Beta Thalassemia (Cooley's Anemia)
What is beta thalassemia?
Thalassemia is an inherited disorder that affects the production of normal hemoglobin (a type of protein in red blood cells that carries oxygen to the tissues of the body). Thalassemia includes a number of different forms of anemia. The severity and type of anemia, including the beta thalassemias, depends on the number of genes that are affected.
Beta thalassemia is caused by mutations in the beta chain of the hemoglobin molecule. There is one beta chain gene on each #11 chromosome, for a total of two. How these genes are altered determines the specific type of beta thalassemia in a person:
- Beta thalassemia major (Cooley’s anemia)--both (two) beta chain genes have deletions, causing the most severe type of beta thalassemia. Thalassemia major patients need frequent blood transfusions and may not survive a normal lifespan. During the first one to two years of life, they can be pale, fussy, have a poor appetite, and have many infections. Without treatment, the spleen, liver, and heart become enlarged, and bones can become thin, brittle, and deformed. A major problem is the build up of iron in the heart and other organs, resulting in heart failure for some patients in their teens or early 20s.
- Thalassemia minor or thalassemia trait--one beta gene has a deletion, resulting in anemia. Thalassemia minor is further divided into categories dependent on the patient's presentation:
- Thalassemia minima--person has few or no symptoms.
- Thalassemia intermedia--person has moderate to severe anemia.
People with thalassemia minor have a 50/50 chance to pass the gene to their offspring, who would also have thalassemia minor. Many people are given iron replacement under the mistaken belief that their anemia is the iron-deficient type. Since too much iron can be harmful, it is important to demonstrate conclusively that a patient has iron deficiency before beginning treatment. If there is any question as to whether a patient has thalassemia, it is wise to consult a hematologist before beginning any treatment. Thalassemia major is inherited by an autosomal recessive gene, which means that two copies of the gene are necessary to produce the condition, one inherited from each of two carrier parents who have thalassemia minor.
How is beta thalassemia diagnosed?
Beta thalassemia is most often found in people who are of Mediterranean ancestry (Greek or Italian). Each child of two carrier parents is at 25 percent risk for the disease. Carrier status can be determined by the following:
- Complete blood count (CBC)--a measurement of size, number, and maturity of different blood cells in a specific volume of blood.
- Hemoglobin electrophoresis with hemoglobin F and A2 quantitation--a lab procedure that differentiates the types of hemoglobin present.
All of these studies can be performed from a single blood sample. Prenatal diagnosis is determined from CVS (chorionic villus sampling) or amniocentesis.
Treatment for beta thalassemia major or Cooley's anemia:
Specific treatment for beta thalassemia major or Cooley's anemia will be determined by your doctor based on:
- Your age, overall health, and medical history
- Extent of the disease
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference
Treatment may include:
- Regular blood transfusions
- Medications (to decrease amount of iron in the body, called chelation therapy)
- Splenectomy--surgical removal of the spleen (if necessary)
- Daily doses of folic acid
- Possible surgical removal of the gallbladder
- No iron supplements
- Bone marrow transplantation has been used, but is still considered experimental