HTR4 and schizophrenia: The 3rd and 4th genes in that category were genes coding for serotonin receptors HTR2A and HTR4. Finally, some of the top ranked genes are related to brain-related disorders: G-protein signaling regulator RGS4, serotonin receptor HTR2A and the postsynaptic protein encoder–NRGN are related to schizophrenia.