Association of adiponectin gene polymorphism rs266729 with type two diabetes mellitus in Iraqi population. A pilot study

Background: Diabetes incidence is increasing worldwide. Many studies demonstrated that polymorphisms within the adiponectin gene could be associated with type 2 diabetes mellitus (T2DM).

Methods: A case-control study was conducted to find the association between SNP rs266729 and T2DM in Iraqi population. The study included 135 patients referring to diabetic clinic in Najaf city randomly selected based on World Health Organization (WHO) guidelines and 135 healthy controls. DNA was extracted from blood and genotyped by PCR-RFLP by using (HhaI) enzyme. Multinomial logistic regression was applied to compare the proportions of genotypes and alleles. The odds ratio for risk of developing T2DM was calculated with and without adjustment for age, sex, and BMI.

Results: The frequency of the G allele of rs266729 (C/G) polymorphism was significantly higher (p=0.00) in diabetic subjects (28%) compared to that in normal subjects (14%). The homozygous genotype (GG) significantly (OR=3.67, CI 95%(1.25-10.76), P=0.01) increased the risk of T2DM by three folds with respect to those of the wild type (CC) after adjustment for age, sex and BMI, furthermore the heterozygous CG genotype significantly (OR=2.45, CI 95%(1.41-4.26), P=0.001) raised the risk of T2DM by two folds. Homozygous and heterozygous genotypes of rs266729 polymorphism exhibited significant association with raised fasting insulin values (p=0.01), and decreased HDL levels (p=0.00).

Conclusion: Adiponectin gene polymorphism rs266729 is involved in the pathogenesis of T2DM. In addition this SNP may play a role in the development of cardiovascular diseases and metabolic syndrome by affecting HDL and insulin levels.