GPR88 and bipolar disorder: Investigation of the transcriptional effects of rs79229764 variant in post-mortem brain data of schizophrenia patients suggested upregulation of GRP88 and PUDP, and downregulation of JMJD7. Of particular interest may be the GPR88 gene, which encodes an orphan G-protein coupled receptor of the class A rhodopsin family (GPR88) that has previously been suggested to be a candidate susceptibility gene for sporadic cases of schizophrenia and bipolar disorder [38, 39].