Vitamin-D-Binding Protein in the Williams Syndrome and Idiopathic Hypercalcemia

Abstract

To the Editor: We have investigated the role of the vitamin-D-binding protein (group-specific component, Gc)¹ in the cause of two disorders of calcium metabolism.The Williams syndrome (WS) is a congenital disorder characterized by mental and mild growth deficiency, "elfin" facies, supravalvular aortic stenosis and, occasionally, elevated blood calcium. Epidemiologic and anecdotal evidence suggests that WS may be associated with hypersensitivity to vitamin D or excess ingestion of the vitamin during pregnancy.^{2 , 3} Also, vitamin D given in large doses to pregnant rabbits crosses the placenta and produces fetal lesions similar to human supravalvular aortic stenosis,⁴ and craniofacial and dental abnormalities . . .