A new consensus statement recommended genetic testing for all categories of kidney diseases whenever a genetic cause is suspected and offered guidance on who to test, which tests are the most useful, and how to talk to patients about results.
The statement, published online in the American Journal of Kidney Diseases, is the work of four dozen authors — including patients, nephrologists, experts in clinical and laboratory genetics, kidney pathology, genetic counseling, and ethics. The experts were brought together by the National Kidney Foundation (NKF) with the goal of broadening use and understanding of the tests.
About 10% or more of kidney diseases in adults and 70% of selected chronic kidney diseases (CKDs) in children have genetic causes. But nephrologists have reported a lack of education about genetic testing, and other barriers to wider use, including limited access to testing, cost, insurance coverage, and a small number of genetic counselors who are versed in kidney genetics.
Genetic testing “in the kidney field is a little less developed than in other fields,” said co–lead author Nora Franceschini, MD, MPH, a professor of epidemiology at the University of North Carolina Gillings School of Global Public Health, Chapel Hill, and a nephrologist who studies the genetic epidemiology of hypertension and kidney and cardiovascular diseases.
There are already many known variants that play a role in various kidney diseases and more are on the horizon, Dr. Franceschini told this news organization. More genetic tests will be available in the near future. “The workforce needs to be prepared,” she said.
The statement is an initial step that gets clinicians thinking about testing in a more systematic way, said Dr. Franceschini. “Genetic testing is just another test that physicians can use to complete the story when evaluating patients.
“I think clinicians are ready to implement” testing, said Dr. Franceschini. “We just need to have better guidance.”
Who, When, What to Test
The NKF statement is not the first to try to address gaps in use and knowledge. A European Renal Association Working Group published guidelines in 2022.
The NKF Working Group came up with 56 recommendations and separate algorithms to guide testing for adult and pediatric individuals who are considered at-risk (and currently asymptomatic) and for those who already have clinical disease.
Testing can help determine a cause if there’s an atypical clinical presentation, and it can help avoid biopsies, said the group. Tests can also guide choice of therapy.
For at-risk individuals, there are two broad situations in which testing might be considered: In family members of a patient who already has kidney disease and in potential kidney donors. But testing at-risk children younger than 18 years should only be done if there is an intervention available that could prevent, treat, or slow progression of disease, said the authors.
For patients with an established genetic diagnosis, at-risk family members should be tested with the known single-gene variant diagnostic instead of a broad panel, said the group.
Single-gene variant testing is most appropriate in situations when clinical disease is already evident or when there is known genetic disease in the family, according to the NKF panel. A large diagnostic panel that covers the many common genetic causes of kidney disease is recommended for the majority of patients.
The group recommended that apolipoprotein L1 (APOL1) testing should be included in gene panels for CKD, and it should be offered to any patient “with clinical findings suggestive of APOL1-association nephropathy, regardless of race and ethnicity.”
High-risk APOL1 genotypes confer a 5- to 10-fold increased risk for CKD and are found in one out of seven individuals of African ancestry, which means the focus has largely been on testing those with that ancestry.
However, with many unknowns about APOL1, the NKF panel did not want to “profile” individuals and suggest that testing should not be based on skin color or race/ethnicity, said Dr. Franceschini.
In addition, only about 10% of those with the variant develop disease, so testing is not currently warranted for those who do not already have kidney disease, said the group.
They also recommended against the use of polygenic risk scores, saying that there are not enough data from diverse populations in genome-wide association studies for kidney disease or on their clinical utility.