TCF4 and schizophrenia: Large genome-wide association studies (GWAS) with some replicable and intriguing findings have suggested that several single nucleotide polymorphisms (SNPs) of TCF4 are consistent with and significantly increase susceptibility to schizophrenia (Schizophrenia Psychiatric Genome-Wide Association Study [GWAS] Consortium, 2011; Steinberg et al., 2011; Zammit et al., 2014).