sex-specific QC yielded results consistent with the recently reported OCD meta-GWAS using the same data (International Obsessive Compulsive Disorder Foundation Genetics Collaborative (IOCDF-GC) and OCD Collaborative Genetics Association Studies (OCGAS) 2017). The correlation calculated using LD score regression (B. K. Bulik-Sullivan et al. 2015) between our meta-analysis and the previously published meta-analysis (International Obsessive Compulsive Disorder Foundation Genetics Collaborative (IOCDF-GC) and OCD Collaborative Genetics Association Studies (OCGAS) 2017) was not significantly different from 1 (rg = 1.052, se=0.014). Manhattan and quantile-quantile plots (Khramtsova and Stranger 2016) were used to visualize results.
