Genetic polymorphisms of beta(2)- and beta(3)- adrenergic receptor genes associated with characteristics of the metabolic syndrome in black South African women

Abstract

Background: Genetic variation in the β2 (ADRB2) and β3 (ADRB3) adrenergic receptor genes are associated with obesity and insulin resistance. To further elucidate the role of these genes in the pathophysiology of obesity the present study investigated associations between certain polymorphisms in ADRB2 and ADRB3 and parameters of carbohydrate and lipid metabolism in a population of African origin. Material and Methods: Data of 102 black South African women obtained in the POWIRS (Profile of Obese Women with the Insulin Resistance Syndrome) study were used. Endpoint measurements included several anthropometric variables, resting blood pressure, plasma glucose, insulin, free fatty acids (FFA), ghrelin, leptin and lipids, and insulin resistance as estimated by the homeostasis model assessment (HOMA-IR) index. Polymorphisms were analyzed via PCR based methods. Results: The percentage body fat was significantly lower (p≤0.05) and the FFA significantly higher (p≤0.05) in lean subjects (BMI≤25 kg/m2) with the Glu27 variant allele compared to subjects with the Gln27 wildtype allele of the ADRB2 gene. In contrast, the variant allele of the ADRB2 gene was significantly positive associated (p≤0.05) with the HOMA-IR-index in overweight black African women (BMI>25 kg/m2). No significant differences in parameters of the metabolic syndrome were apparent between subjects with the wildtype and variant alleles in the ADRB3 gene. Conclusion: The presence of the Glu27 and Arg64 polymorphisms of the ADRB2 and ADRB3 genes are not directly related to indices of the metabolic syndrome