Genetic disorders and defects in vitamin d action

• Published in: Endocrinology and metabolism clinics of North America Vol. 39; no. 2; p. 333
• Main Authors: Malloy, Peter J, Feldman, David
• Format: Journal Article
• Language: English
• Published: United States 01.06.2010
• Subjects: 25-Hydroxyvitamin D3 1-alpha-Hydroxylase - deficiency; 25-Hydroxyvitamin D3 1-alpha-Hydroxylase - genetics; Alopecia - genetics; Animals; Calcitriol - biosynthesis; Calcitriol - genetics; Calcitriol - therapeutic use; Child; Child, Preschool; Female; Humans; Hyperparathyroidism, Secondary - genetics; Hypocalcemia - genetics; Infant; Infant, Newborn; Male; Mice; Receptors, Calcitriol - genetics; Rickets - genetics; Rickets - metabolism; Rickets - pathology
• ISSN: 1558-4410
• DOI: 10.1016/j.ecl.2010.02.004

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.