The International Journal of Neuropsychopharmacology



Brief Report

Homozygosity for the Gly-9 variant of the dopamine D3 receptor and risk for tardive dyskinesia in schizophrenic patients


Roger Løvlie a1c1, Ann K. Daly a2, Richard Blennerhassett a3, Nicol Ferrier a3 and Vidar M. Steen a1
a1 Dr Einar Martens' Research Group for Biological Psychiatry, Centre for Molecular Medicine, University of Bergen, Haukeland University Hospital, N-5021 Bergen, Norway
a2 Department of Pharmacological Sciences, University of Newcastle upon Tyne, UK
a3 Department of Psychiatry, University of Newcastle upon Tyne, UK

Abstract

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.

Correspondence:
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: rlov@haukeland.no