We describe one patient with the pre-symptomatic diagnosis of the disease named afamilial nephropathy associated to hyperuricemia)) (OMIM 162000; FJHN). This is a hereditary disease, autosomic dominant, characterized by its progression to renal insufficiency. Several mutations in the gene that codifies uromodulin or Tannn-Horsfall protein (UMOD) have been identified in some families. The clinical presentation is heterogeneous. In some cases the disease appears as juvenile hyperuricemia due to a diminished renal urate excretion, with or without gout, but in some other cases the first manifestation is renal insuffciency. The study of the UMOD gene shows that patient is heterozygous for the mutation C869 --> A, which results in C255Y change, and enabled to establish the diagnosis of FJHN. This patient shows the possibility to identify the genetic alteration associated to FJHN in early stages. This fact implies a clinical follow-up and eventual treatment to reduce the inexorable progression to renal insuffciency.