Role of genetic and environmental factors in the increased blood pressuresof Bolivian blacks

The tendency toward hypertension or higher blood pressure is more common in blacks than whites. The factors that account for these differences are att ributed to both environmental and genetic factors. To clarify this issue, a n anthropological study of black and nonblack populations in the lowland vi llage of Chicaloma, northeastern Bolivia at a midaltitude of 1,800 m was co nducted. The study included 159 subjects, of which 79 were black and 80 wer e nonblack, 17-78 years. The study suggests the following: (1) the socioeco nomic status of blacks as measured by an ownership index is greater than th at of nonblacks, (2) blacks had higher average systolic and diastolic blood pressures than nonblacks and showed an age-associated increase in blood pr essures, (3) the prevalence of hypertension was higher for blacks (7-6%) th an nonblacks (1.3%), but three times lower than among blacks in the United States, (4) skin reflectance is inversely related to blood pressures so tha t contrary to what has been suggested the darker the skin color, the higher the blood pressures even at comparable levels of affluence. These findings together suggest that genetic factors predispose black individuals to incr eased blood pressures, but the expression of clinical hypertension is influ enced by adverse unaccounted environmental factors. (C) 1999 Wiley-Liss, In c.