Dopaminergic gene polymorphisms and cognitive function in a north Indian schizophrenia cohort

Abstract Background Associations of polymorphisms from dopaminergic neurotransmitter pathway genes have mostly been reported in Caucasian ancestry schizophrenia (SZ) samples. As studies investigating single SNPs with SZ have been inconsistent, more detailed analyses utilizing multiple SNPs with the diagnostic phenotype as well as cognitive function may be more informative. Therefore, these analyses were conducted in a north Indian sample. Methods Indian SZ case-parent trios ( n = 601 families); unscreened controls ( n = 468) and an independent set of 118 trio families were analyzed. Representative SNPs in the Dopamine D3 receptor ( DRD3 ), dopamine transporter ( SLC6A3 ), vesicular monoamine transporter 2 ( SLC18A2 ), catechol-o-methyltransferase ( COMT ) and dopamine beta-hydroxylase ( DBH ) were genotyped using SNaPshot/SNPlex assays ( n = 59 SNPs). The Trail Making Test (TMT) was administered to a subset of the sample ( n = 260 cases and n = 302 parents). Results Eight SNPs were nominally associated with SZ in either case-control or family based analyses ( p