Do you pursue genetic testing in a patient with unexplained CKD whose kidney biopsy shows nonspecific tubulointerstitial nephritis without an identifiable toxic, inflammatory, or systemic cause?

Yes. I have seen some interesting diagnoses such as ADTKD. Genetic testing is simple, non-invasive, and relatively inexpensive. I am all for doing more of it.

I generally do; I see little downside and have found some surprises, eg one patient had both 2 high risk APOL-1 genotypes and a COL4A3 mutation. I am also ordering it on non-nephrotic FSGS, also finding several COL4A # -4 mutations.

Yes. Genetic testing is indicated in a patient with unexplained CKD whose kidney biopsy shows nonspecific tubulointerstitial nephritis without an identifiable toxic, inflammatory, or systemic cause. If the patient has hyperuricemia and early-onset gout, a mutation in the UMOD gene encoding uromodulin needs to be excluded. If the patient has early-onset anemia, hypotension, and hyperkalemia, a mutation in the REN gene encoding renin should be considered. Mutations in the MUC1 gene encoding mucin-1 are also associated with progressive CKD due to tubulointerstitial kidney disease. Confirmation of a genetic diagnosis may prevent the unnecessary use of immunosuppressive therapies (e.g., steroids) for treatment of interstitial nephritis. It is al...

I discuss pros and cons with the patient. Generally, not much upside, but willing to refer if the patient is interested.