MTHFR and schizophrenia: It has been reported that the polymorphisms of MTHFR were associated with the metabolic syndrome in both the general population (10–14) and antipsychotic-administrated schizophrenia patients (15, 16), which makes the genetic variant of MTHFR a potential predictor for antipsychotic-induced metabolic side effects (e.g., weight gain) (15–17).