A person with two such genes has severe, transfusion-dependent thalassemia, called thalassemia major . Often, the thalassemia genes produce some beta globin protein, but the amount is reduced. Two such genes can sometimes together produce enough beta globin protein so that the patient does not require chronic transfusions to live. This condition is thalassemia intermedia . Thalassemia intermedia is defined clinically by the transfusion requirement of the patient.
Many considerations go into the decision to transfuse a patient chronically.
Therefore, a person can change clinically from thalassemia intermedia to thalassemia major at some point during their life, while no chance occurs in their genetic makeup. Alpha Thalassemia Alpha thalassemia develops because one or more of the four alpha globin genes fail to produce alpha globin protein. The inheritance of alpha thalassemia is complex because each parent potentially passes two of their four alpha globin genes to the offspring. One aspect of the inheritance that simplifies predictions is that alpha genes are on the the same chromsosome and are inherited as pairs . The key issue is whether two alpha genes on the same chromosome are deleted.