SOD2 and type 2 diabetes mellitus: All four genes carnosinase (CNDP1-D18S880 and -rs2346061), endothelial nitric oxide synthase (NOS3-rs1799983), and manganese superoxide dismutase (MnSOD-rs4880) with oxidative stress-related polymorphisms have significant effects on the development of nephropathy in Malaysian type 2 diabetes patients.