Combined effects of endothelial nitric oxide synthase gene polymorphism (G894T) and insulin resistance status on blood pressure and familial risk of hypertension in young adults: The Bogalusa Heart Study

Impaired endothelial function with decreased nitric oxide production is sha red by insulin resistance and essential hypertension. Although there are li mited data on the association between the endothelial nitric oxide synthase (eNOS) G894T polymorphism and hypertension, information is absent on the c ombined effects of eNOS G894T genotype and insulin resistance status on blo od pressure (BP) levels and the familial risk of hypertension. This aspect was examined in a community-based sample of 1021 unrelated African American and white young adults aged 19 to 38 years. African Americans displayed a lower frequency of the T894 allele than whites (0.105 v 0.324, P < .001). A fter adjusting for sex, age, and body mass index (BMI), noncarriers versus carriers of the T894 allele had significantly higher systolic (SBP), diasto lic (DBP) BP and mean arterial pressure (MAP) levels (111.7 v 109.2 mm Hg f or SBP; 73.6 v 72.3 mm. Hg for DBP; 86.3 v 84.6 mm Hg for MAP), with both A frican Americans and whites showing similar trends. This association was mo dulated by insulin resistance status, measured by the homeostasis model ass essment of insulin resistance (HOMA IR) using fasting insulin and glucose. Subjects with high insulin resistance (above the median HOMA IR) showed sig nificantly greater differences in BP levels between noncarriers and carrier s of the T894 allele. Furthermore, the G894T genotype and insulin resistanc e also showed a combined effect on the prevalence of parental hypertension, a measure of familial risk, with noncarriers versus carriers in the high i nsulin resistance group showing higher prevalence (70.5% v 51.3%, P = .006, adjusted for race). Thus, the allelic variation (G894T) in the eNOS gene l ocus in conjunction with insulin resistance may be one factor contributing to the predisposition to hypertension. Am J Hypertens 2001;14:1046-1052 (C) 2001 American Journal of Hypertension, Ltd.