Table 2. Genotype Frequencies and Scoring for Each Polymorphism.

Polymorphism	Genotypes	n	Frequency	DA-related composite score
				Additive	Dominant
DAT1 VNTR	9/9	16	0.17	High	High
	9/10	36	0.38	Intermediate	High
	10/10	42	0.45	Low	Low
COMT rs4680	Met/met	25	0.27	High	High
	Met/val	41	0.44	Intermediate	High
	Val/val	28	0.30	Low	Low
DRD2 rs1076560	T/T	1	0.01	High	High
	T/G	27	0.29	Intermediate	High
	G/G	66	0.70	Low	Low
DRD4 VNTR	Long/long	3	0.03	High	High
	Long/short	29	0.31	Intermediate	High
	Short/short	61	0.65	Low	Low

For the DA-related genetic composite measure, two scoring models were evaluated. For the additive model, “high” genotypes (two alleles associated with higher DA tone) were scored as 2, “intermediate” genotypes as 1, and “low” genotypes as 0, and the total possible score ranged from 0 (no higher DA alleles) to 8 (all higher DA alleles). For the dominant model, homozygous “high” genotypes and heterozygous “intermediate” genotypes were each scored as 1 and “low” genotypes as 0, and the total possible score ranged from 0 (homozygous for all lower DA alleles) to 4 (homozygous or heterozygous for all higher DA alleles).