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Endocrinol Metab Clin North Am. 2010 Jun;39(2):333-46, table of contents. doi: 10.1016/j.ecl.2010.02.004.

Genetic disorders and defects in vitamin d action.

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Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford University, S-025 Endocrinology, Stanford, CA 94305-5103, USA.


Two rare genetic diseases can cause rickets in children. The critical enzyme to synthesize calcitriol from 25-hydroxyvitamin D, the circulating hormone precursor, is 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase). When this enzyme is defective and calcitriol can no longer be synthesized, the disease 1alpha-hydroxylase deficiency develops. The disease is also known as vitamin D-dependent rickets type 1 or pseudovitamin D deficiency rickets. When the VDR is defective, the disease hereditary vitamin D-resistant rickets, also known as vitamin D-dependent rickets type 2, develops. Both diseases are rare autosomal recessive disorders characterized by hypocalcemia, secondary hyperparathyroidism, and early onset severe rickets. In this article, these 2 genetic childhood diseases, which present similarly with hypocalcemia and rickets in infancy, are discussed and compared.

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