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[Vitamin D dependency and vitamin D resistance]
1Department of Clinico-Pathological Nutrition, School of Medicine, University of Tokushima.
Nihon Rinsho. Japanese Journal of Clinical Medicine
|April 1, 1993
Summary
Vitamin D dependency disorders, including rickets types I and II, stem from genetic defects in vitamin D metabolism or receptor function. Vitamin D resistance involves phosphate transport issues, with underlying causes still under investigation.
Area of Science:
- Biochemistry
- Genetics
- Pediatrics
Context:
- Vitamin D metabolism and action are crucial for calcium-phosphate homeostasis.
- Genetic defects can lead to distinct clinical presentations of rickets and vitamin D resistance.
Purpose:
- To differentiate between vitamin D dependency and vitamin D resistance based on their underlying genetic and metabolic defects.
- To outline the known genetic causes of vitamin D-dependent rickets types I and II.
- To introduce the clinical entities associated with vitamin D resistance and phosphate transport disorders.
Summary:
- Vitamin D dependency rickets results from genetic defects in 25-hydroxyvitamin D-1 alpha-hydroxylase (Type I) or the vitamin D receptor (Type II).
- Vitamin D resistance is characterized by hypophosphatemia due to impaired renal phosphate transport, encompassing hereditary hypophosphatemic rickets with hypercalciuria, familial hypophosphatemic rickets, and oncogenic hypophosphatemic osteomalacia.
- The precise pathogenesis of vitamin D resistance disorders remains incompletely understood.
Impact:
- Clarifies the genetic basis of distinct vitamin D-related bone disorders.
- Highlights the need for further research into the pathogenesis of vitamin D resistance.
- Provides a framework for understanding and potentially diagnosing these rare genetic conditions.