Genotypic association between dopamine transporter gene polymorphisms and schizophrenia.

Dopamine transporter (DAT) gene variants do not appear to provide widespread contributions to the etiology of schizophrenia spectrum disorders, according to linkage studies [Persico et al., 1995: Am J Psychiatry 152:134-136]. They may, however, produce modifying effects, more readily detectable in specific subpopulations of schizophrenics through associations analyses. We therefore compared polymorphic DAT gene variable number tandem repeat (VNTR) distributions in 84 controls and 147 patients, divided according to DSM-IIIR schizophrenia type criteria. No evidence of allelic association between DAT alleles and schizophrenia or any specific schizophrenia subtype was found. Interestingly, the DAT genotype distribution among schizophrenic patients did display a statistically significant departure from the genotype distribution found in controls. Such discrepancies may represent stigmata of assortative mating or may suggest a "modifying" contribution of homozygote DAT genotypes to pathogenetic processes underlying schizophrenia.