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We have recently reported that there are significant genetic influences on the population variation in blood pressure in black twins in Los Angeles. The present cross-sectional study was undertaken to replicate these findings in a black twin population that lives in a different biosocial environment We chose the Caribbean island nation of Barbados, where 96% of the population is black, the literacy rate is 99%, and the access to health care is guaranteed. The goals were 1) to test the feasibility of twin studies in blood pressure research in a developing country and 2) to estimate the relative contribution of genes and environment to blood pressure variability in blacks in the Caribbean. The names of 200 twin sets were obtained with the assistance of community resources Including a twin club, by media advertisement, and by asking people at public blood pressure screenings if they knew any twins. By using these methods, we identified 200 sets of twins. Of these, 37.5% (75/200) met our criteria for study. Although 97% of the sets of twins (73/75) said they were willing to participate, only 69% (52/75) were able to be scheduled during the 1 week of the study when the full team of investigators was in Barbados. Of those scheduled, 83% (43/52) were examined. Examination included medical history, physical examination, recumbent blood pressure measurements by two observers, anthropometric measurements, 24-hour urine collections for sodium and potassium tests, and blood tests for zygosity. Zygosity was determined by history, multiple genotyping, or both, which classified 21 pairs as monozygotic (13 male and eight female) and 22 pairs as dizygotic (11 female and 11 male). The average age was 29±9.5 (±SD) years, average height was 169±92 cm, average weight was 69±3.8 kg, average triceps skin-fold thickness was 11.3±6.5 mm, average arm circumference was 29±3.9 mm, average systolic blood pressure was 118±103 mm Hg, average sodium excretion was 131±653 mM/24 hours, and average potassium excretion was 46±17 mM/24 hours. In male twins, the quantifiable traits such as height, weight, triceps skin-fold thickness, arm circumference, and systolic blood pressure were all under significant genetic influence. The intraclass correlation for systolic blood pressure in all twin pairs was 0.67 (p<0.001), strong evidence for family aggregation of blood pressure. Twin analysis suggested that the major source of variance for systolic blood pressure between individuals was genetic, and heritability in males was estimated to be 70%. The heritability of blood pressure was not explained by any of the other measured variables. Within-twin-pair comparisons did not suggest that the twin with the highest blood pressure was taller, heavier, or consumed more sodium or less potassium. The twin with the thickest triceps skin folds, however, had a higher blood pressure. These results suggest that in blacks in the Caribbean, as in the United States, the major source of variation in blood pressure in the population is inherited factors and that twin studi...

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The Omron HEM-711 DLX home Blood pressure monitor was tested using the European Society of Hypertension International Protocol in 33 patients. The average error was 0.9+/-5.2 (SD) (range: -12 to 10 mmHg)/-0.8+/-5.6 (-19 to 8). It can be recommended for use by patients. With all automatic devices it is, however, important to validate its accuracy in each individual patient who uses it.

Population blood pressure variation is most likely due to multiple genes. This is likely the reason why monogenic testing with the angiotensinogen (AGT) gene polymorphisms on chromosome 1 (1q42-43), especially M235T, has met with negative results, especially in those of African descent. The RH blood group system, also on chromosome 1 (1 p36.2-34), has likewise been associated with blood pressure variation in AfricanAmericans and with the rise in blood pressure with age in whites. Using a random sample of the population, we investigated the combined effects of single and combined variation of the AGTN M235T and RH genotypes on blood pressure, lipids, and lipoprotein concentrations in Afro-Caribbeans aged 18-60 years from the island nation of Dominica. In monogenic analysis, AGT M235T was not associated with blood pressure. However, it was associated with HDL (MM 42723, MT 44712, TT 52714 (P ¼ 0.002)). RH genotype was significantly associated with systolic blood pressure (P ¼ 0.006) and Apo-A (P ¼ 0.003). These effects remained after adjustment for age, gender, weight, and BMI. In the polygenetic analysis, AGT M235T and RH were significantly associated with systolic blood pressure (P ¼ 0.037; interaction effects, P ¼ 0.068). The association of the AGT M235T with blood pressure across RH blood group haplotypes was then tested. Of the five RH haplotypes available for analysis, the AGT M235T was significantly associated with blood pressure within the ''D'' haplotype (P ¼ 0.01). The RH blood group and gender were significantly associated with systolic blood pressure and Apo-A levels (P ¼ 0.005 and 0.012, respectively). All interactions were independent of age and weight. In conclusion, we demonstrate a significant association of AGT M235T with blood pressure and cholesterol metabolism in an Afro-Caribbean population in the ''genetic context'' of the RH blood group system. Further investigation of these interactions may help understand the effects of genetic factors on cardiovascular risk in African-derived and other populations.

The Omron Elite 7300W home blood pressure monitor passed the ESH validation protocol and can be recommended for patient use.