Glycogen synthase polymorphism, insulin resistance and hypertension

The A₂ allele of the human glycogen synthase gene may be associated with hypertension in diabetic and nondiabetic Finnish subjects. The prevalence of the A₂ allele was investigated in 64 non-diabetic hypertensive subjects with borderline hypertension or established hypertension. Ambulatory blood pressure was performed on all subjects. Insulin sensitivity index (S(I)) was determined in subjects with borderline hypertension. The DNA fragment containing the XBaI restriction site was amplified by the polymerase chain reaction, digested by the XBaI enzyme and compared by gel electrophoresis with a positive control from Finland. Mean age ± SD for age, S(I) and ambulatory blood pressure were respectively: 39 ± 10 yrs, 60 ± 30 min^-1/(nmol/mL) and 132 ± 7/83 ± 6 mmHg. Sixteen of the subjects were insulin resistant as determined by S(I) < 70.0 and they had significantly higher BP and BMI than insulin sensitive subjects. The A₂ allele of the glycogen synthase was not detected in any subject. This suggests that the relation between the XBaI polymorphism of the glycogen synthase gene, insulin resistance and elevated blood pressure may be restricted to a limited and genetically uniform Finnish population.