Lack of association in Japanese patients between neuroleptic malignant syndrome and the TaqI A polymorphism of the dopamine D2 receptor gene

OBJECTIVE: The molecular basis of neuroleptic malignant syndrome (NMS) is unclear, but clinical studies have noted a genetic predisposition. A recent genetic study suggested an association between NMS and the I A polymorphism in the dopamine D2 receptor (DRD2 ) gene. We further examined the association in a larger number of subjects. METHODS: We studied 49 Japanese patients previously diagnosed with NMS, and 123 schizophrenic patients treated with neuroleptics without occurrence of NMS. PCR and RFLP analyses were performed to screen the I A polymorphism. RESULTS: The I A1 allele frequency was 0.408 in NMS patients and 0.415 in patients without NMS. No significant differences in allelic or genotypic frequencies were observed between the two groups. CONCLUSIONS: We cannot conclude that the I A polymorphism is associated with development of NMS.