Homozygosity for the Gly-9 variant of the dopamine D3 receptor and risk for tardive dyskinesia in schizophrenic patients
This study was undertaken to re-examine whether homozygosity for the Gly-9 variant (allele 2) of the dopamine D3 receptor gene (DRD3) is associated with increased risk for tardive dyskinesia (TD) in schizophrenic patients. Seventy-one antipsychotic-treated subjects with schizophrenia from Newcastle upon Tyne, UK, were genotyped for the presence of allele 1 (Ser-9) and allele 2 (Gly-9) of the dopamine D3 receptor (DRD3) Ser-9-Gly polymorphism. Among 32 patients with TD, 7 subjects (22 %) were homozygous for the Gly-9 variant (2–2 genotype), whereas 4 out of 39 patients (10 %) without TD had this genotype. The non-significant tendency in this sample towards an over-representation of allele 2 and the 2–2 genotype among schizophrenic patients with TD is in line with our initial report as well as recent studies by others, indicating that the Gly-9 allele of DRD3 may be a susceptibility factor for the development of TD in neuroleptic-treated individuals with schizophrenia. There are, however, some recent non-supportive reports, and since the trend in our present study failed to reach statistical significance, further studies on larger samples and future meta-analysis may be necessary to establish the role of the DRD3 in the pathogenesis of TD.(Received July 18 1999)
(Reviewed October 10 1999)
(Revised December 5 1999)
(Accepted December 20 1999)
Key Words: Dopamine; DRD3; schizophrenia; tardive dyskinesia.
c1 Address for correspondence: Dr R. Løvlie, Dr Einar Martens' Research Group for Biological Psychiatry, Centre for Molecular Medicine, University of Bergen, Haukeland University Hospital, N-5021 Bergen, Norway. Tel.: +47 55 97 54 25 Fax: +47 55 97 51 41 E-mail: firstname.lastname@example.org