Of the 3,443 subjects genotyped, 612 were never exposed to cocaine. These individuals were classified as “unknown” rather than “unaffected” and were removed from subsequent analyses. To correct possibly unreliable self-reported sex, we calculated the chromosome X heterozygosity for each subject and removed 31 subjects: 14 self-reported males with heterozygosity of more than 20% and 17 self-reported females with heterozygosity of less than 20%. Race was classified using STRUCTURE v2.3 [Pritchard et al., 2000] and AIMs, which stratified the remaining 2,800 subjects into two population groups: AAs and EAs. Of the 1,478 AAs, 93.78% had AA as their self-reported race. Of the 1,322 EAs, 89.71% had EA as their self-reported race. The sample included 253 self-reported Hispanics, among whom 82 reported AA origin (43 were in the African ancestry and 39 in the European ancestry clusters) and 171 reported EA origin (168 were in the European ancestry and 3 in the African ancestry clusters). We excluded other population groups from the association analysis. Association tests for AA and EA population groups were performed separately. Principal components analysis (PCA) was performed
