Familial hypomagnesemia with hypercalciuria and nephrocalcinosis is a progressive renal disorder characterized by excessive urinary Ca(2+) and Mg(2+) excretion. There is progressive loss of kidney function, and in about 50% of cases, the need for renal replacement therapy arises as early as the second decade of life (summary by Muller et al., 2006). Amelogenesis imperfecta may also be present in some patients (Bardet et al., 2016). A similar disorder with renal magnesium wasting, renal failure, and nephrocalcinosis (HOMG5; 248190) is caused by mutations in another tight-junction gene, CLDN19 (610036), and is distinguished by the association of severe ocular involvement. For a discussion of phenotypic and genetic heterogeneity of familial hypomagnesemia, see HOMG1 (602014).

Calcium oxalate nephrolithiasis-2 with or without nephrocalcinosis (CAON2) is an autosomal dominant disorder of renal function characterized by the recurrent formation of CaOx kidney stones. The age at onset is highly variable, ranging from childhood to adult. Most affected individuals have concurrent nephrocalcinosis. Renal function is generally preserved (Majmundar et al., 2023). See also CAON1 (167030).