We conducted a GWAS meta-analysis of 28 European-ancestry OCD case-control cohorts, comprising 53,660 cases and 2,044,417 controls (effective sample size ~210,000 individuals). Ascertainment of cases varied across cohorts: OCD diagnosis was determined (i) by a healthcare professional in a clinical setting (18 cohorts, n = 9,089 cases), (ii) from health records or biobanks (7 cohorts, n = 9,138 cases), (iii) in a clinical setting or from health records with the additional characteristic that all OCD cases were primarily collected for another psychiatric disorder (3 cohorts, n = 5,266 cases), or (iv) by self-reported diagnosis in a consumer-based setting (23andMe, Inc., n = 30,167 cases). Cohort details, including phenotypic assessment, quality control, and individual cohort GWAS analyses are described in Supplementary Note 2 and Supplementary Table 1. We identified 30 independent (defined in Supplementary Note 3) loci among the 1,672 SNPs that exceeded the genome-wide threshold for significance (P < 5 × 10−8; Manhattan plot in Fig. 1, regional association plots and forest plots in Supplementary Figs. 231, and a list of all independent genome-wide significant SNPs in Table 1 with
