New England Journal of Medicine study reveals genetic factors linked to chronic kidney disease
The study showed that having just one risk variant in a particular gene can significantly increase the risk of developing chronic kidney disease.
Kidney disease can kill quietly, with some people having no noticeable symptoms in its early stages. A new study published this week in the New England Journal of Medicine showed that having just one risk variant in a gene known as APOL1 can significantly increase the risk of developing chronic kidney disease.
Akinlolu Ojo, M.D., Ph.D., executive dean of the University of Kansas School of Medicine and a researcher with the school’s Department of Population Health, collaborated with researchers from the National Institutes of Health (NIH) to complete the study, which revealed a significant genetic risk factor for chronic kidney disease in people from Ghana and Nigeria.
“The increased odds of chronic kidney disease and focal segmental glomerulosclerosis in association with one APOL1 kidney risk allele is one of main findings of this study,” Ojo said. “If replicated in African Americans, it would imply that the number of individuals at increased risk of APOL1 kidney disease is one- to two-fold higher than previous estimates suggest.”
The study was conducted by researchers from the Human Heredity and Health in Africa (H3Africa) Kidney Disease Research Network, of which Ojo is a part.
More than one in seven U.S. adults have chronic kidney disease — an estimated 37 million Americans. African American, Hispanic American and Native American populations are more likely to develop the disease. And for those with diabetes or hypertension, there is a greater risk for developing kidney disease. As the kidneys are slowly damaged over time, they are unable to filter blood properly, leading to a buildup of waste in the body.
As the disease progresses, additional kidney functions are affected, such as the stimulation of red blood cell production and the maintenance of the body’s calcium balance. The disease can lead to other health issues such as stroke and heart attacks.
Previous research established that genomic variants in APOL1 increase the risk of developing chronic kidney disease among African Americans. However, not much is known about how these genomic variants affect people from West African countries, where many African Americans derive genetic ancestry. Studying how these genomic variants contribute to chronic kidney disease in West Africans and people with West African ancestry can also help inform the risk of kidney disease in many Americans.
“Our study provides data about West Africans that will help us better understand the risk of chronic kidney disease associated with APOL1 variants,” said Adebowale A. Adeyemo, MBBS, a co-author of the study and deputy director and chief scientific officer of the Center for Research on Genomics and Global Health at NIH’s National Human Genome Research Institute. “By comparing this study to previous studies involving the African American population, we can gain a deeper understanding of the effects of these high-risk APOL1 variants. Knowing your genetic risk for a disease, such as kidney disease, can help you make more informed decisions about your health and potentially lead to earlier interventions.”
More than 8,000 people from Ghana and Nigeria participated in the study, including nearly 5,000 people with chronic kidney disease of various stages and more than 800 people who had kidney biopsies that confirmed their disease.
The study found that nearly one-third of individuals in these two nations carry APOL1 variants that increase the risk of chronic kidney disease. While these APOL1 variants are seen most often in people of West African descent, other studies have found these variants in people from Europe, Asia and Central and South America.
“Findings in a particular study or with a specific ancestral group are often taken to be true for all humankind, but there is often substantial diversity even within specific ancestry or ethnic groups,” said Adeyemo. “This study highlights the importance of studying diverse populations around the globe when studying the genomics of human disease so that genomic medicine can equitably benefit people worldwide.”
The researchers also found that having a risk variant in one copy of the APOL1 gene increases the risk of developing chronic kidney disease, contrary to previous studies in the African American population, suggesting that both copies of APOL1 are needed to contain such variants to increase the overall risk. One risk variant increases the risk of chronic kidney disease by 18%, while two risk variants, one on each copy of APOL1, increases the risk by 25%.
These APOL1 risk variants also drastically increase the likelihood of developing a rare kidney condition called focal segmental glomerulosclerosis, which is scarring of the kidney tissues.
“Further research conducted with participants in the United States can help us understand how APOL1 variants affect the kidney,” says Paul Kimmel, M.D., program director at the National Institute of Diabetes and Digestive and Kidney Diseases and co-author of the study. “Overall, we hope that these findings can provide insight into improving the health of patients at risk for and with kidney disease.”