MTHFR and schizophrenia: Moreover, meta-analyses studies conducted by Lewis et al. [38], Muntjewerff et al. [39], Gilbody et al. [31], Yoshimi et al. [40], and Peerbooms et al. [34], tested for an association between MTHFR C677T and schizophrenia, reported an increased risk of schizophrenia with the TT genotype and the carriers of the T allele.