DRD4 Gene Polymorphisms as a Risk Factor for Children with Attention Deficit Hyperactivity Disorder in Iranian Population

Table 3

Frequency of variable number of tandem repeats (VNTR) in exon 3 of the DRD4 gene in Iranian children.

Number of repeats	ADHD group		Control group		value
	Number	Percentage	Number	Percentage
2R	3	2.3	9	6.9	>0.05
3R	4	3.1	16	12.3	>0.05
4R	99	76.2	70	53.8	0.004
5R	9	6.9	12	9.2	>0.05
6R	8	6.2	11	8.5	>0.05
7R	7	5.4	12	9.2	>0.05