Insulin receptor substrate gene polymorphisms are associated with metabolic syndrome but not with its components

Aim: Metabolic syndrome (MetS) is a major risk factor for both diabetes mellitus and cardiovascular disease (CVD). The aims of the study were 1) to investigate the insulin receptor substrate-1 (IRS-1) and insulin receptor substrate-2 (IRS-2) gene polymorphisms in patients with MetS and 2) to examine the relationships between gene polymorphisms and components of MetS. Patients & Methods: The study population included 100 patients with MetS and 30 patients without MetS as control group. Metabolic syndrome (MS) was defined as in ATP III. Entire coding exons of IRS-1 and IRS-2 genes were amplified by polymerase chain reaction (PCR). Insulin resistance (IR) was estimated using the homeostasis model assessment (HOMA). Results: In patients with MetS, 34 (34%), had G972R (rs1801278) gene polymorphism and 66 (66%) had no nucleotide substitutions at the IRS-1 gene (p < 0.0001). As for the IRS-2 gene, 18.0% of the patients were heterozygous and 11.0% were homozygous for the G1057D mutation, 2.0% were heterozygous for the P1031P and P1033PG1057 mutations, 17.0% were heterozygous for P1033P, 3.0% were homozygous for P1033P and 5% were heterozygous for the G 1067D and P1033P mutations in patients with MetS (p = 0.0001). However, none of the control subjects had nucleotide substitutions in the IRS-1 and IRS-2 genes. There were no correlations between IRS-1/IRS-2 gene polymorphisms and metabolic syndrome components such as waist circumference, blood pressure, triglyceride, HDL-Cholesterol, LDL-Cholesterol and HOMA-IR levels. Conclusion: Insulin receptor substrate-1 and 2 gene polymorphisms were associated with metabolic syndrome but not its components.