PMP22 and schizophrenia: In addition, 20 of our brain MA genes, including autism risk genes (e.g., ANK2, NF1) and schizophrenia risk genes (e.g., APC, EGR1, FGFR3, PMP22, TCF4, TFRC, and YWHAE), were also included in the database of human haploinsufficient genes [47] (Fisher’s exact test, p = 0.54; Additional file 2: Table S4), suggesting that some of our MA genes may be quite susceptible to damaging mutations that could lead to a loss of gene expression in subsets of brain cells.