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Clinical and biochemical findings in parents of children with vitamin D‐dependent rickets type II
Author(s) -
Yokota I.,
Takeda E.,
Ito M.,
Kobashi H.,
Saijo T.,
Kuroda Y.
Publication year - 1991
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01800596
Subject(s) - rickets , human genetics , medicine , vitamin d and neurology , pediatrics , vitamin , endocrinology , biology , genetics , gene
Summary Vitamin D‐dependent rickets type II is a rare disease caused by a disorder of the receptor for 1, 25‐dihydroxyvitamin D (1, 25(OH) 2 D). Several parameters of this receptor‐effector system were investigated to obtain biochemical information on the presumed heterozygotes of vitamin D‐dependent rickets type II in parents of five patients and in their age‐matched controls. It was found that the serum concentrations of 1,25‐(OH) 2 D and 24,25‐dihydroxy‐vitamin D (24, 25(OH) 2 D), and the ratio of 1,25‐(OH) 2 D/24,25‐(OH) 2 D differed significantly in the parents from those of the patients and the respective control groups. In the parents' cultured skin fibroblasts, the activity of 25‐hydroxyvitamin D‐24‐hydroxylase induced by 10 −8 mol/L 1, 25‐(OH) 2 D 3 ranged from 50 to 82% of that of their controls (versus 1–13% of controls for the patients). The binding capacity of the parents' [ 3 H]1, 25‐(OH) 2 D 3 to the nucleus was 38–54% of that of their control subjects (versus 7–27% of controls for the patients). The parents' values were thus in a range between those of the patients and the control groups. These findings suggest that, in the parents, a partial impairment of the receptor system for 1,25‐(OH) 2 D led to an imbalance of vitamin D metabolism, thus confirming that vitamin D‐dependent rickets type II is an autosomal recessive inherited disease. Serum concentrations of 1, 25‐(OH) 2 D and 24,25‐(OH) 2 D may provide useful parameters for detecting heterozygotes of this disease.