title: A possible genetic defect in 25-hydroxylation as a cause of rickets.
abstract: We examined two siblings who had severe rickets at ages 2 and 7 years, respectively, despite a history of adequate vitamin D intake. The patients' sera had calcium concentrations at the lower limits of normal, low phosphate concentrations, elevated alkaline phosphatase activity, and low levels of 25-hydroxyvitamin D. Treatment with high doses of vitamin D2 resulted in resolution of the biochemical abnormalities and radiographic deformities; pharmacologic doses of vitamin D2 were required to maintain normal concentrations of 25-hydroxyvitamin D in the serum even though vitamin D absorption was normal. These children may have a genetic defect of the 25-hydroxylation step in vitamin D activation.
authors.affiliation: Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: S J
authors.initials: SJ
authors.lastname: Casella
authors.forename: B J
authors.initials: BJ
authors.lastname: Reiner
authors.forename: T C
authors.initials: TC
authors.lastname: Chen
authors.forename: M F
authors.initials: MF
authors.lastname: Holick
authors.forename: H E
authors.initials: HE
authors.lastname: Harrison
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D006801:Humans; D006900:Hydroxylation; D012279:Rickets / Q000235:genetics* / Q000378:metabolism*; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D014807:Vitamin D; D015652:25-Hydroxyvitamin D 2