title: Medullary nephrocalcinosis in an adult patient with idiopathic infantile hypercalcaemia and a novel CYP24A1 mutation.
abstract: Idiopathic infantile hypercalcaemia (IIH) is an autosomal recessively inherited disease, presented in the first year of life with hypercalcaemia, precipitated by normal amounts of vitamin D supplementation. Recently loss-of-function mutations in the CYP24A1 gene, which encodes the vitamin D-metabolizing enzyme 24-hydroxylase, have been found in these patients. We describe a young man homozygous for a novel missense mutation (c.628T>C) of the CYP24A1 gene. He had suffered from severe hypercalcaemia in early childhood. At age 29 he presented with medullary nephrocalcinosis, chronic kidney disease (CKD) stage 2, microalbuminuria, mild hypertension and nephrogenic diabetes insipidus. He had mild hypercalcaemia and moderate hypercalciuria. As a novel finding, fibroblast growth factor 23 (FGF23) was elevated.
authors.affiliation: Department of Nephrology and Dialysis , Academic Teaching Hospital Feldkirch , Feldkirch , Austria.
authors.forename: Edgar
authors.initials: E
authors.lastname: Meusburger
authors.forename: Axel
authors.initials: A
authors.lastname: Mündlein
authors.forename: Emanuel
authors.initials: E
authors.lastname: Zitt
authors.forename: Barbara
authors.initials: B
authors.lastname: Obermayer-Pietsch
authors.forename: Dieter
authors.initials: D
authors.lastname: Kotzot
authors.forename: Karl
authors.initials: K
authors.lastname: Lhotta
keywords: fibroblast growth factor 23; hypercalcaemia; nephrocalcinosis