50-bp Ins/Del polymorphism of SOD1 is associated with increased risk of cardiovascular disease.

Compelling evidence suggests that the oxidative stress plays a key role in the pathophysiology of cardiovascular disease (CVD). Superoxide dismutase (SOD) enzymes play a major role in detoxification of reactive oxygen species and protection against oxidative stress. We examined the possible association between a 50-bp insertion/deletion in the SOD1 promoter 1684-bp upstream of the SOD1 ATG with CVD in an Iranian population. A total of 400 individuals including 200 CVD patients and 200 healthy subjects from the same ethnic background as the control group were participated in this study. Genomic DNA from all subjects was screened for the 50-bp SOD1 promoter deletion using a polymerase chain reaction (PCR) assay. Our finding showed an association between SOD1 DEL/DEL (9% vs. 2.5%) and INS/DEL genotypes and risk of CVD and these genotypes increased the susceptibility to CVD (OR=2.096, 95% CI: 1.336-3.286, P= 0.001 for the INS/DEL genotype; OR=4.811, 95% CI: 1.734-13.346, P= 0.003 for the DEL/DEL genotype). Additionally, the DEL allele of the SOD1 variation was found to be more prevalent in the CVD patients with the frequency of 26.3% and 13.5% in cases and controls, respectively, and this difference reached statistical significance (OR=2.281, 95% CI: 1.586-3.279, P= 0.001).  The analysis of SOD1 genotypes according to patients' characteristics revealed that the SOD1 Ins/del and Del/Del genotypes were more prevalent in CVD patients with a history of CVD or hypertension or DM (P<0.05), whereas the majority of Ins/Ins genotype carriers had no history of these diseases. Overall, our results demonstrated that SOD1 50-bp Del/Del and Ins/Del genotypes, as well as Del, allele, were associated with an increased risk of CVD.