Nominal association between a polymorphism in DGKH and bipolar disorder detected in a meta-analysis of East Asian case-control samples

Aim: Recent genome-wide association studies (GWAS) of bipolar disorder (BD) have detected new candidate genes, including DGKH, DFNB31 and SORCS2. However, the results of these GWAS were not necessarily consistent, indicating the importance of replication studies. In this study, we tested the genetic association of DGKH, DFNB31 and SORCS2 with BD. Methods: We genotyped 18 single-nucleotide polymorphisms (SNP) in DGKH, DFNB31 and SORCS2 using Japanese samples (366 cases and 370 controls). We also performed a meta-analysis of four SNP in DGKH, using the previously published allele frequency data of Han-Chinese case-control samples (1139 cases and 1138 controls). Results: In the association analysis using Japanese samples, a SNP in SORCS2 (rs10937823) showed nominal genotypic association. However, we could not find any association in an additional analysis of tag SNP around rs10937823. In the meta-analysis of SNP in DGKH, rs9315897, which was not significantly associated with BD in the previous Chinese study, showed nominal association. Conclusion: Although the association was not strong, the result of this study would support the association between DGKH and BD.