Title: Why Do Black Americans Have Higher Prevalence of Hypertension? | Hypertension
Headings: Why Do Black Americans Have Higher Prevalence of Hypertension?
Why Do Black Americans Have Higher Prevalence of Hypertension?
An Enigma Still Unsolved
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Content: This hypothesis is hard to confirm or refute. The association between genetic traits and renal outcomes has been reported in black Americans versus white Americans. Kao et al 6 and Kopp et al 7 reported an association between a genetic variation of the MYH9 region on chromosome 22 with focal segmental glomerulosclerosis, a condition previously attributed to “hypertensive nephrosclerosis” and found much more frequently in black patients with end-stage renal disease than in whites with end-stage renal disease. The attributable risk for carriage of this MYH9 haplotype was found in 74% of blacks and in only 4% of whites with focal segmental glomerulosclerosis. More recently, using much more complete genomic sequences, Tzur et al 8 reported missense mutations in the APOL1 gene, which neighbors the MYH9 gene on chromosome 22 in patients with focal segmental glomerulosclerosis. These genetic defects may account for the higher propensity of blacks to develop end-stage renal disease, which may then induce hypertension, rather than hypertension being responsible for the renal damage. Nonetheless, the possible role of these or other genetic defects in the large majority of blacks without focal segmental glomerulosclerosis or end-stage renal disease remains unknown, particularly with regard to differences in the renal handling of sodium between normotensive black subjects living in Africa and the United States. Differences in exposure to the environment and habits between blacks and whites have also been proposed to explain their differential prevalence of hypertension. Many potential reasons have been reported, such as socioeconomic status, dietary habits, social network, stress, and health behaviors. Among the consequences of differential dietary habits, excess adiposity emerges as a natural candidate to explain the higher prevalence of hypertension in blacks, who have a 51% greater prevalence of obesity than whites.