G protein beta3 subunit gene 825T allele is associated with increased left ventricular mass in young subjects with mild hypertension.
BACKGROUND
A nucleotide substitution (C-->T) at position 825 of the gene GNB3 encoding the beta3 subunit of heterotrimeric G proteins is associated with alternative splicing and enhanced signal transduction. There is accumulating evidence from different populations that the 825T allele is associated with increased prevalence of hypertension, obesity, and left ventricular hypertrophy. However, it is unclear to what extent the 825T allele has a direct influence on left ventricular structure, independently of the effects of pressure and body mass index. Therefore we explored whether the GNB3 825T allele is associated with increased left ventricular mass index in a selected and homogeneous group of young, never treated, mild hypertensives.


METHODS
Young subjects (n = 207, aged 18 to 45 years) were genotyped at the GNB3 825 locus. In each patient, 24-h ambulatory blood pressure (BP) measurement and two-dimensional guided M-mode echocardiography combined with Doppler sonography were performed.


RESULTS
The genotype distribution among patients was in Hardy-Weinberg equilibrium. Patients carrying the 825T allele had an increased left ventricular mass index (95.1 +/- 1.5 v 89.7 +/- 1.5 g/m2; P = .01) in comparison to those with CC genotype. The association between left ventricular mass index and 825T allele was independent of gender, age, BP, heart rate, alcohol intake, and physical activity.


CONCLUSIONS
In young patients with mild hypertension without heart disease the 825T allele is associated with an increased left ventricular mass index. These hypothesis-generating data suggest that GNB3 825T allele may be considered as one genetic marker predisposing to an increase in left ventricular mass in hypertensives, and justifies larger studies.
Semplicini
A
A
Department of Clinical and Experimental Medicine, University of Padova, Italy. andrea.semplicini@unipd.it
Siffert
W
W
Sartori
M
M
Monari
A
A
Naber
C
C
Frigo
G
G
Santonastaso
M
M
Cozzutti
E
E
Winnicki
M
M
Palatini
P
P
D000328:Adult; D000367:Age Factors; D019943:Amino Acid Substitution; D004452:Echocardiography; D005260:Female; D005838:Genotype; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D006973:Hypertension / Q000235:genetics*; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology; D008297:Male; D015398:Signal Transduction / Q000235:genetics*
D020962:Heterotrimeric GTP-Binding Proteins