Lack of association between polymorphism in the beta2-adrenergic receptor gene, hypertension, and obesity in the Olivetti heart study

Objective: Several case-control studies have explored the possible association between polymorphism in the beta2 adrenoreceptor gene (beta2AR), hypertension, and obesity--the focus being in particular on the Arg16Gly and Gln27Glu substitutions, which appear to modify the extracellular part of the beta2AR with possible functional modification. However, controversial results have been obtained.

Design and methods: The analysis refers to 993 middle-age men characterized for Arg16Gly and Gln27Glu polymorphism of the beta2AR. In this general population sample there were 563 overweight, 160 obese, and 405 hypertensive individuals, of whom 171 were receiving antihypertensive therapy.

Results: The genotype frequencies for codon 16 were: GlyGly = 38%; ArGly = 45%; ArgArg = 17%. The frequencies for codon 27 were: GlnGln = 50%; GlnGlu = 39%; GluGlu = 11%. Codon 16 and codon 27 polymorphisms were in linkage disequilibrium. No differences were detected in body mass index and blood pressure across different genotypes. Likewise, no association was detected between either of the two polymorphisms and being overweight (codon 27: chi2 = 0.1, codon 16: chi2 = 1.4), obesity (codon 27: chi2 = 0.1, codon 16: chi2 = 1.7) and hypertension (codon 27: chi2 = 2.7, codon 16: chi2 = 1.9). The odds ratio (with 95% confidence intervals) for overweight, obesity, and hypertension were not different between genotypes. Likewise, no difference in the anthropometric indices of fat distribution, fasting blood glucose, serum insulin, triglycerides, uric acid, and HOMA index could be detected between groups.

Conclusions: In summary, in this large unselected sample of adult white men, genetic variation in the beta2AR was not associated with blood pressure or with overweight, obesity, and fat distribution.