Background: Protein tyrosine phosphatase 1B (PTP1B), encoded by the PTPN1 gene, efficiently dephosphorylates the insulin receptor, and attenuates insulin signaling. Recently, a 1484insG variant of the PTPN1 gene has been associated with an increased risk of metabolic syndrome in an Italian population that has not been confirmed in the subsequent studies. The purpose of this study was to investigate the association of 1484insG polymorphism of the PTPN1 with obesity, insulin resistance, type 2 diabetes and other cardiovascular-related traits in an Iranian population.
Methods: The genotypes of 1484insG variant were determined by PCR-RFLP method in 696 unrelated subjects including 412 subjects with normal glucose tolerance and normal fasting glucose and 284 type 2 diabetic patients.
Results: The allelic frequency of 1484insG polymorphism among type 2 diabetic patients and non-diabetic subjects was 4.9 and 4.1%, respectively (p = 0.475). In type 2 diabetic patients, among quantitative traits, no significant difference in anthropometric and biochemical parameters was seen between the wild-type and heterozygous 1484insG genotypes in male and female groups and in non-diabetic subjects, male carriers of 1484insG allele had significantly higher fasting insulin (p = 0.003), cholesterol (p = 0.012), LDL-C (p = 0.037), apo B (p = 0.015), and HOMA-IR (p = 0.011) levels compared to the individuals carrying the wild-type genotype. Among non-diabetic female individuals, only body mass index was significantly higher in 1484insG subjects compared to the wild-type individuals (p = 0.007).
Conclusions: Our results from a sample of Iranian type 2 diabetes cases and controls provide evidence that the 1484insG genotype of the PTPN1 gene may be associated with insulin resistance and other cardiovascular risk factors in non-diabetic male subjects.