Apolipoprotein E epsilon 4 and tardive dyskinesia in a Japanese population

The findings that free radicals play a causative role in the occurrence of tardive dyskinesia (TD) and that apolipoprotein E (ApoE) 4 has decreased an ti-oxidant activity suggest a potential link between TD and ApoE alleles. W e, therefore, examined ApoE allelic frequencies in schizophrenic subjects w ith TD and non-TD. Serum samples were obtained from 333 DSM IV-diagnosed sc hizophrenic patients and 191 controls in Japan. The presence of TD was eval uated by research diagnostic criteria for TD. ApoE phenotypes of the serum samples were determined by polyacrylamide gel isoelectricfocusing. A total of 62 TD subjects (31 males, 31 females) were identified among all patients examined. No significant differences in ApoE allelic frequency were found between TD and non-TD groups. ApoE epsilon4 allele frequency, however, was significantly lower in the female TD group than in the male TD group. These findings do not clearly demonstrate a certain association between TD and t he epsilon4 allele, but may preliminarily reveal a difference in influence of this allele on the development of TD between males and females. (C) 2000 Elsevier Science Ltd. All rights reserved.