Lack of association between schizophrenia and polymorphisms in dopamine metabolism and transport genes.

We investigated the relationship between several functional polymorphisms in genes coding for dopamine metabolism and transport enzymes (MAO-A VNTR; MAO-A 941T>G; DAT VNTR; DAT -67A/T; CYP2D6*3; CYP2D6*4; CYP2D6*5; CYP2D6*6) and the frequency of schizophrenia. Participants in the study were 242 subjects diagnosed with schizophrenia and related disorders and 290 hospital-based controls. Genomic DNA was isolated from whole blood and genotyped by several methods. However, there was no association between schizophrenia and the alleles, genotypes or diplotypes that were studied or their interactions. Polymorphisms in genes coding for dopamine metabolism and transport enzymes did not predispose to or protect from schizophrenia and related disorders.