Mutations in the uromodulin/Tamm-Horsfall protein coding UMOD gene located within the critical interval of FJHN and MCKD2 at 16p11.2-12 were recently identified in FJHN and MCKD2 families [10], therefore providing definite evidence that MCKD and FJHN are allelic disorders. The gene discussed is UMOD; the disease is autosomal dominant medullary cystic kidney disease with or without hyperuricemia.