vitamin D-dependent rickets, type 1 (MONDO_0009924) can be described as follows. Hypocalcemic vitamin D-dependent rickets (VDDR-I) is an early-onset hereditary vitamin D metabolism disorder characterized by severe hypocalcemia leading to osteomalacia and rachitic bone deformations, and moderate hypophosphatemia. Also known as: 1 Alpha-hydroxylase deficiency, 1-alpha-hydroxylase deficiency, PDDRI, VDDI, VDDR-I, VDDR1, hypocalcemic vitamin D-dependent rickets, pseudo vitamin-D deficient rickets.