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 disorder. 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.

The symptoms of thalassemia can vary. Some of the most common ones include:

bone deformities, especially in the face

dark urine

delayed growth and development

excessive tiredness and fatigue

yellow or pale skin

Not everyone has visible symptoms of thalassemia. Signs of the disorder also tend to show up later in childhood or adolescence.