ABSTRACT
The C-824T single nucleotide polymorphism in the promoter region of the tyrosine hydroxylase gene has been associated with hypertension. It is well documented that African South Africans exhibit a higher prevalence of hypertension than Caucasians. However, the possible role of this mutation on 24-hour ambulatory blood pressure (AMBP) has not been investigated in African South Africans. Blood samples of 409 South Africans were screened for the mutation. Ambulatory blood pressure and lifestyle factors were also measured. Africans had higher incidence of hypertension and higher occurrence of the mutation. However, the contribution of the tyrosine hydroxylase C-824T single nucleotide polymorphism to hypertension could not be confirmed in our cohort.
Subject(s)
Black People/genetics , Blood Pressure/genetics , Hypertension/genetics , Tyrosine 3-Monooxygenase/genetics , White People/genetics , Adult , Black People/statistics & numerical data , Blood Pressure Monitoring, Ambulatory , Cohort Studies , Female , Humans , Hypertension/ethnology , Male , Middle Aged , Polymorphism, Single Nucleotide , Promoter Regions, Genetic/genetics , South Africa/epidemiology , White People/statistics & numerical dataABSTRACT
Silent myocardial ischemia is a predictor of subclinical atherosclerosis driven by increased cardiovascular risk markers, although still unknown in Africans. The aim of this study was to assess if cardiovascular risk markers will be associated with subclinical atherosclerosis. African men were stratified into (i) 24-hour silent ischemia (SI, n = 38) and (ii) without (nSI, n = 40) groups. Ambulatory blood pressure (BP), SI, 12-lead resting electrocardiogram, ultrasound carotid intima-media thickness (CIMT) measurements, and fasting blood samples were obtained. Above-normal cardiovascular risk markers, that is, glucose level, heart rate, BP, and CIMT, were evident in men with SI. Hypertension prevalence was 89% in the African SI men as opposed to 64% in the nSI men. Regression analyses revealed that only SI events in SI men explained 35% (95% confidence interval [CI]: 0.22;0.52) of the variance in CIMT, while in all African men it explained 29% (95% CI: 0.19;0.39). In conclusion, SI was associated with structural vascular disease in African men. This could imply that SI is not necessarily driven by hypertension in African men but through other possible mechanisms such as increased sympathetic nervous system activity.
