However, there were no significant differences in the mRNA expression levels of HTR1A (p = 0.17), HTR2A (p = 0.09), HTR6 (p = 1.0), and HTR7 (p = 0.476) (Additional file 1: Fig. S2B–E) between schizophrenia patients and healthy controls. Here, HTR6 is linked to schizophrenia.