Genetic association study of CSNK1E gene in bipolar disorder and circadian characteristics.

BACKGROUND: A circadian rhythm disturbance is one of the essential components of the phenotype of bipolar disorder. It has been reported that casein kinase 1 epsilon (CSNK1E), a member of the clock gene family, is associated with psychiatric phenotypes.

OBJECTIVES: We performed a genetic association study to determine the genetic role of CSNK1E in bipolar disorder and circadian rhythm disturbances in the Korean population.

METHODS: The present study included 215 patients with bipolar disorder and 773 controls. Circadian characteristics were measured by the Korean version of the Composite Scale of Morningness (CS). Single-nucleotide polymorphisms (SNPs) of CSNK1E, rs1534891 and rs2075984, were genotyped. Chi-square analyses were performed to evaluate associations involving alleles and genotypes. Haplotype analysis was also performed, and the permutation p value was calculated. We also tested further associations involving these SNPs and scores on the CS.

RESULTS: We found a positive association between SNP rs2075984 and bipolar disorder in both the allelic (p = .003) and genotypic (p = .006) distributions. No allelic or genotypic association between SNP rs1534891 and bipolar disorder was observed. A significant association of haplotype with bipolar disorder was found (p = .033). However, no association between the CS and the genotype of either SNP was found in the total sample.

CONCLUSION: CSNK1E SNP rs2075984 seemed to play a significant role in the development of bipolar disorder in this Korean sample. This association does not seem to relate to the phase preference measured by the CS. Further studies on CSNK1E with larger samples and more SNPs are necessary.