Thalassemia is an inherited blood disorder in which the body makes an abnormal form of hemoglobin. Hemoglobin is the protein molecule in red blood cells that carries oxygen.The disorder results in excessive destruction of red blood cells, which leads to anemia. Anemia is a condition in which your body doesn’t have enough normal, healthy red blood cells.Thalassemia is inherited, meaning that at least one of your parents must be a carrier of the disease. It’s caused by either a genetic mutation or a deletion of certain key gene fragments.Thalassemia minor is a less serious form of the disorder. There are two main forms of thalassemia that are more serious. In alpha thalassemia, at least one of the alpha globin genes has a mutation or abnormality. In beta thalassemia, the beta globin genes are affected.Each of these forms of thalassemia has different subtypes. The exact form you have will affect the severity of your symptoms and your outlook.