Polymorphisms of the β 1 ( ADRB1 ) and β 2 ( ADRB2 ) adrenergic receptor genes in essential hypertension accompanying obesity

Abstract

Background The blood pressure level is determined by cardiac output and peripheral resistance both of which are regulated by the sympathetic nervous system. Presence of Ser49Gly polymorphism at beta1-adrenergic receptor gene (ADRB1) locus and Arg16Gly polymorphism at beta2-adrenergic receptor gene (ADRB2) locus are supposed to have an impact on the adrenergic receptor functional status. The aim of this study was to evaluate whether these polymorphisms are associated with the hypertension in obese individuals.
Material and methods We recruited 207 patients with essential hypertension of whom 103 were obese and 104 have a normal BMI. Genotyping of the Ser49Gly polymorphisms was underteken by PCR-RFLP, whereas the detection of Arg16Gly polymorphisms was performed by using the ARMS method. Results The allele frequency of Gly49 (38% vs. 45%, p = 0.50) and Gly49Gly homozygotes (9% vs. 13%, p = 0.50) at beta1-adrenergic receptor gene locus did not differ between obese and non-obese subjects with hypertension. The distribution of the allele Gly16 (66% vs. 53%, p = 0.005) and homozygotic genotype GG (49% vs. 29%, p = 0.014) at adrenoreceptor beta2 gene locus were significantly different in patients with BMI ≥ 30 kg/m² and hypertension compared to subjects with normal BMI and hypertension. Further statistic analysis demonstrated that the hypertensive bearers of Gly16Gly genotype are of the increased risk of obesity (OR = 2.33; 95% CI: 1.30-4.17; p = 0.0043). Additional stratification divulged that presence of Gly16 variant constitute a risk of obesity in the hypertensive female subjects younger than 60 years old (OR = 3.01; 95% CI: 1.35-6.71; p = 0.0073). Analysis of haplotypes of these two genomic loci did not indicate the synergistic action in hypertension-associated obesity.
Conclusions The carrier status of Gly16 variant od the ADRB2 gene may contribute to an increased risk of obesity in the hypertensive women younger than 60 years old.