Vitamin D-dependent rickets type I and type II.
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.
Takeda
E
E
Department of Clinical Nutrition, School of Medicine, University of Tokushima, Japan.
Yamamoto
H
H
Taketani
Y
Y
Miyamoto
K
K
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000172:deficiency; D002112:Calcifediol / Q000494:pharmacology / Q000627:therapeutic use; D002117:Calcitriol / Q000494:pharmacology / Q000627:therapeutic use; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D018167:Receptors, Calcitriol / Q000235:genetics; D012279:Rickets / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology / Q000628:therapy
D018167:Receptors, Calcitriol; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D002117:Calcitriol; D002112:Calcifediol