September 1, 2016
A large international collaboration marks the first study of kidney function involving individuals from four continents. After examining kidney function in African, Asian, European and Hispanic individuals, researchers found 20 genetic regions that affect kidney function and are common across all ethnic ancestries.
The full paper, titled “Trans-ethnic fine-mapping highlights kidney function genes linked to salt sensitivity,” was published online Sept. 1 by the American Journal of Human Genetics.
The study’s lead author is Nora Franceschini, MD, MPH, research associate professor of epidemiology at the UNC Gillings School of Global Public Health. Another co-author from the Gillings School is Jianwen Cai, PhD, Cary C. Boshamer Distinguished Professor of biostatistics and interim chair of the biostatistics department.
Franceschini points out that chronic kidney disease affects nearly 10 percent of the global population, making it a major public health burden – and making the study results the potential start of a large break-through.
“Our findings are remarkable because they show similar genetic effects for kidney function across individuals of diverse ancestries,” she says. “The results support a common genetic background for kidney function across populations.”
The study methodology used trans-ethnic statistical models to examine the estimated glomerular filtration rate – a measure of kidney function used to define chronic kidney disease – in 71,638 individuals of multiple ancestries. A series of nine population-based genome-wide association studies explored the genetic variation in kidney function across populations to better understand why some populations are more likely than others to acquire kidney disease.
The researchers learned that there are 20 genomic regions associated with kidney function, which appear across all populations.
The investigators also conducted experimental models to learn more about how these genes function. They found that the kidney expression of two specific genes decreased in a salt-sensitive mouse strain following exposure to a high-salt diet. While precise cause and effect must still be determined, this indicates that salt sensitivity is a potentially important marker for the biological processes that affect kidney function and chronic kidney disease in humans.
Knowing that an individual’s sensitivity to sodium intake may imply additional information about their kidney function could have implications for future diet recommendations.
“The key takeaway here is that we need to study diverse populations,” Franceschini says. “True public health research aims to understand all populations and contribute to informed decisions about the health care of all people.”