 | | Dr. Opeyemi Olabisi in the Duke Molecular Physiology Institute in Durham, N.C. He has lost friends and family members to kidney disease.Cornell Watson for The New York Times |
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Kidney Disease Disproportionately Affects Black Americans |
In a Zoom call this spring with 19 leaders of A.M.E. Zion church congregations in North Carolina, Dr. Opeyemi Olabisi, a kidney specialist at Duke University, asked a personal question: How many of you know someone — a friend, a relative, a family member — who has had kidney disease? |
The anguished replies tumbled out from the assembled pastors: |
A childhood friend died, leaving a daughter behind. |
A father and sister felled by the disease. |
Three cousins and a brother-in-law on dialysis. |
None of this surprised Dr. Olabisi, who disclosed that he, too, had lost family members to the disease. His best friend, who had taught him to ride a bike in his native Nigeria, died of kidney failure in his early 30s. |
Kidney specialists have long known that Black Americans are disproportionately affected by kidney disease. While Black people make up about 12 percent of the U.S. population, they comprise 35 percent of Americans with kidney failure. Black patients tend to contract kidney disease at younger ages, and damage to their organs often progresses faster. |
Social disparities and systemic racism contribute to this burden, but there is also a genetic factor. Many with sub-Saharan ancestry have a copy of a variant of the gene APOL1 inherited from each parent, which puts them at high risk. Researchers have known for a decade that APOL1 is one of the most powerful genes underlying a common human disease. |
But there is hope now that much of this suffering can be alleviated. As many as 10 companies are working on drugs to target the APOL1 variants. And Dr. Olabisi has a federal grant to test whether baricitinib, a drug that treats rheumatoid arthritis, can help kidney patients with the variants. |
Yet the promise of treatments comes with difficult questions. |
Should genetic testing be offered and, if so, to whom? Although the variants increase risk, they do not preordain kidney disease. If someone knows that they have the variants, will they live in fear of kidney failure? |
There are as yet no proven ways to reduce the risk of kidney disease in those with two copies of the variants. Rigorous control of blood pressure — a major risk factor for progression of kidney disease — can be difficult to achieve in those who have the variants. |
"Now we know that the reason you can't get your blood pressure down is because you have APOL1 kidney disease that is ferociously raising your blood pressure," said Dr. Jeffrey Kopp, a kidney researcher at the National Institutes of Health. "It's not your fault." |
Despite their elation at the progress being made, some experts like Dr. Olabisi say that a laser focus on variants may let policymakers ignore the social and economic disparities underlying the disease. |
But, he added, "we don't want to pretend that the biology doesn't exist." That, he said, "would not be doing the community any good." |
While it has long been known that kidney failure occurs in African Americans five times as much in as it does in white Americans, "We had never been able to understand all the reasons," said Dr. Neil Powe, a professor of medicine and an epidemiologist at the University of California, San Francisco. |
Researchers began looking for a genetic cause. Finally, a little more than a decade ago, a Havard team led by Giulio Genovese, Dr. David Friedman and Dr. Martin Pollak found it: variants of APOL1 that ramped up the gene's activity. |
It was a complete surprise. APOL1 is part of the immune system and can destroy trypanosomes — protozoa that can cause illnesses. But no one expected it to have anything to do with the kidneys. |
It turns out that the variants rose to a high frequency among people in sub-Saharan Africa because they offer powerful protection against deadly African sleeping sickness, a disease caused by trypanosomes. It is reminiscent of another gene variant that protects against malaria but causes sickle cell disease in those who inherit two copies. That variant became prominent in parts of Africa and other areas of the world where malaria is common, but sickle cell variants are much less common than APOL1 risk variants. |
About 39 percent of Black Americans have one copy of the gene's risk variants; another 13 percent, or nearly 5.5 million, have two copies. Those with two copies are at increased risk for fast progressing kidney disease that often starts in young adulthood. Approximately 15 percent to 20 percent of those with two copies develop kidney disease in their lifetime. |
 | | Twin brothers Martin, left, and Malcolm Lewis both have lupus. But their kidney disease may be caused by a gene, not an autoimmune disorder.Amir Hamja for The New York Times |
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"What nature gave with one hand, it took away with the other," Dr. Olabisi said. |
One way to treat kidney disease might be using medicines that block the gene and its variants from acting in the body. But researchers had to find out if APOL1 was necessary for kidney function. If it was, drugs that blocked it might do more harm than good. |
Researchers found an answer: A farmer in India had no APOL1 gene. His kidneys were totally healthy. |
Often, in drug development, Dr. Friedman says, the drug dose has to be fine tuned — too much is dangerous and too little is useless. The discovery of the farmer, he said, "tells you you can probably drive the level of the APOL1 protein very low." |
But ethical issues have tempered some experts' enthusiasm about the genetic discoveries. |
Harriet A. Washington, a lecturer in ethics at Columbia University and author of the book "Medical Apartheid," worries that knowledge of the role of APOL1 variants can drive the medical establishment toward "a blame-the-victim approach signaling an inherent flaw in African Americans." |
The implication, she said: "This is something happening in nature, so what can we do about it?" Such an attitude, she added, "invites futility and absolves health care from treating sufferers." |
Joseph L. Graves, Jr., a professor of biological sciences at North Carolina Agricultural and Technical State University, raised another issue. "We don't want to fall into the myth of the genetically sick African," he said. |
Read the rest of the story here. |
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