Genotyping and quality control procedures have been described previously (15,16, and Supplementary Methods). Briefly, cases and trios with TS or OCD and controls were randomized across plates and genotyped on the Illumina HumanHap610 SNP array (Illumina, San Diego, CA) at the Broad Institute of Harvard-MIT (Cambridge, MA) or on the Illumina HumanHap370 at the Yale Center for Genome Analysis (New Haven, CT) (Supplementary Figure S1). Eighty-eight samples were genotyped on both platforms to allow for cross-platform concordance checks. QC analyses were performed using PLINK v1.07(17) and EIGENSTRAT(18). Multi-dimensional scaling (MDS) analysis was used to exclude case-control samples of non-European descent. Remaining EU and European-derived isolate samples were separated into four strata (EU, AJ, FC, and SA) based on observed genetic ancestry (15, 16). Imputation was performed using 1000 Genomes Project data (June 2011 Data Release)(19) as the reference panel using IMPUTE v2.1.2(20) (Supplementary Methods).
