Association study of TPH2 polymorphisms and bipolar disorder in the Han Chinese population

• We genotyped 6 SNPs in 506 bipolar patients and 507 controls of Chinese Han origin.
• rs1386486 and rs1872824 showed marginal differences between cases and controls.
• No positive association with BPD was found for haplotypes.

ObjectiveBipolar disorder (BPD) is a serious and common mental disorder with high heritability. The serotonergic system is known to be implicated in the etiology of the disorder. Tryptophan hydroxylase isoform-2 (TPH2), which controls the synthesis of serotonin in the brain, has been suggested as a candidate gene for BDP. The aim of this study was to examine the association between the polymorphisms in TPH2 and BPD.MethodsWe conducted a case–control study by genotyping six SNPs (rs10784941, rs1386494, rs2171363, rs4760816, rs1386486, and rs1872824) in 506 bipolar patients and 507 controls of Chinese Han origin.Resultsrs10784941 was not in the Hardy–Weinberg equilibrium and therefore excluded from further analysis. rs1386486 and rs1872824 showed statistically significant differences between cases and controls in genotype frequencies (rs1386486: p = 0.043351; rs1872824: p = 0.016563), but no association in allele frequencies. Strong LD was found among rs1386494, rs2171363 and rs4760816, but no positive association with BPD was found for haplotypes.ConclusionOur results indicate that in the Han Chinese population TPH2 may be a potential susceptibility gene for bipolar disorder. Further studies are needed to validate this association.