Monocyte chemoattractant protein-1 promoter -2518 polymorphism may have an influence on clinical heterogeneity of bipolar I disorder in the Korean population.

The aim of this study was to investigate the association between monocyte chemoattractant protein-1 (MCP1) promoter -2518 polymorphism and DSM-IV-based bipolar I disorder (BID) in Korea. Ninety-two patients with BID and 114 healthy controls participated in this study. A polymerase chain reaction-based method was used for genotyping. Genotype and allele distributions in patients with BID were not different from those of the controls, nor were they different according to clinical factors in the patient group. However, the frequency of the A allele (p = 0.028) was significantly different when subdividing the patient group into patients with manic episode versus depressed and mixed episode. The present study suggests that the MCP1 promoter -2518 polymorphism may not confer susceptibility to BID itself, but could have an influence on the clinical heterogeneity of BID, at least in the Korean population.