What is alpha thalassemia?
Thalassemia is an inherited problem. That means it is passed down from one or both parents through their genes. It affects the production of normal hemoglobin. Hemoglobin is a protein in red blood cells that carries oxygen to the tissues of the body.
Thalassemia includes a number of different forms of anemia, including the alpha thalassemias. The severity and type of anemia depends on how many genes are affected.
What causes alpha thalassemia?
Alpha thalassemia is caused by errors in the alpha chain of the hemoglobin molecule.
Normally, there are 2 alpha genes on each #16 chromosome. There is a total of 4 genes; 2 from each parent.
How these genes are changed determines the type of alpha thalassemia in a person:
- Alpha thalassemia major. All 4 alpha chain genes are deleted. Hemoglobin Bart hydrops fetalis is another term for this condition. This causes anemia so severe that death most often occurs before birth.
- Alpha thalassemia carrier. Just 2 alpha chain genes are deleted. Alpha thalassemia minor or alpha thalassemia-1 trait are other terms for this condition.
- If both deleted genes are from the same #16 chromosome, it is called a cis deletion. It is inherited from one parent.
- If instead 1 gene is missing from both #16 chromosomes, it is called a trans deletion. It is inherited from both parents.
- When both parents are carriers of the cis deletion, there is a 1 in 4 chance with each pregnancy of having a baby with alpha thalassemia major.
- DNA testing is usually done from a blood sample. It looks at the alpha chain genes on each #16 chromosome to find out which are deleted.
- Hemoglobin H disease. In this form, 3alpha chain genes are deleted. Hemoglobin H disease occurs when a person inherits a cis deletion from one parent and a trans deletion from the other. This leaves just one working alpha chain gene. This results in a severe hemolytic anemia. Symptoms can worsen with fever or exposure to certain drugs, chemicals, or infectious agents. It often requires blood transfusions. People with hemoglobin H disease are at greater risk of having a child with alpha thalassemia major.
- Silent alpha thalassemia carrier. One alpha chain gene is deleted (the other 3 are normal). Alpha thalassemia minima or alpha thalassemia-2 trait are other terms for this condition. Blood tests are usually normal. The red cells may be small. This may suggest that the person is a silent carrier. This is confirmed by DNA tests.
Who is at risk for alpha thalassemia?Alpha thalassemia is a genetic disease inherited from one or both parents. So, the only risk factor is a family history of the disease.
What are the symptoms of alpha thalassemia?
Symptoms of alpha thalassemia will vary, based on which type is inherited. Common symptoms may include:
- Alpha thalassemia major. This type usually results in death before birth.
- Alpha thalassemia carrier. People with this type may have mild anemia. They may have no or only mild symptoms such as mild fatigue or exercise intolerance.
- Hemoglobin H disease. This type causes moderate to severe symptoms including fatigue and exercise intolerance. They may also have an enlarged liver and/or spleen, yellow tinged skin, and leg ulcers.
- Silent alpha thalassemia carrier. People with this type have no symptoms.
How is alpha thalassemia diagnosed?
Alpha thalassemia is most commonly found in:
- Middle East
- Southeast Asia
- Southern China
- Mediterranean region
Carrier status can be suggested by the following:
- Complete blood count (CBC). A measurement of size, number, and maturity of different blood cells in a set volume of blood.
- Hemoglobin electrophoresis with A2 and F quantitation. A lab test that tells what type of hemoglobin is present.
- FEP (free-erythrocyte protoporphyrin) and ferritin. This test is done to rule out iron-deficiency anemia.
All of these tests can be done on a single blood sample. Prenatal diagnosis is done with CVS (chorionic villus sampling) or amniocentesis. Confirmation of alpha thalassemia requires DNA test.
How is alpha thalassemia treated?
Your health care provider will figure out the best treatment based on:
- How old you are
- Your overall health and medical history
- How sick you are
- How well you can handle specific medications, procedures, or therapies
- How long the condition is expected to last
- Your opinion or preference
Treatment may include:
- Daily doses of folic acid
- Blood transfusions (as needed)
- Surgical removal of the spleen
- Chelation treatments to remove excess iron from the body
- Avoidance of certain oxidant drugs in hemoglobin H disease
Living with alpha thalassemia
People with alpha thalassemia may have no symptoms or many symptoms. If you do not have symptoms, you may still want to see a specialist. He or she can help you understand the risks of passing the disease to your children.
If you have symptoms, it is important to work with your health care provider to find the best treatment to minimize the symptoms of anemia.
Key points about alpha thalassemia
- Alpha thalassemia is an inherited disorder that affects the production of normal hemoglobin.
- There are 4 variations of alpha thalassemia, depending on how the disease is inherited
- People who have alpha thalassemia can pass the disease on to their children.
- Alpha thalassemia may cause no symptoms, mild symptoms, or moderate to severe symptoms.
- There is no cure for alpha thalassemia. Treatment can minimize the symptoms.
Next stepsTips to help you get the most from a visit to your health care provider:
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells you.
- At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
- If you have a follow-up appointment, write down the date, time, and purpose for that visit.
- Know how you can contact your provider if you have questions.