This will include the (1) DRD4 gene associated with attentiondeficit/ hyperactivity disorder, located in a locus that underwent a positive selection; the (2) GABRB2 gene, a gene associated with schizophrenia and recently reported as the target of a positive selection; (3) MARK1, a candidate gene for autism that was reported as displaying a signature of adaptative evolution in the human lineage, and (4) the ADH and ALDH2 genes which are associated with alcoholism, and for which evidence of positive selection was identified in the human lineage since the divergence between humans and chimpanzees.
GABRB2 and GRIN2B genotypes were associated with significant regional differences in the pattern of beta subunit expression, but this was not influenced by alcoholism status.
Association of the GABRB2 1412T allele with alcohol dependence was detected in both populations (Finns, P = .01; Southwestern Native Americans, P = .008), and the GABRA6 1519T allele was associated in both Finns (P = .01) and Southwestern Native Americans (P = .03).