The diacylglycerol kinase eta gene and bipolar disorder: a replication study in a Sardinian sample

Diacylglycerol kinase eta(DGKH) is a key enzyme involved in the regulation of the phosphatidyl inositol pathway. DGKH is located in 13q14, a region in linkage with bipolar disorder (BD). A genomewide association study (GWAS) reported a strong association between three single nucleotide polymorphisms (SNPs) located in the first intron of DGKH and bipolar disorder I (BDI) in two independent samples. In the attempt to replicate previous findings, we carried out an association study among the three DGKH SNPs and BD in our Sardinian sample of bipolar I patients. Moreover, as a group of patients was characterized for the response to lithium prophylaxis, we tested whether DGKH variants were involved in lithium response. In conclusion, the association for a DGKH haplotype reported in our sample, although intriguing, must be interpreted with caution and further studies need to be performed to clarify the role of DGKH in BD. Finally, the lack of association with the lithium response is far from being considered conclusive.