Polymorphic variations in manganese superoxide dismutase (MnSOD), glutathione peroxidase-1 (GPX1), and catalase (CAT) contribute to elevated plasma triglyceride levels in Chinese patients with type 2 diabetes or diabetic cardiovascular disease

Manganese superoxide dismutase (MnSOD), glutathione peroxidase-1 (GPX1), and catalase (CAT) provide the primary antioxidant defense system. Impaired antioxidant defense increases oxidative stress and contributes to the development of type 2 diabetes and diabetic cardiovascular disease (CVD). We preformed a case-control study in Chinese type 2 diabetes patients, to determine if the MnSOD Val16Ala (T -> C), GPX1 Pro198Leu (C -> T), and CAT -262C/T (C -> T) functional polymorphisms contribute to the development of type 2 diabetes or diabetic CVD. Patients with type 2 diabetes (n = 168) were divided into the non-CVD group (n = 83, > 10 year since diagnosis) and CVD group (n = 85, history of ischemic CVD). Genotyping was performed using PCR-restriction fragment length polymorphism (PCR-RFLP) or PCR-based direct sequencing. The genotypic distribution in the non-CVD- and CVD-group and the clinical parameters in genotypic groups were not significantly different in the three polymorphic sites, respectively. Among eight genotypic combinations, the most common TT+CC+CC genotype (59.5%) was associated with higher triglyceride levels than the TT+CT+CC genotype, the second frequent one (14.9%; 1.77 +/- A 0.12 vs. 1.21 +/- A 0.11 mmol/l, P = 0.001), and all non-TT+CC+CC genotypes (40.5%; 1.77 +/- A 0.12 vs. 1.43 +/- A 0.12 mmol/l, P = 0.048). In the CVD group, significantly elevated triglyceride levels were also observed in patients with TT+CC+CC compared to patients with TT+CT+CC (2.00 +/- A 0.18 vs. 1.37 +/- A 0.16 mmol/l, P = 0.018) or non-TT+CC+CC genotypes (2.00 +/- A 0.18 vs. 1.65 +/- A 0.19 mmol/l, P = 0.070). The common MnSOD, GPX1, and CAT TT+CC+CC genotype may contribute to hypertriglyceridemia in Chinese patients with type 2 diabetes or diabetic CVD.