What is Beta Thalassemia?
Beta thalassemia is a rare inherited blood disorder caused by a defect in the adult type of hemoglobin in red blood cells. Hemoglobin carries oxygen to all tissues and organs in the body, including the heart, brain, lungs and kidneys. In people with beta thalassemia, the defect is caused by a mutation in the gene responsible for making beta globin, a vital part of the oxygen-carrying adult type hemoglobin complex in the red blood cells. The mutation causes the body to make fewer healthy red blood cells, leading to life-threatening anemia, enlarged spleen, liver and heart problems, and bone abnormalities. As a result, people with beta thalassemia require frequent blood transfusions. However, these transfusions can cause iron overload, which can further damage organs in the body. To get rid of the excess iron, lifelong iron chelation therapy is needed.
Beta thalassemia occurs at different levels of severity. People with the most severe form require frequent blood transfusions, as well as iron chelation therapy, for life. Both of these procedures, along with the effects of anemia and iron overload, can have a debilitating impact on a person's quality of life.
Currently, there is only one proven cure for beta thalassemia: blood stem cell transplant, also known as bone marrow transplant. “Allogenic” transplants include a transplantation of normal blood stem cells from a healthy donor after chemotherapy is administered to the patient to make room in the bone marrow for the donor’s cells to engraft. Due to genetic differences between the donor and the patient, allogeneic bone marrow transplants carry a substantial risk of complications. One such complication is graft rejection, which is when the patient’s immune system rejects the foreign donor cells. Another complication is graft-versus-host disease which occurs when the donor cells regard the recipient’s body as foreign and as a result attack the patient’s tissues and organs. These complications can cause chronic morbidity or even death. In order to minimize the risks of complications in allogeneic bone marrow transplantation, doctors search for genetically well-matched donors. However, it can be extremely difficult to find a well-matched related or unrelated donor. Among other things, the likelihood of finding a sufficiently matched donor is influenced by the ethnicity of the recipient. For example, only about 1 out of 5 people with beta thalassemia of African descent are likely to find a suitable donor match. This means that this potential curative treatment is not available to many people living with beta thalassemia.
In the absence of allogeneic bone marrow transplant, the treatment plan for people living with severe forms of beta thalassemia currently consists of a life-long supportive care regimen of chronic transfusions and iron chelation therapy to improve life expectancy and quality of life. For the few people with beta thalassemia who are eligible for allogeneic blood stem cell transplants, there is the risk of potentially chronic and even fatal complications. This shows an urgent need for new treatment options for beta thalassemia.