BRIEF REPORTS 134 AmJPsychiatry 152:1,January 1995 Exclusion of Close Linkage of the Dopamine Transporter Gene With Schizophrenia Spectrum Disorders

disorders has been indicated in twin, adoption, and familial aggregation studies; the pivotal role played by the dopamine transporter in dopaminergic neurotransmission makes it a can-didate gene for these disorders. Detection of close linkage between a dopamine transporter marker and schizophrenia spectrum disorders would strongly support the existence of causal relationships between genetic mutations at the dopamine transporter locus and the disease phenotype. Method: The authors assessed the linkage between this gene and schizophrenia spectrum disorders by using polymorphic dopamine transporter gene markers in 1 56 subjects from 1 6 multiplex pedigrees with schizophrenia as well as schizophreniform, schizoaffec-tive, and schizotypal disorders and mood-incongruent psychotic depression. Results: Com-plete (9=0.0) linkage to the schizophrenia spectrum was excluded under both dominant and recessive models. Conclusions: These results indicate that allelic variants at the dopamine transporter locus do not provide major genetic contributions to the etiology of schizophrenia and related disorders in these pedigrees. (AmJ Psychiatry 1995; 152:134-136) M uch work directed toward identifying etiologi