An article in the New England Journal of Medicine (Volume 394, Issue 8, Pages 809-810, February 19, 2026) discusses gene therapy for nephropathic cystinosis. Nephropathic cystinosis is a monogenic disease caused by a mutation in one gene.[1] Gene therapy provides a functional copy of the defective gene using an inactivated adeno-associated virus (AAV).[1] This approach repairs defective DNA in kidney cells and other tissues.[1] The study reports the main findings from a clinical trial where patients showed improvement in kidney function after the therapy.[3] In Slovakia, it is diagnosed in eight children and one patient was identified in infancy.[3] The therapy represents an advance over current supportive treatment.[3]