Why African Americans Have More ESRD
Reseachers have identified, for the first time, gene variations that explain the increased burden of kidney diseases among African Americans.
The findings come from two studies whose findings appear in Nature Genetics (2008; published online ahead of print). One study was conducted by NIH-funded researchers at Johns Hopkins University in Baltimore and the other was conducted by researchers at NIH. Both studies found an association between variations in MYH9, a gene on chromosome 22, and non-diabetic end-stage renal disease (ESRD) in African Americans.
The studies showed no link between the gene variations and diabetic ESRD. “This finding suggests that the mechanisms leading from onset of chronic kidney disease to kidney failure may differ based on the inciting cause,” said study senior author Rulan Parekh, MD, associate professor of medicine at Johns Hopkins. “Discovery of the gene and its association with kidney disease will lead to future studies to better understand the biology of kidney disease progression and ultimately may direct drug therapy and potential screening of patients.”
In the Johns Hopkins study, researchers analyzed the genomes of 1,372 African Americans with ESRD and a control group of about 800 African Americans without ESRD. In the NIH study, researchers first analyzed the genome of 190 American Americans with focal segmental glomerulosclerosis (FSGS) and 222 without the disease and to localize the region of interest to a specific chromosomal region and next identified the MYH9 gene using a larger group of patients with FSGS.
The NIH group identified MYH9 as major effect gene associated with FSGS and HIV-1-associated nephropathy (HIVAN) and extended this association to hypertension-associated ESRD, but not diabetic ESRD. The risk variants are present in 60% of African Americans versus only 4% in whites. The authors concluded that MYH9 variations “substantially explains” the increased burden of FSGS and hypertensive ESRD among African Americans.