Genome-wide association tests were performed on the imputed dosage data of GWAS2 and TIC samples separately in PLINK1.9, using logistic regression under an additive model with the first four MDS components and any additional MDS components associated with Tourette case-control status at p<0.05 included as covariates. A linear mixed model was used for the GWAS2 FAM association analysis in MMM v.1.0 (16) to control for familial relatedness. GWAS1 samples were re-imputed as described above; association tests were performed in four ancestry-based strata: Non-isolate European (GWAS1_EU), Ashkenazi Jewish (GWAS1_AJ), French Canadian (GWAS1_FC), and GWAS1 TIC (GWAS1_TIC) (Table S2).
