Beta-thalassemia (BT) major is a severe early-onset form of BT characterized by severe anemia requiring regular red blood cell transfusions. The disease is beta-thalassemia major (MONDO_0016486). Also known as: Beta thalassemia Major, Cooley anaemia, Cooley anemia, Cooley's Anaemia, Cooley's Anemia, Mediterranean anaemia, Mediterranean anemia.