A previous meta-analysis reported a weak correlation between MTHFR C677T polymorphism, depression, and anxiety in children and adults by studying 1,119 cases of schizophrenia and 1,308 controls reporting that 677TT genotype had the greatest risk of schizophrenia (OR = 1.48; CI 95%, 1.18–1.86), compared to subjects with CC and CT genotype combined [78]. This evidence concerns the gene MTHFR and major depressive disorder.