Worsening Kidney Disease in Blacks Linked to Gene Variant

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DENVER—A common gene variant appears to be associated with a sharply increased risk of progressive kidney disease in African Americans (AAs) with hypertensive nephrosclerosis.

Researchers from Johns Hopkins Bloomberg School of Public Health presented new data showing that the variant MYH9 gene is found in 55% of AAs and is associated with an increased risk of CKD (chronic kidney disease) progression.

“We found that individuals with the common genotype were approximately 1.5 times more likely to have progressive kidney disease than those with other genotypes,” said lead investigator Brad Astor, PhD, MPH, Associate Professor of Epidemiology and Medicine at Johns Hopkins University in Baltimore.

Dr. Astor and his colleagues performed genetic studies to identify variant forms of the gene MYH9 in 706 AAs with hypertensive nephrosclerosis. The patients were part of the larger African American Study of Kidney Disease and Hypertension (AASK) trial. In the AASK patients, several MYH9 gene variants were related to the risk of decreased kidney function or end-stage renal disease (ESRD). Subjects with one MYH9 variant were also found to be much more likely to have other variants as well.

The same MYH9 gene variant previously linked to non-diabetic ESRD was also associated with an increased risk of progressive kidney disease in the AASK patients. The risk of death, ESRD, or a significant drop in kidney function was 50% higher in subjects with the MYH9 gene variant than in subjects without the variant gene. The MYH9 gene variant was associated with progressive kidney disease independent of age, sex, or treatment for high blood pressure.

“Associations between specific gene variation and outcomes can help us understand the pathophysiologic processes involved in progressive kidney disease and may lead to areas of research to slow or prevent progressive kidney disease,” Dr. Astor said. Other studies suggest that a neighboring gene, called APOL1, may actually be the causal gene for non-diabetic ESRD/CKD in AAs. MYH9 may simply be a marker of the causal gene. Further studies are needed to dissect the contribution of APOL1 and MYH9 in CKD in AAs and to determine the utility of the APOL1/MYH9 locus in diagnosis and management.

Astor said the findings from this study are important because all the subjects were in a trial where their blood pressure was well managed and patients were closely monitored for the potential risks and benefits of high blood pressure medications. However, he cautioned that much more research is needed before clinicians can start routinely testing for these gene variants. “It's too soon to advocate global screening for these variations,” Dr. Astor said.
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