Researchers target kidney disease in African-Americans

Apr. 21, 2014 @ 01:00 AM

It took Dr. Barry Freedman more than a decade to help disprove a long-held belief that high blood pressure commonly caused non-diabetic kidney disease in African-Americans.
It is now widely accepted that a genetic link is the cause, so Freedman and his colleagues at Wake Forest Baptist Medical Center in Winston-Salem are taking on a new challenge: how to turn that knowledge into a cure for kidney disease.
The numbers show the importance of the work: Approximately 26 million American adults have chronic disease of the kidneys, the organs that remove waste products and excess fluid from the body. When 85 to 90 percent of kidney function has been lost — a condition known as end-stage renal disease — patients typically receive dialysis, a time-consuming and sometimes painful way of cleansing their systems. And, according to the National Institutes of Health, while African-Americans make up about 13 percent of the U.S. population, they account for 32 percent of the people with kidney failure. 
Freedman, professor and chief of nephrology at Wake Forest Baptist, was part of a team of scientists that in 2010 first reported the role of two variants in the gene APOL1 as a major risk factor for kidney failure in African-Americans.
Even so, not all people who have the gene variants — which are found in about 15 percent of African-Americans but are exceedingly rare in Caucasians — will develop kidney disease, which means there is a “second hit” that triggers the disease, Freedman said.
“We know there is a second factor,” he said. “Now our job is to find it.”
Freedman said he and his research team are looking closely at viruses in urine that may offer protection from kidney disease, “kind of like a defense shield.”
He said that these viruses may be absent in some individuals with the APOL1 gene variants who develop kidney disease and that studying the interactions between viruses and genes could determine why some people get kidney disease while others don’t.
If that happens, Freedman said, “I think we can rapidly develop a cure or at least a way to slow progression of this disease.”
At present, the best available treatment for a patient with end-stage renal disease is a transplant from a live donor. But these can be difficult to obtain, especially for African-Americans. According to a study published by the National Kidney Foundation, while African-Americans account for more than one-third of the people on kidney waiting lists, they received only 14 percent of the living kidney transplants performed in 2011.
Dr. Amber Reeves-Daniel, a Wake Forest Baptist nephrologist, has done research into possible reasons for this disparity.
In one study, she found that individuals with private insurance were three times more likely than those without private coverage to receive living kidney transplants. But the research also showed that African-Americans with private insurance were 14 times more likely to receive live kidneys than African-Americans without it and that African-Americans with only Medicaid were very unlikely to receive living kidney transplants.
In another project, her research team found that African-Americans donated almost exclusively to family members and were more likely to donate to parents, as compared with Caucasian kidney donors.
Both studies were based on data from cases at Wake Forest Baptist.      
“I think it has a lot to do with economics and cultural differences,” Reeves-Daniel said. “But as you do research, you find more unanswered questions.” 
LaTasha Siler of High Point, an African-American who donated a kidney to her mother, Mary Sinclair of Winston-Salem, in December 2011, believes that there is an education factor involved in becoming a donor and that many people, especially African-Americans, don’t understand the process and thus shy away from it.
“It’s easy to say no to what you don’t understand,” Siler said. “If I hadn’t gone out and done my own research, there would have been critical factors that I would have missed out on. If you have the knowledge, it makes your decision that much easier. I don’t think enough African-Americans see it as a possibility to live a long, normal, healthy life after being a living donor.”
Before deciding whether to donate a kidney to her mother — who underwent dialysis for years both before and after her body rejected a kidney transplanted from a deceased donor in 2007 — Siler was tested at Wake Forest Baptist to determine if she was a donor match for her mother and if she had the two variants in the APOL1 gene. When the answers came back — yes and no — Siler made her choice.
Today, more than two years later, both donor and recipient are doing fine.
Siler said she hopes the research being conducted by Freedman and his colleagues at Wake Forest Baptist is productive.
“We’ve got to learn how to prevent kidney disease,” she said. “It’s very personal to me.”