About alpha thalassemia
What is alpha thalassemia?
What is alpha thalassemia?
Alpha thalassemia is a blood disorder that reduces the production of normal hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen to cells throughout the body.
What are the types of alpha thalassemia?
Two types of alpha thalassemia can cause health problems. The more severe type is known as hemoglobin Bart hydrops fetalis syndrome or Hb Bart syndrome. The milder form is called HbH disease.
Hb Bart syndrome is characterized by hydrops fetalis, a condition in which excess fluid builds up in the body before birth. Additional signs and symptoms can include severe anemia, an enlarged liver and spleen (hepatosplenomegaly), heart defects, and abnormalities of the urinary system or genitalia. As a result of these serious health problems, most babies with this condition are stillborn or die soon after birth. Hb Bart syndrome can also cause serious complications for women during pregnancy, including dangerously high blood pressure with swelling (preeclampsia), premature delivery, and abnormal bleeding.
HbH disease causes mild to moderate anemia, hepatosplenomegaly, and yellowing of the eyes and skin (jaundice). Some affected individuals also have bone changes such as overgrowth of the upper jaw and an unusually prominent forehead. The features of HbH disease usually appear in early childhood, but affected individuals typically live into adulthood.
How Common Is Alpha Thalassemia?
Alpha thalassemia is a fairly common blood disorder worldwide. Thousands of infants with Hb Bart syndrome and HbH disease are born each year, particularly in Southeast Asia. Alpha thalassemia also occurs frequently in people from Mediterranean countries, North Africa, the Middle East, India, and Central Asia.
What are the symptoms for alpha thalassemia?
Thalassemia signs and symptoms can include:
- Pale or Yellowish skin
- Facial bone deformities
- Slow growth
- Abdominal Swelling
- Dark urine
Some babies show signs and symptoms of thalassemia at birth; others develop them during the first two years of life. Some people who have only one affected hemoglobin gene don't have thalassemia symptoms.
What are the causes for alpha thalassemia?
Alpha thalassemia typically results from deletions involving the HBA1 and HBA2 genes. Both of these genes provide instructions for making a protein called alpha-globin, which is a component (subunit) of hemoglobin.
People have two copies of the HBA1 gene and two copies of the HBA2 gene in each cell. Each copy is called an allele. For each gene, one allele is inherited from a person's father, and the other is inherited from a person's mother. As a result, there are four alleles that produce alpha-globin. The different types of alpha thalassemia result from the loss of some or all of these alleles.
Hb Bart syndrome, the most severe form of alpha thalassemia, results from the loss of all four alpha-globin alleles. HbH disease is caused by a loss of three of the four alpha-globin alleles. In these two conditions, a shortage of alpha-globin prevents cells from making normal hemoglobin. Instead, cells produce abnormal forms of hemoglobin called hemoglobin Bart (Hb Bart) or hemoglobin H (HbH). These abnormal hemoglobin molecules cannot effectively carry oxygen to the body's tissues. The substitution of Hb Bart or HbH for normal hemoglobin causes anemia and the other serious health problems associated with alpha thalassemia.
Two additional variants of alpha thalassemia are related to a reduced amount of alpha-globin. Because cells still produce some normal hemoglobin, these variants tend to cause few or no health problems. A loss of two of the four alpha-globin alleles results in alpha thalassemia trait. People with alpha thalassemia trait may have unusually small, pale red blood cells and mild anemia. A loss of one alpha-globin allele is found in alpha thalassemia silent carriers. These individuals typically have no thalassemia-related signs or symptoms.
What are the treatments for alpha thalassemia?
Mild forms of thalassemia trait don't need treatment.
For moderate to severe thalassemia, treatments might include:
- Frequent blood transfusions. More severe forms of thalassemia often require frequent blood transfusions, possibly every few weeks. Over time, blood transfusions cause a buildup of iron in your blood, which can damage your heart, liver and other organs.
Chelation therapy. This is treatment to remove excess iron from your blood. Iron can build up as a result of regular transfusions. Some people with thalassemia who don't have regular transfusions can also develop excess iron. Removing the excess iron is vital for your health.
To help rid your body of the extra iron, you might need to take an oral medication, such as deferasirox (Exjade, Jadenu) or deferiprone (Ferriprox). Another drug, deferoxamine (Desferal), is given by needle.
Stem cell transplant. Also called a bone marrow transplant, a stem cell transplant might be an option in some cases. For children with severe thalassemia, it can eliminate the need for lifelong blood transfusions and drugs to control iron overload.
This procedure involves receiving infusions of stem cells from a compatible donor, usually a sibling.
- Blood transfusion
- Bone marrow transplant
What are the risk factors for alpha thalassemia?
Factors that increase your risk of thalassemia include:
- Family history of thalassemia. Thalassemia is passed from parents to children through mutated hemoglobin genes.
- Certain ancestry. Thalassemia occurs most often in African Americans and in people of Mediterranean and Southeast Asian descent.