Genetic variation increases risk of kidney disease progression in African Americans

New research provides direct evidence that genetic variations in some African Americans with chronic kidney disease contribute to a more rapid decline in kidney function compared with white Americans. The research, led by investigators from the University of Maryland School of Medicine and Johns Hopkins University, may help explain, in part, why even after accounting for differences in socio-economic background, end-stage kidney disease is twice as prevalent among blacks as whites.
‘What we found is pretty remarkable — that variations in a single gene account for a large part of the racial disparity in kidney disease progression and risk for end-stage kidney disease,’ says co-lead author and nephrologist Afshin Parsa, M.D., M.P.H., assistant professor of medicine and member of the Program in Personalized and Genomic Medicine at the University of Maryland School of Medicine. ‘If it were possible to reduce the effect of this gene, there could be a very meaningful decrease in progressive kidney and end-stage kidney disease within blacks.’
Previous landmark discoveries revealed that two common variants within a gene called apolipoprotein L1 (APOL1) were strongly associated with non-diabetic end-stage renal disease in blacks. Having only one copy of the variant APOL1 gene variant is associated with a health benefit – protection against African sleeping sickness, a potentially lethal parasitic infection transmitted by the tsetse fly, found only in sub-Saharan Africa. However, people with two copies of the variant are at a higher risk for kidney disease.
The current research expands on these prior findings and demonstrates the effect of these variants on the progression of established kidney disease and development of end-stage renal disease; analyses their role in black-versus-white renal disease disparities; investigates their effect in patients with diabetes and observes the impact of blood pressure control on APOL1-associated disease progression.
According to Dr. Parsa, approximately 13 percent of the African American population has two copies of the risk variants. Fortunately, most of those at risk do not develop kidney disease. The researchers analysed the role of APOL1 gene variants in two longitudinal studies of patients with kidney disease: the Chronic Renal Insufficiency Cohort (CRIC) and the African American Study of Kidney Disease and Hypertension (AASK), both sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health (NIH). Dr. Parsa examined the CRIC study data, while co-lead author and Johns Hopkins epidemiologist W.H. Linda Kao, Ph.D., M.H.S., analysed the AASK data. University of Maryland Medical Center