TCF4 and schizophrenia: The number of Chinese individuals was 1034 cases and 1034 normal controls.6 In 2009, three GWAS studies from the ISC, SGENE, and MGS consortia individually implicated the major histocompatibility complex (MHC) region located on chromosome 6p22.1, transcription factor 4 (TCF4) and neurogranin (NRGN) as key susceptible genes for schizophrenia at significant levels of P < 5 × 10−8.