Individual ancestry-stratified case-control genome-wide association analyses (EU, AJ, FC, and SA) and one case/pseudo-control analysis using the OCD trios were performed in PLINK (17) using logistic regression under an additive model with significant subpopulation-specific MDS axes included as covariates to control for residual population stratification (Figure S2). These population-specific analyses were then combined in a fixed-effects model meta-analysis using case-weighting in METAL (21). SNPs with p-values <10−5 were annotated with details including their genomic region and location, allele frequencies, nearby genes and p-values from individual TS and OCD GWAS studies. Heterogeneity tests were also conducted to assess subpopulation differences using Cochran’s Q and I2 statistics. As is standard in GWAS for complex traits, a genome-wide threshold of p<5×10−8 was considered statistically significant evidence of association (22, 23).
