MTHFR and type 2 diabetes mellitus: Therefore, this study was designed to investigate the association of polymorphisms in the genes GSTM1 (gene deletion), GSTT1 (gene deletion), GSTP1 (rs1695), ACE (rs4646994), ACE2 (rs2285666), VEGF-A (rs28357093), and MTHFR (rs1801133) and their combined effects on the development of T2DM in the population of Goiás, Brazil.