Associations of a human G protein beta3 subunit dimorphism with insulin resistance and carotid atherosclerosis.
OBJECTIVE
The C825T dimorphism of the gene encoding the human G protein beta3 subunit (GNB3) is associated with hypertension and obesity. Although these findings suggest an association with insulin resistance and atherosclerosis, this hypothesis has yet been tested only partially.


METHODS
To investigate this hypothesis, the C825T dimorphism was determined in a population of 932 middle-aged white subjects of middle European (Austrian) origin. Insulin sensitivity was measured with the short insulin tolerance test; intima-media thickness of the carotid artery and morphological plaque burden were measured by ultrasound.


RESULTS
Insulin sensitivity was found to be significantly lower in carriers of the T allele (3.55+/-1.27 versus 3.92+/-1.30%/min, P=0.012) in the group of male subjects with abdominal body fat distribution (waist-to-hip ratio >0.9). No effect was observed in women or men with a waist-to-hip ratio <0.9. Advanced carotid artery plaques were more frequent (odds ratio, 1.606; 95% confidence interval, 1.002 to 2.575; P=0.04) in carriers of the T allele regardless of sex. No effect was observed with regard to carotid artery intima-media thickness.


CONCLUSIONS
In summary, our results demonstrate that the GNB3 825T allele is associated with reduced insulin sensitivity in men with abdominal fat distribution and with more advanced carotid atherosclerosis in middle-aged white men and women.
Wascher
Thomas C
TC
Department of Internal Medicine, University of Graz, Graz, Austria. thomas.wascher@kfunigraz.ac.at
Paulweber
Bernhard
B
Malaimare
Liliane
L
Stadlmayr
Andreas
A
Iglseder
Bernhard
B
Schmoelzer
Isabella
I
Renner
Wilfried
W
D000328:Adult; D000368:Aged; D000483:Alleles; D001317:Austria / Q000453:epidemiology; D001794:Blood Pressure / Q000235:genetics; D001824:Body Constitution / Q000235:genetics; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics*; D015331:Cohort Studies; D015897:Comorbidity; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D007333:Insulin Resistance / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D015995:Prevalence; D021122:Protein Subunits / Q000235:genetics; D014463:Ultrasonography; D044465:White People / Q000235:genetics
D021122:Protein Subunits; D020962:Heterotrimeric GTP-Binding Proteins