The G1057D polymorphism of IRS-2 gene is not associated with type 2 diabetes and obese patients among ethnic groups in Tunisian population.

Background: Type 2 of diabetes is the most common metabolic disorder and results from the interaction between genetic and environmental factors. Insulin receptor substrate-2 (IRS-2), one of the major substrates of the insulin receptor, has a crucial role in insulin signalling and in beta cell development and survival. While several polymorphisms have been identified in the IRS-2 gene, the association of the Gly1057Asp polymorphism with type 2 diabetes has been studied in European and Chinese populations, but the results have been inconsistent.

Objectives: The aim of this study was to investigate the association of Gly1057Asp polymorphism in insulin receptor substrate-2 (IRS-2) gene among patients with type 2 diabetes in well defined ethnic groups from Djerba Island in Southeastern Tunisia.

Methods: The studied population (172 Arabs and 100 Berbers) includes 162 patients with type 2 diabetes and 110 healthy controls. BMI was calculated for each subject. The subjects were unrelated and randomly selected Arabs and Berbers were equally distributed between controls and diabetics. The G1057D polymorphism of the IRS-2 gene was genotyped using PCR-RFLP assay.

Results: This case/control study indicated that frequency of the IRS-2 Gly1057Asp polymorphism was not significantly different between the healthy controls and type 2 diabetic groups, neither between healthy nor obese subjects, in both ethnic groups. Moreover, this polymorphism is present at a lower frequency in Djerbian than in neighbouring European populations.

Conclusion: These results strongly argue against a major role of the Gly1057Asp IRS-2 polymorphism in the pathogenesis of type 2 diabetes in Djerbian subjects.