A disorder that is caused by the deficiency of a vitamin. The deficiency may result from either suboptimal vitamin intake or conditions that prevent the vitamin's use or absorption in the body. Representative examples include beriberi caused by thiamine deficiency, scurvy caused by vitamin C deficiency, and rickets caused by vitamin D deficiency. The disease is MONDO_0024298 (vitamin deficiency disorder). Also known as: avitaminosis, vitamin deficiency.