Table 1.

Genes from which SNPs were chosen for analyses.

Gene	Location	SNPs	Role in Dopamine (DA)
DRD3	3q13.3	32	codes D3 subtype of DA receptors
SLC6A3 (a.k.a. DAT1)	5p15.3	35	DA transporter that mediates reuptake of DA from the synapse
DRD1	5q35.1	9	codes D1 subtype of DA receptors
DDC	7p12.2	81	codes a protein that converts L-DOPA to DA
DBH	9q34	37	converts DA to norepinephrine
DRD4	11p15.5	4	codes D4 subtype of DA receptors
DRD2	11q23	40	codes D2 subtype of DA receptors
COMT	22q11.21	35	affects degradation of catecholamines (including DA)

Note. Location = chromosome location of the gene; SNPs = number of single nucleotide polymorphisms in that gene available in the SAGE data from the Illumina Human IM Bead Chip following quality control procedures; DRD3 = dopamine receptor D3; SLC6A3 = solute carrier family 6 (DAT1 = dopamine transporter 1); DRD1 = dopamine receptor D1; DDC = dopa decarboxylase; DBH = dopamine beta-hydroxylase; DRD4 = dopamine receptor D4; DRD2 = dopamine receptor D2; COMT = catechol-O-methyltransferase; L-DOPA = L-3,4-dihydroxyphenylalanine.