G protein beta 3 subunit gene polymorphism and left ventricular mass in young normotensives

Abstract

The 825 allele of the gene GNB3, which encodes the beta3 subunit of heterotrimeric G proteins, is associated with enhanced signal transduction via G proteins through the generation of a splice variant termed Gbeta3s. Recent studies have shown that polymorphism of GNB3 may contribute to pathogenesis of essential hypertension. To examine the association between GNB3 polymorphism and blood pressure and left ventricular mass in young normotensive subjects. The study included 159 healthy normotensive subjects from general population. In each subject, blood pressure was measured during three separate visits, 5 times on each visit. In all subjects ABPM (SpaceLabs 90207) with readings every 15 min in the day-time and every 30 min in the night-time was obtained. Mean SBP, DBP, HR and variability of blood pressure of all measurements throughout the 24-hour were calculated. Echocardiografic measurements: M-mode and 2-D were obtained (HP, Sonos 2000). The polymorphism for GNB3 gene was detected using polymerase chain reaction and restriction digestion. The genotype frequency (CC 42%, CT 52%, TT 6%) was in Hardy-Weinberg equilibrium. Age, sex and BMI as well as blood pressure values from 24-hr ABPM were similar in subjects with CC, CT and TT genotype. However, we observed higher values of left ventricular mass index in subjects with CT and TT genotypes considered together than in CC homozygous (140.69±23.2 vs 133.6±24.6 g/m2, p=0.05). Influence of GNB3 polymorphism on left ventricular mass suggests potential role of genetically fixed enhanced G-protein activation in predisposition to proliferative changes of the heart in normotensive subjects.