Genetic variation in folylpolyglutamate synthase and gamma-glutamyl hydrolase and plasma homocysteine levels in the Singapore Chinese Health Study

► We examine the impact of SNPs in FPGS and GGH genes on homocysteine levels. ► Three GGH SNPs may influence homocysteine levels. ► Functional changes have implications for cardiovascular disease and cancer research. ► Functional changes have implications for methotrexate treatment response.