Blood pressure variation in blacks: genetic factors.

Persons of African descent living in the Western hemisphere, including African Americans, have the highest prevalence of hypertension in the world. Debate continues as to whether it is their African ancestry or the Western environment that is more important in increasing the prevalence of hypertension in the African Diaspora above that of indigenous Africans as well as of fellow inhabitants in the Western hemisphere. Current data support that hypertension in African Americans, like that in other population groups, arises from the interaction of environmental factors with a susceptible physiology that is determined in part by genetic factors. Dietary sodium chloride (NaCl) is an important environmental factor, and the inability to prevent blood pressure from increasing to hypertensive levels in response to the comparatively high NaCl content of Western diets characterizes the majority of hypertensive African Americans. Studies discussed herein suggest a strong genetic component for the physiology of "salt sensitivity." Phenotypes that are indicative of this sensitivity are more common in African Americans than in Americans of European descent and in hypertensive African Americans compared with normotensive African Americans. Further studies are needed to more clearly define these genetic markers that determine salt sensitivity.