Table 1

Studies of the association between attention-deficit hyperactivity disorder (ADHD) and the SLC6A3 480-bp VNTR allele

Study	Location	No. of probands	Diagnostic system	Test of association	Linkage	Statistic	p value
Barr et al27	Canada	102	DSM-IV	TDT	–	χ² = 2.6	0.06
Roman et al28	Brazil	81	DSM-IV	HHRR	–	χ² = 0.02	0.88
Curran et al29	Turkey	111	DSM-IV	TDT	–	χ² = 0.93	0.34
Curran et al29	United Kingdom	66	DSM-IV	TDT	+	χ² = 8.97	0.001
Holmes et al30	United Kingdom	137	ICD-10, DSM-IV and DSM-III-R	TDT	–	OR = 0.89	0.59
Palmer et al31	United States	209	DSM-IV and DSM-III-R	TDT	–	OR = 0.88	0.40
Daly et al32	Ireland	118	DSM-IV	HHRR	+	RR = 1.2	0.006
Waldman et al33	United States	122	DSM-IV	TDT	+^*	OR = 1.63	0.06
Cook et al34	United States	49	DSM-III-R	HHRR	+	OR = 3.17	0.01

Note: DSM = Diagnostic and Statistical Manual of Mental Disorders; TDT = transmission disequilibrium test; HHRR = haplotype-based haplotype relative risk; OR = odds ratio; ICD-10 = International Statistical Classification of Diseases and Related Health Problems, Tenth revision; RR = relative risk.
↵* For combined type only.