The study group included 47 participants [mean age 29.74±SD 10.8 years, 26 females (55%)] who were recruited from the community and were without personal history of a DSM-IV Axis I Disorder confirmed by the Structured Clinical Interview for DSM-IV Axis I Disorders Version 2.0 (SCID) (2). No subject was taking medications with potential central nervous system effects or had a history of psychiatric or neurological disorder, head trauma with loss of consciousness over five minutes, or major medical disorder. Sixty-two percent of the participants were European-American (EA), 17% were African-American (AA), 13% were Asian, 4% were Hispanic and 4% were biracial. After a complete description of the study, written informed consent was obtained from all participants in accordance with the human investigation committees of the Yale School of Medicine and Department of Veterans Affairs. Subjects were divided into two subgroups for each SNP: those homozygous for the more frequent allele and “carriers” of the less frequent allele who were heterozygous and homozygous for that allele. For SNP-1, subjects were divided into those homozygous for G allele and “A carriers” with
