Association between angiotensin II type I receptor polymorphism and resting hemodynamics in Black and White youth

Objectives: An angiotensin II type I receptor polymorphism (AGTR1/A1166C) was previously found to be associated with hypertension. The purpose of this study was to investigate the relationship between this polymorphism and resting measures of hemodynamics in normotensive youth. Design: Subjects were 41 Whites (mean ± SD: 18 ± 3 y old, 26 males) and 73 Blacks (19 ± 2 y old, 55 males) with a positive family history of hypertension. Methods: Hemodynamic measures included resting systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR). Results: Allele frequencies were significantly different (x² = 14.10, P≤.001) between Whites and Blacks (.23 vs. 06 for the C allele, respectively). For all subsequent analyses, subjects were categorized into two genotype groups, carriers and non-carriers of the C allele, because only two Whites and no Blacks were homozygous for the C allele. Genotype frequencies were significantly different (x² = 12.66, P≤.001) between Whites and Blacks (.41 vs. 12 for the carriers, respectively). Among Whites, univariate analyses of covariance, using body mass index and age as covariates, indicated that carriers of the C allele compared to non-carriers, had a higher DBP (61.6 ± 6.7 VS 57.8 ± 6.2 mm Hg, P≤.05) and HR (68.0 ± 10.5 vs 61.1 ± 8.1, P≤.05). Genotype was not associated with resting hemodynamic measures in Blacks (all P values>.05). Conclusions: These results are consistent with findings that have typically involved White adults, and demonstrate that the renin system does not seem to play as great a role in BP control in Blacks as it does in Whites.