The Uromodulin (UMOD) gene encodes the Tamm-Horsfall protein (which is the most abundant physiological urinary protein in humans [99,100] produced by renal tubular cells of the distal loop of Henle) and its mutations have been linked to the pathogenesis of familial juvenile hyperuricemic nephropathy (FJHN), glomerulocystic kidney disease (GCKD) and autosomal dominant medullary cystic kidney disease 2 (MCKD2) [33,101]. The gene discussed is UMOD; the disease is familial juvenile hyperuricemic nephropathy type 1.