Activity of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase in a case of X-linked hypophosphataemic rickets. 1984

Y Seino, and K Satomura, and K Yamaoka, and Y Tanaka, and H Tanaka, and T Yamamoto, and M Ishida, and H Yabuuchi

In 1974, a 2-year-old boy was diagnosed as having X-linked hypophosphataemic rickets (XLH) because of severe rickets and hypophosphataemia. The vitamin D metabolite concentrations, blood and urine chemistry and renal 25-hydroxyvitamin D3 (25OHD3)-1 alpha-hydroxylase were measured in 1982 (about 2 weeks after withdrawal of medication). 1 alpha-hydroxylase was 392 pg/mg tissue/20 min in the patient, which was high compared with aged-matched controls (69.7 +/- 28.5 pg/mg tissue/20 min, mean +/- SD, n = 7). Our present studies showed that the 1 alpha-hydroxylase activity in the patient with XLH was elevated. Therefore, the normal or low 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) concentrations in XLH patients could be due to accelerated catabolism of 1,25-(OH)2D3 or abnormally regulated 25OHD3-1 alpha-hydroxylase in response to hypophosphataemia, although significantly elevated above that in normal controls.

UI MeSH Term Description Entries
D007015 Hypophosphatemia, Familial An inherited condition of abnormally low serum levels of PHOSPHATES (below 1 mg/liter) which can occur in a number of genetic diseases with defective reabsorption of inorganic phosphorus by the PROXIMAL RENAL TUBULES. This leads to phosphaturia, HYPOPHOSPHATEMIA, and disturbances of cellular and organ functions such as those in X-LINKED HYPOPHOSPHATEMIC RICKETS; OSTEOMALACIA; and FANCONI SYNDROME. Diabetes, Phosphate,Familial Hypophosphatemia,Hyperphosphaturia,Phosphate Diabetes,Phosphaturia,Familial Hypophosphatemias,Hypophosphatemias, Familial
D007668 Kidney Body organ that filters blood for the secretion of URINE and that regulates ion concentrations. Kidneys
D008297 Male Males
D002675 Child, Preschool A child between the ages of 2 and 5. Children, Preschool,Preschool Child,Preschool Children
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012279 Rickets Disorders caused by interruption of BONE MINERALIZATION manifesting as OSTEOMALACIA in adults and characteristic deformities in infancy and childhood due to disturbances in normal BONE FORMATION. The mineralization process may be interrupted by disruption of VITAMIN D; PHOSPHORUS; or CALCIUM homeostasis, resulting from dietary deficiencies, or acquired, or inherited metabolic, or hormonal disturbances. Rachitis,Rachitides
D013250 Steroid Hydroxylases Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism. Steroid Hydroxylase,Steroid Monooxygenases,Hydroxylase, Steroid,Hydroxylases, Steroid,Monooxygenases, Steroid
D015090 25-Hydroxyvitamin D3 1-alpha-Hydroxylase A mitochondrial cytochrome P450 enzyme that catalyzes the 1-alpha-hydroxylation of 25-hydroxyvitamin D3 (also known as 25-hydroxycholecalciferol) in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP27B1 gene, converts 25-hydroxyvitamin D3 to 1-alpha,25-dihydroxyvitamin D3 which is the active form of VITAMIN D in regulating bone growth and calcium metabolism. This enzyme is also active on plant 25-hydroxyvitamin D2 (ergocalciferol). 25-Hydroxycholecalciferol 1-Hydroxylase,CYP27B1,Calcidiol 1-Monooxygenase,Cytochrome P-450 CYP27B1,25-Hydroxycholecalciferol-1-Hydroxylase,25-Hydroxyergocalciferol 1-alpha-Hydroxylase,25-Hydroxyvitamin D 1-alpha-Hydroxylase,25-Hydroxyvitamin D(3) 1 alpha-Hydroxylase,25-Hydroxyvitamin D2 1-hydroxylase,1-alpha-Hydroxylase, 25-Hydroxyergocalciferol,1-alpha-Hydroxylase, 25-Hydroxyvitamin D,1-hydroxylase, 25-Hydroxyvitamin D2,25 Hydroxycholecalciferol 1 Hydroxylase,25 Hydroxyergocalciferol 1 alpha Hydroxylase,25 Hydroxyvitamin D 1 alpha Hydroxylase,25 Hydroxyvitamin D2 1 hydroxylase,25 Hydroxyvitamin D3 1 alpha Hydroxylase,Calcidiol 1 Monooxygenase,Cytochrome P 450 CYP27B1

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