[Vitamin D receptor and its abnormality in human diseases]

The vitamin D receptor(VDR) belongs to the nuclear hormone receptor super-family, and modulates the transcription of target genes in response to 1,25-dihydroxyvitamin D3[1,25(OH)2D3]. The discovery of the cDNA for the human VDR revealed that the VDR contains 427 or 424 amino acids because it has two initiation sites. The human VDR gene has 8 coding exons and 3 alternative 5' noncoding exons spanning over 75 kb of DNA on chromosome 12. Vitamin D-dependent rickets type II is associated with the abnormality of the VDR function, leading to target organ resistance to 1,25(OH)2D3. This autosomal recessive disease is characterized by hypocalcemia, rickets and alopecia. VDR gene knock-out has been created in mice by two groups, providing animal model for the disease.