Research into possible links between specific genetic variants and kidney disease in African-Americans failed to justify widespread screening in this population for such variants, because they do not appear to be a leading reason as to why blacks are at greater risk of kidney failure than whites.
The study, “Race, APOL1 Risk, and eGFR Decline in the General Population,” was published in the Journal of the American Society of Nephrology (JASN).
Evidence has shown that the elevated risk for chronic kidney disease in African-Americans is tied to genetic variation in the apolipoprotein L1 (APOL1), a protein encoded by the APOL1 gene in humans. Specifically, the APOL high-risk genotype, present in about 13 percent of African-Americans, is a risk factor for kidney function decline in people with CKD.
Morgan Grams from the Department of Medicine, Johns Hopkins University School of Medicine, and colleagues investigated people enrolled in the Atherosclerosis Risk in Communities (ARIC) study to understand how the genetic variants in APOL1 affect kidney disease and other aspects of health over time. A total of 15,140 people were followed from 1987–89 through to 2011–13. Of these, 75.3 percent were white, 21.5 percent were black/APOL1 low-risk, and 3.2 percent were black/APOL1 high-risk.
“Our study is a population-based cohort following participants over 25 years and thus well suited at assessing a fairly comprehensive set of outcomes among people with the high-risk genotype,” Dr. Grams said in a news release.
The researchers found that blacks were at an elevated risk for all assessed unfavorable health events — including kidney injury, kidney failure, hypertension, diabetes, and cardiovascular disease — when differences in demographic variables were assessed. However, when the researchers adjusted statistical analyses for socioeconomic status and comorbid diseases, results revealed that blacks were at elevated risk solely for diabetes, hypertension, and end-stage renal diseases (ESRD).
Among black participants, the APOL1 high-risk genotype was linked to an increased risk for ESRD, but results showed high variability in kidney function decline among those with and without the genetic variants.
“We found great variability in kidney function trajectory, such that most African Americans with the high-risk genotype experienced similar decline as African Americans with the low-risk genotype,” Dr. Grams said. “We did find pervasive racial disparities in adverse health outcomes not explained by the APOL1 risk variants, which suggests that interventions to improve health and health outcomes in African Americans are needed.”