thalassaemia Definition

any of a group of inherited hypochromic anemias and especially Cooley's anemia controlled by a series of allelic genes that cause reduction in or failure of synthesis of one of the globin chains making up hemoglobin and that tend to occur especially in individuals of Mediterranean, African, or southeastern Asian ancestry —sometimes used with a prefix (as alpha-, beta-, or delta-) to indicate the hemoglobin chain affected—called also Mediterranean anemia

thalassemia in which the hemoglobin chains designated beta are affected and which comprises Cooley's anemia in the homozygous condition and thalassemia minor in the heterozygous condition