Lack of association between VNTR polymorphism of DAT gene and schizophrenia

The substantial importance of genetic factors in the etiology of schizophrenia was demonstrated in many studies. The complex model of disease inheritance seems to be the most probable, involving epistatic interaction of many genes. Association studies are based on the analysis of the so-called candidate genes, which are coding for neurotransmitter receptors, neurotransmitter transporters and enzymes involved in their metabolism. In the present work the results of an association study of VNTR polymorphism of dopamine transporter gene (DAT) in schizophrenia are presented. This polymorphism is characterised by a different number of tandem repeats (VNTR) within the 3'-untranslated region of gene. In Caucasians the 40 base pair motif has 3 to 11 repeats, the most common (about 90%) are alleles containing 9 and 10 repeats. In the present study no association between the polymorphism studied and schizophrenia was found.