Thalassemia is a blood disorder inherited from one or both parents. It is mostly inherited in an autosomal recessive pattern, although a rare variant that is dominantly inherited has been discovered. Both alpha and beta thalassemia can be inherited in either homozygous or heterozygous form.
Thalassemia specifically affects the genetic instructions we have for producing hemoglobin. When someone has thalassemia it actually means that part of the instructions for making hemoglobin are missing. This is known as a gene deletion. Alternatively, the genetic information for making Hb is incorrect and results in a reduced production. This is known as a gene mutation. Ironically, “having thalassemia” is a direct result of “not having” the right instructions to properly produce blood.
Hemoglobin is made of alpha and beta globin chains. Deletions or mutations (collectively known as mutations) of the instructions for making alpha globin chains cause alpha thalassemia and the mutations of the instructions for making beta globin chains cause beta thalassemia. These deletions cause a reduction or absence of the affected globin chains, which in turn causes the red blood cells to have a shorter lifespan. A shorter lifespan of blood cells means that your body is forced to produce more of it more frequently. In severe cases of thalassemia or other anemias the body cannot keep up production on its own. This is why severe cases generally require blood transfusions.
Blood is produced in the bone marrow. In severe thalassemia the bone marrow works very hard, resulting in expansion of the marrow and resulting deformities in the bone structure. This is why patients who are not on a regular transfusion schedule have very similar physical characteristics. In addition to visible changes to the body, severe thalassemia also causes damage to the internal organs. Iron is deposited in the organs from the rapid destruction of red blood cells and from the blood transfusion treatment. Special therapy is required to remove the blood because the complications from iron overload are hard to see until damage becomes irreversible.