Beta thalassemia is a blood disorder that reduces the production of hemoglobin. Hemoglobin is the iron-containing protein in red blood cells that carries oxygen to cells throughout the body. In people with beta thalassemia, low levels of hemoglobin lead to a lack of oxygen in many parts of the body.
Thalassemia is caused by variant or missing genes that affect how the body makes hemoglobin, the protein in red blood cells that carries oxygen. People with thalassemia make less hemoglobin and have fewer circulating red blood cells than normal, which results in mild or severe anemia.
There are two main types of thalassemia: Alpha thalassemia occurs when a gene or genes related to the alpha globin protein are missing or changed (mutated). Beta thalassemia occurs when similar gene defects affect production of the beta globin protein.