Manifestations and aetiology of hypertension in the Coloured and Bantu

Hispanic Americans living in the United States and their risk for obesity, diabetes and kidney disease: Genetic and environmental considerations

The Hispanic American, the largest minority population in the United States, is at increased risk for obesity, diabetes and end-stage renal disease. Here we review genetic and environmental factors that might account for their increased risk for these conditions. Whereas many environmental and genetic factors have important roles in driving the increased risk for obesity and kidney disease in this population, a case is made that excessive intake of sugary beverages is a contributory cause. Studies focusing on decreasing intake of sugary beverages among the Hispanic American could potentially reduce renal and cardiovascular complications in this population.

Prevalence of hypertension in the urban and rural Zulu

In a house-to-house study of 994 urban Zulus the prevalence of hypertension according to WHO criteria was 25% (23% men, 27% women). In a rural Zulu study of 987 the prevalence age corrected to the urban distribution was 9.4% (8.7% men, 10% women). Thus there was a pronounced difference between the prevalence of hypertension in the urban and rural Zulu (p less than 0.0005). There was an earlier onset of hypertension in the urban compared with the rural Zulu. Contrasting biosocial factors in the urban and rural Zulu could explain the differences in prevalence. Our study suggests that hypertension is not a major health problem in rural Zulus. Large-scale case finding and intervention programmes should be confined to the urban black population of South Africa.

The relative importance of genetic and environmental factors in hypertension in black subjects

Essential hypertension is the most important cardiovascular disease in black subjects. The types of presentation, the pattern of organ involvement and the subsequent complications are similar in black races. The response (or lack of response) to different types of treatment are also alike in blacks when compared with caucasians. Striking racial differences are observed in the plasma and intracellular electrolytes, cation transmembrane transport, salt taste threshold, plasma renin activity and urinary kallikrein activity. The similarities within the black racial groups are very likely to be genetic, although the pattern of inheritance remains controversial. Differences, however, occur in the prevalence and severity of the disease among the black racial groups. That these differences are due partly to environmental causes can not be disputed because even within the same ethnic groups changing patterns are observed in the prevalence of hypertension, in the course of urbanization of rural communities, or on moving from a previously rural to an urban environment. Consequently, genetic factors may be the only important considerations in the severity of hypertension in black subjects.