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Acta Paediatr Jpn. 1997 Aug;39(4):508-13.

Vitamin D-dependent rickets type I and type II.

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Department of Clinical Nutrition, School of Medicine, University of Tokushima, Japan.


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.

[Indexed for MEDLINE]

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