Pediatric 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 child:
- 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 1 to 2 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 buildup of iron in the heart and other organs, resulting in heart failure for some patients in their teens or early twenties.
- Thalassemia minor or thalassemia trait. One beta gene has a deletion, resulting in anemia. Thalassemia minor is further divided into thalassemia minima (a person has little to no symptoms) and thalassemia intermedia (a 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. The following tests help diagnose thalassemia:
- Complete blood count (CBC). A measurement of size, number, and maturity of different blood cells in a specific volume of blood.
- Hemoglobin electrophoresis. A lab procedure that differentiates the types of hemoglobin present. Only hemoglobin F and A2 are seen in beta thalassemia major.
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 child's doctor based on the following:
Your child's age, overall health, and medical history
Extent of the disease
Your child's tolerance for specific medications, procedures, or therapies
Expectations for the course of the disease
Your opinion or preference
Treatment for beta thalassemia may include:
Regular blood transfusions
Medications (to decrease amount of iron in the body, called chelation therapy)
Surgical removal of the spleen (if necessary)
Daily doses of folic acid supplements
Monitoring of the gallbladder, liver, and bone density
No iron supplements
Bone marrow transplantation from a matched donor is the only cure currently available for beta thalassemia. Other therapies are being studied, including gene therapy.
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