Vitamin D-dependent rickets type I and type II

Acta Paediatr Jpn. 1997 Aug;39(4):508-13. doi: 10.1111/j.1442-200x.1997.tb03629.x.


Two distinct hereditary defects, vitamin D-dependent rickets type I (VDDR I) and type II (VDDR II), have been recognized in vitamin D metabolism. VDDR I is suggested to be a deficiency of the renal 25-hydroxyvitamin D (25(OH)D)-1 alpha-hydroxylase. Muscle weakness and rickets are the prominent clinical findings. A normal physiologic dose of 1 alpha-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 is sufficient to maintain remission of rickets in this disorder. VDDR II consists of a spectrum of intracellular vitamin D receptor (VDR) defects and is characterized by the early onset of severe rickets and associated alopecia. This can be attributed to mutations in the VDR gene. Massive doses of vitamin D analogs and calcium supplementation is usually required for the treatment; however, the response to therapy is sometimes variable.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase / deficiency
  • Calcifediol / pharmacology
  • Calcifediol / therapeutic use
  • Calcitriol / pharmacology
  • Calcitriol / therapeutic use
  • Gene Expression Regulation, Enzymologic
  • Humans
  • Receptors, Calcitriol / genetics
  • Rickets / diagnosis
  • Rickets / genetics*
  • Rickets / physiopathology
  • Rickets / therapy


  • Receptors, Calcitriol
  • 25-Hydroxyvitamin D3 1-alpha-Hydroxylase
  • Calcitriol
  • Calcifediol