Genetic Biomarker Links Kidney Disease to African Descent

In the previous two years American scientists had traced a genetic link to Africa, when they discovered that end stage kidney diseases (ESKD) is associated with the gene MYH9 found on chromosome 22, which explained the higher prevalence of the disease in those of African Hispanic descent. Previously, scientists had attributed this phenomenon to environmental factors such as culture, or diet.

Israeli and American scientists identified a new biomarker that can help America's medical community to predict who is likely to develop a potentially fatal, end-stage kidney disease most prevalent among Black Americans.

In areas in the United States where there are equal numbers of blacks and whites, more people of African descent will be using a hospital's dialysis machines, followed by those of Latino heritage, with whites in the minority for this condition, said Dr. Doron Behar of the Rambam Medical Center (Haifa, Israel), coauthor of the new study.

In North America alone, there are about 40 million people with chronic kidney disease at varying stages of development. About half of these will go on to develop ESKD. The toll on the healthcare system is enormous and the pain and suffering from treatments and the wait for a transplant can be almost unbearable.

ESKD requires either long-term dialysis or a kidney transplant to keep patients alive and remains fatal in parts of the world where such advanced treatments are not available. Black Americans have about a four-fold higher rate of developing the end-stage disease, and Hispanic-Americans an approximately two-fold higher rate, than Americans of European ancestry.

Interestingly, four years earlier the Israeli scientists in the study found that unlike African-Americans, Ethiopian Africans appear to be protected from end-stage kidney disease. This suggests that something in their genes--also African at the core--may hold the clue as to how kidney health is genetically programmed.

Dr. Behar expects that the genotyping of those who come to their clinics will help nephrologists to save more lives, by providing them with the information to understand and evaluate the risks that their patients may be facing. Knowing who is at risk can help physicians prescribe the appropriate medication to minimize damage to kidneys, as certain drugs can actually cause severe kidney damage in some people.

The authors wrote, ''These findings strengthen the contention that a sequence variant of MYH9, common in populations with varying degrees of African ancestry admixture, and in strong linkage disequilibrium with the associated single nucleotide polymorphisms (SNPs) and haplotypes reported herein, strongly predisposes to nondiabetic ESKD.

The new collaborative study was published in the May 1, 2010 issue of the journal Human Molecular Genetics.

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Rambam Medical Center