Effects of the C825T polymorphism of the GNB3 gene on body adiposity and blood pressure in fertile and menopausal women:: a population-based study

Objectives The 825T allele of the GNB3 gene is implicated in adipose distribution, predisposing to obesity and hypertension. Menopause is also considered a condition leading to excess adiposity and hypertension. The aim of the present study was to clarify whether the effects of menopause on body weight and blood pressure are influenced by the C825T polymorphism of the GNB3 gene. Methods The study involved 1339 subjects (43% men) aged 18-95 years, genotyped at the GNB3 825 locus, undergoing, in an epidemiological population-based frame, questionnaire, anthropometrics and blood examinations. Results Mean skinfold thickness (MST), truncal obesity and excess subcutaneous adiposity ( MST greater than median) were higher in women than in men. A significant interaction was detected between menopausal status and the C825T polymorphism (P-int > 0.0001). MST, truncal obesity and excess subcutaneous adiposity were lower in CC fertile than menopausal women, but were comparable in TT fertile and menopausal women. In a multivariate logistic model for excess subcutaneous adiposity, the relative risk of menopause was 4.12 (95% confidence interval 2.35-7.22) in CC women but was insignificant in the other two genotypes. In fertile women only, higher systolic blood pressure (SBP) was detected in TT than in CC genotypes. Conclusion An interaction exists between the C825T polymorphism and menopause in controlling body adiposity and blood pressure in women. Adiposity and SBP are higher in menopausal than in fertile women, provided they have the CC genotype. TT fertile women show the same adiposity as those in menopause. Men have the same excess adiposity as menopausal women, independent of the GNB3 genotype.