No association of the dopamine transporter gene 3 ' VNTR polymorphism withADHD subtypes in a population sample of twins

Dopamine pathway genes have been the subject of a variety of studies testin g the association of candidate genes and liability for attention-deficit hy peractivity disorder (ADHD). Due to the known effects of stimulant medicati ons such as methylphenidate on the dopamine transporter, a variety of case control and family-based transmission distortion genetic studies of ADHD ha ve focused on DAT1 polymorphisms. The most widely reported positive finding has been with a variable number of tandem repeats (VNTR) polymorphism of u nknown function in the 3' untranslated region of the DAT1 gene. In this rep ort, we test for association of alleles of this polymorphism. with ADHD usi ng population-derived samples of twins. We use the transmission disequilibr ium test and ADHD subtypes defined by both DSM-IV and latent class criteria . We fail to demonstrate any significant association or trend for associati on of any of the VNTR alleles with any of the variously defined ADHD subtyp es. (C) 2001 Wiley-Liss, Inc.