Vitamin D resistance

This review will discuss the syndrome of hereditary hypocalcemic rickets due to generalized resistance to the action of the active vitamin D hormone, 1α,25-dihydroxyvitamin D. Historically, this entity usually has been refered to as “vitamin D–dependent rickets, type II” (VDDR II). However, now that the biochemical basis of the disease is understood, we prefer the terminology “hereditary vitamin D–resistant rickets” (HVDRR). In order to describe the syndrome of HVDRR, we will first briefly discuss the vitamin D endocrine system, the mechanism of action of 1,25(OH)2D, and the nature of the vitamin D receptor (VDR). After this background is presented, we will then portray the syndrome of HVDRR and detail the heterogeneous mutations in the VDR that cause the vitamin D–resistant state. Various aspects of vitamin D metabolism and action as well as the syndrome of HVDRR recently have been reviewed in the volume entitled Vitamin D( 1 Feldman D Glorieux F.H Pike J.W Vitamin D. Academic Press, San Diego1997 Google Scholar ).