Systematic Review of Methylenetetrahydrofolate Reductase (MTHFR) 677C>T and 1298A>C Variants and Treatment-Resistant Depression: Insights for Precision Psychiatry

While evidence suggests a role for <i>MTHFR</i> variants in TRD, heterogeneity among studies limits definitive conclusions. Future research should standardize TRD definitions, control for confounding factors, and explore the integration of genetic testing into clinical practice. L-methylfolate supplementation may represent a promising adjunctive strategy for MDD patients carrying <i>MTHFR</i> risk variants.