Association of G22A polymorphism of the adenosine deaminase (ADA) gene with biochemical characteristics in type 2 diabetic Palestinians
The adenosine deaminase G22A polymorphism (20q.11.33) affects the level of adenosine deaminase (ADA) expression, which plays an important role in the regulation of intracellular and extracellular concentrations of adenosine. Recent studies reported greater ADA activity in diabetic patients and showed the role of ADA in the modulation of insulin activity and glucose homeostasis. We investigated whether the G22A polymorphism of the ADA gene is associated with type 2 diabetes mellitus (T2DM) in the Palestinian population and assessed the relationship between the G22A variant and fasting plasma glucose (FPG), glycated hemoglobin (HbA1c) and lipid profile among T2DM patients. A total of 231 individuals with T2DM and a control sample of 101 non-diabetic participants were randomly selected from those who were attending United Nations Relief and Works Agency (UNRWA) clinics for treatment and/or follow up. Genomic DNA was extracted from peripheral blood samples and PCR-RFLP was performed to identify the TaqI polymorphism G22A of the ADA gene. No significant differences were observed in the genotype and allele frequencies between T2DM patients and the control group. Yet, among diabetic patients, the GG genotype was significantly associated with higher FPG and HbA1c when compared to the GA+AA genotype but had no influence on blood pressure, BMI or other metabolic parameters. In conclusion, we confirm that the GG genotype of the ADA gene is associated with poor glycemic control in T2DM Palestinians and points to the association of the G22A variant with decreased activity of the ADA enzyme, which is of paramount importance in the pathophysiology of T2DM.