The inherited rare kidney stone disorders studied by the RKSC include cystinuria, primary hyperoxaluria, adenine phosphoribosyltransferase (APRT) deficiency, and Dent disease (see Table 1).
All children with reduced kidney function with or without stone disease should undergo metabolic screening for cystinuria, primary hyperoxaluria, APRT deficiency, and Dent disease (Edvardsson et al.
Dent disease is a very rare X-linked disorder of proximal tubule dysfunction due to mutations in the CLCN5 chloride/protein exchanger gene (Dent disease 1, accounting for 60% of cases) or in the OCRL1 gene (Dent disease 2, accounting for 15% of cases) (Devuyst & Thakker, 2010; Edvardsson et al.
Dent disease is characterized by low-molecular-weight (LMW) proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure (Devuyst & Thakker, 2010; Lieske et al.
Dent disease generally presents in childhood or early adulthood, with males more severely affected than females.
Clinical diagnosis of Dent disease is based on the presence of all three of the following criteria: a) LMW proteinuria (elevation of urinary excretion of 2microglobulin or retinol binding protein (RBP) by at least 5-fold above the upper limit of normality); b) hypercalciuria (> 4 mg/kg in a 24 h-hour collection or > 0.
Some patients with Dent disease not only have LMW proteinuria, but albuminuria as well; occasionally, they may present with the nephrotic syndrome.