Abstract-We estimated the heritability of ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) in east African families with at least 2 hypertensive siblings and living in the Seychelles islands (Indian Ocean). The sample consisted of 314 individuals (147 men and 167 women), both normotensive and hypertensive, from 76 pedigrees (meanϮSD of 4.1Ϯ2.8 persons per pedigree). After a 2-week off-treatment period, daytime and nighttime ambulatory blood pressure (BP) was monitored. Office BP was measured with a standard mercury sphygmomanometer. We estimated by maximum likelihood the age-and sex-adjusted heritabilities from the additive polygenic component of the variance of the traits allowing for the presence of other familial correlations. We also adjusted for ascertainment (ie, for the fact that 2 siblings had to be hypertensive) and examined the effect of adjusting for body mass index, 24-hour urinary excretion of sodium and potassium, plasma renin activity, and plasma aldosterone concentration. Heritability estimates (ϮSE) for ambulatory SBP, DBP, and PP were, respectively, 0.37Ϯ0.12/0.24Ϯ0.12/0.54Ϯ0.12 for daytime and 0.34Ϯ0. Key Words: blood pressure monitoring, ambulatory Ⅲ genetics Ⅲ ethnicity Ⅲ blacks H ypertension, which affects approximately one-third of the adult population in Western countries, 1 is now becoming a substantial burden in African countries as well, with prevalence ranging from 16% to 32% among adults. [2][3][4][5] Because individuals of African descent are more prone to hypertension-related complications than whites, 6 -8 a better understanding of the familial aggregation of blood pressure (BP) in this ethnic group is of particular importance for unraveling the genetic variants influencing BP.Heritability is a measure of familial aggregation caused by genetic factors. Narrow sense heritability is the proportion of the total phenotypic variance that is caused by the additive genetic variance (ie, that part of the genetic variance caused by the average effects of individual alleles, which reflects transmissible resemblance between relatives). A high heritability identifies good candidate phenotypes for further genetic studies. Studies conducted so far in Africa 9 -11 used conventional BP measurement and found heritability estimates ranging from 0.34 to 0.45 for systolic BP (SBP) and from 0.29 to 0.43 for diastolic BP (DBP).Two studies have measured the heritability of ambulatory BP in nontwins 12 . 13 Daytime heritability estimates for SBP/ DBP were 0.32/0.25 in a study of black affected sibpairs 12 and 0.33/0.22 in a study of Swedish families. 13 Nighttime heritability estimates for SBP/DBP were 0.69/0.51 in the former 12 and 0.37/0.32 in the latter. 13 To date, only the Swedish study 13 has reported the heritability of ambulatory pulse pressure (PP) (0.53/0.34 for daytime/nighttime).We estimated the heritability of ambulatory SBP, DBP, and PP in families of African descent with at least 2 hypertensive siblings and living in the Seychelles islands (...

Hypertensive patients of African descent responded better to LIS than to HCT. Men responded better to LIS than to HCT and women responded similarly to both drugs.