No evidence for linkage or association between the dopamine transporter gene and schizophrenia in a French population.

Pharmacological and clinical findings suggest that the dopamine transporter (DAT) gene may be involved in the genetic predisposition to schizophrenia. Linkage of a Taq I VNTR polymorphism in the DAT gene to schizophrenia was studied in multiplex schizophrenic families from Rouen, France (n = 10) and the Island of La Réunion (n = 21). Neither the lod score method nor nonparametric methods (the affected pedigree member method of Weeks and Lange [1988] and the sibling method of Green and Woodrow [1977]) provided any evidence for linkage. An association study, carried out within a group of 91 unrelated schizophrenic patients from Rouen and 91 matched control subjects, examined a 40 base-pair repeat polymorphism located in the 3' nontranslated end of the DAT mRNA. There was no significant difference in allelic or genotypic frequencies between the two groups. These results exclude any substantial involvement of the DAT gene in the pathogenesis of schizophrenia in the population studied.