Role of functional dopaminergic gene polymorphisms in the etiology of idiopathic intellectual disability

► We have explored associations of six functional gene variants with IID. ► Significant risk of the DRD4 VNTR 6R allele and 6R-T haplotypes was observed. ► Preferential transmission of rs4680 “A” allele was also noticed. ► DAT1 3′UTR VNTR 9R allele and 9R-5R haplotype showed bias in transmission. ► Data obtained indicate “hypodopaminergic” status in Indo-Caucasoid IID probands.