A photograph of Albert Johan Kramer, a giant, holding Fred Aslett, a dwarf. Kramer is 8 ft 9 3/4 inches; Aslett is 2ft 4 inches. The woman and man are of normal height. Gigantism is a rare disorder resulting from increased levels of growth hormone before the fusion of the growth plate, which usually occurs at some point soon after puberty. This increase is most often due to abnormal tumor growths on the pituitary gland. Dwarfism can result from many medical conditions, each with its own separate symptoms and causes. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth-hormone deficiency, once called pituitary dwarfism. Two disorders, achondroplasia and growth hormone deficiency, are responsible for the majority of human dwarfism cases.