Korean J Pediatr.  2011 Feb;54(2):51-54. 10.3345/kjp.2011.54.2.51.

Vitamin D dependent rickets type I

• Kim CJ

• KMID: 2073621
• DOI: http://doi.org/10.3345/kjp.2011.54.2.51

Abstract

Vitamin D is present in two forms, ergocalciferol (vitamin D2) produced by plants and cholecalciferol (vitamin D3) produced by animal tissues or by the action of ultraviolet light on 7-dehydrocholesterol in human skin. Both forms of vitamin D are biologically inactive pro-hormones that must undergo sequential hydroxylations in the liver and the kidney before they can bind to and activate the vitamin D receptor. The hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D], plays an essential role in calcium and phosphate metabolism, bone growth, and cellular differentiation. Renal synthesis of 1,25(OH)2D from its endogenous precursor, 25-hydroxyvitamin D (25OHD), is the rate-limiting and is catalyzed by the 1alpha-hydroxylase. Vitamin D dependent rickets type I (VDDR-I), also referred to as vitamin D 1alpha-hydroxylase deficiency or pseudovitamin D deficiency rickets, is an autosomal recessive disorder characterized clinically by hypotonia, muscle weakness, growth failure, hypocalcemic seizures in early infancy, and radiographic findings of rickets. Characteristic laboratory features are hypocalcemia, increased serum concentrations of parathyroid hormone (PTH), and low or undetectable serum concentrations of 1,25(OH)2D despite normal or increased concentrations of 25OHD. Recent advances have showed in the cloning of the human 1alpha-hydroxylase and revealed mutations in its gene that cause VDDR-I. This review presents the biology of vitamin D, and 1alpha-hydroxylase mutations with clinical findings.

Keyword

Vitamin D; Rickets; 1alpha-hydroxylase

MeSH Terms

Animals
Biology
Bone Development
Calcitriol
Calcium
Cholecalciferol
Clone Cells
Cloning, Organism
Dehydrocholesterols
Ergocalciferols
Humans
Hydroxylation
Hypocalcemia
Kidney
Liver
Muscle Hypotonia
Parathyroid Hormone
Receptors, Calcitriol
Rickets
Seizures
Skin
Ultraviolet Rays
Vitamin D
Vitamins
Calcitriol
Calcium
Cholecalciferol
Dehydrocholesterols
Ergocalciferols
Parathyroid Hormone
Receptors, Calcitriol
Vitamin D
Vitamins