Previously, we found that the iSNP of the ST8SIA2 gene, which has been reported to be associated with bipolar disorder, results in an increase in mRNA of the ST8SIA2 gene, ST8SIA2 and their product, and polySia-NCAM as compared with controls; however, the cell surface expression of polySia was not significantly changed [47]. This evidence concerns the gene NCAM1 and bipolar disorder.