In another genetic analysis, VIPR2 SNPs were found to be significantly associated with depression (including bipolar disorder) (Soria et al., 2010) and hypomethylation at CpG sites of VIPR2 was observed in DNA samples derived from the saliva of children with attention-deficit/hyperactivity disorder (Wilmot et al., 2016). This evidence concerns the gene VIPR2 and bipolar disorder.