ADRB2 gene variants, dual-energy x-ray absorptiometry body composition, and hypertension in Tobago men of African descent

Abstract 

Classic tissue effects of β₂-adrenergic receptor activation include skeletal muscle glycogenolysis and vascular smooth muscle relaxation, factors relevant to obesity and hypertension, respectively. In a population-based study, we examined 2 common amino acid substitutions in the β₂-adrenergic receptor gene (ADRB2) in relation to body composition and blood pressure. A cross-sectional analysis of 1893 African-descent men living in Tobago and participating in a prostate cancer screening study was performed. Body mass index, waist circumference, blood pressure, dual-energy x-ray absorptiometry body composition, and ADRB2 (Arg16Gly; Gln27Glu) genotype were determined. Twenty-six percent were obese (body mass index ≥30 kg/m²), and 50% were hypertensive. ADRB2 Arg16Gly and Gln27Glu alleles were in linkage disequilibrium (D′ = 0.96, r² = 0.15). ADRB2 16Gly-containing and 27Glu-containing genotypes were equally frequent in low, medium, and high tertiles of percentage of body fat mass (16Gly-containing genotypes: 73.4%, 74.4%, and 74.5%, P_trend = .66; 27Glu-containing genotypes: 27.6%, 23.8%, and 25.4%, P_trend = .39) and in normal blood pressure, prehypertensive, and hypertensive men (16Gly-containing genotypes: 73.4%, 72.8%, and 74.4%, P_trend = .61; 27Glu-containing genotypes: 25.6%, 24.1%, and 26.7%, P_trend = .50). In a high-obesity and high–hypertension risk population with ancestry in common with African Americans, genetic variation defined by 2 common ADRB2 amino acid substitutions was not associated with body composition or hypertension.