Interaction of iNOS Gene (C150T) Polymorphism and Endothelial Dysfunction in Pathophysiology of Metabolic Syndrome.

OBJECTIVE: To study the endothelial dysfunction by measuring Nitric Oxide and Endothelin-1, and inter-genotypic variation of inducible Nitric Oxide Synthase gene (C150T) polymorphism among the study subjects.

METHODS: 50 diagnosed cases of metabolic syndrome as per International Diabetes Federation (IDF) criteria and 50 healthy volunteers as control were enrolled. Nitric Oxide, Endothelin were measured and PCR-RFLP was done to identify the iNOS gene C150T polymorphism and its effect on serum nitric oxide levels.

RESULTS: Subjects with metabolic syndrome had lower NO levels (16.3 ± 10.3 vs 20.9 ± 11 µM, p = 0.032) and higher endothelin (2.68 ± 1.73 vs 1.98 ± 0.82 fmol/ml, p = 0.011). The frequency of mutant T allele (10% vs 9%) was higher in cases. Serum nitric oxide levels were lower in cases expressing the Mutant T allele as compared to wild type C allele. However, the differences were not statistically significant.

CONCLUSIONS: The present study demonstrated that iNOS C150T polymorphism did not show significant association with metabolic syndrome. Serum nitric oxide levels could be influenced by factors other than genetic polymorphism of iNOS gene (C150T) which cause endothelial dysfunction in metabolic syndrome and associated co-morbidities.