Thalassemias (thal-a-SE-me-ahs) are inherited blood disorders. "Inherited" means that the disorder is passed from parents to children through genes.
Thalassemias cause the body to make fewer healthy red blood cells and less hemoglobin (HEE-muh-glow-bin) than normal. Hemoglobin is an iron-rich protein in red blood cells. It carries oxygen to all parts of the body. Hemoglobin also carries carbon dioxide (a waste gas) from the body to the lungs, where it's exhaled.
People who have thalassemias can have mild or severe anemia (uh-NEE-me-uh). Anemia is caused by a lower than normal number of red blood cells or not enough hemoglobin
