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 depends upon 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. Thal 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 and brittle. 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 twenties.
- thalassemia minor or thalassemia trait - one beta gene has a deletion, resulting in anemia. Thal minor is further divided into:
- Thalassemia minima - person has little to no symptoms
- Thalassemia intermedia - person has moderate to severe anemia
Persons with thal minor have a 50/50 chance to pass the gene to their offspring, who would also have thal 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 consult a hematologist regarding any treatment.
Thal 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 thal minor.
How is beta thalassemia diagnosed?
The frequency of this gene in the general population is about one in 300, while persons who are of Mediterranean ancestry (Greek or Italian) have a risk of about one in 30 for carrying this gene. Each child of two carrier parents is at 25 percent risk for the disease. Carrier status can be determined by:
- Complete blood count (CBC) - a measurement of size, number and maturity of different blood cells in a specific volume of blood.
- Hemoglobin electrophoresis with 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 child's physician 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.
- Possible surgical removal of the gallbladder.
- No iron supplements.
- Bone marrow transplantation.