Positive association between the PDLIM5 gene and bipolar disorder in the Chinese Han population

Bipolar disorder is a widespread and severe brain disorder that is strongly affected by genetic factors. The PDZ and LIM domain 5 (PDLIM5) gene encodes a protein as an Enigma homologue LIM domain protein, which has been widely reported as being expressed in various brain regions. The analysis of DNA microarrays in the frontal lobes of patients with bipolar disorder has indicated changes in the expression level of PDLIM5, and subsequent studies have suggested that PDLIM5 might play a role in susceptibility to bipolar disorder. We sought to examine the association between PDLIM5 and bipolar disorder.

We recruited 502 patients with bipolar disorder and 507 controls from Anhui Province, China. We conducted a case-control study of 4 single-nucleotide polymorphisms (SNPs) of PDLIM5 that have been reported to be significantly associated with bipolar disorder in the Japanese and Chinese population: rs10008257, rs2433320, rs2433322 and rs2438146.

We found that rs2433322 showed significantly different frequencies between patients and controls (p = 0.002). Three of the SNPs, rs10008257, rs2433320 and rs2438146, showed no statistical association with bipolar disorder; however, haplotypes constructed from 3 SNPs, rs2433320, rs2433322 and rs2438146, were significantly associated with bipolar disorder (global p = 0.004 after Bonferroni correction).

Our genetic association study only offered evidence for susceptibility of PDLIM5 to bipolar disorder, but the positive SNP rs2433322 could not indicate a direct cause of this complicated brain disorder. In addition, the 4 tagged SNPs that we selected could not cover the whole region of PDLIM5, thus additional reproducible studies of more SNPS in large non-Asian populations are needed.

Our results suggest that PDLIM5 might play a role in susceptibility to bipolar disorder among the Chinese Han population.