Disease Information for Familial Vitamin D dependent Rickets: Definition

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  • Vitamin D dependent rickets; Normo-phosphatemic hereditary disorder; Not sexlinked; type I below: ------------------------HEREDITARY VITAMIN D-DEPENDENT RICKETS

    Type I (pseudo-vitamin D deficiency) is an autosomal recessive syndrome, characterized by severe rickets, normal 25(OH)D3 and subnormal 1,25(OH)2D3 plasma levels, low or normal serum calcium, hypophosphatemia, and generalized aminoaciduria; This disorder results from absent or defective 1 -hydroxylase in the kidneys and responds to physiologic quantities of 1,25(OH)2D3 (1 to 2 µg/day) IV or po; Type II exists in several forms and is due to mutations in the 1,25(OH)2D3 receptor; This receptor, which is a transcription factor for 1,25(OH)2D3, causes expression of a variety of genes that control the metabolism of gut, kidney, bone, and other cells; The lack of a functional receptor produces a high but ineffective level of 1,25(OH)2D3; Some patients respond to very high doses of 1,25(OH)2D3 (10 to 40 µg/day); others do not respond at all-----------[Merck Manual 17th]--------------------------

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