What is thalassemia?
Thalassemia is an inherited blood disorder that causes the body to produce less hemoglobin, the protein in red blood cells that helps them carry oxygen from the lungs to all parts of the body. Hemoglobin is made up of four parts: two alpha proteins and two beta proteins. Thalassemia affects one or more of the genes that produce these proteins.
How serious is thalassemia in children?
The severity of the disease depends on the type of thalassemia (see below). Children with thalassemia major require ongoing treatment and blood transfusions throughout their lives. In addition, they need ongoing chelation therapy to remove the excess iron that builds up in the blood from these transfusions. Milder forms of thalassemia, including thalassemia intermedia and thalassemia minor, require less aggressive or no treatment at all.
What are the different types of thalassemia?
Everyone has four alpha genes and two beta genes that together control the production of hemoglobin. There are three major types of thalassemia, classified based on the severity of symptoms and the genetic defect causing the disease:
Thalassemia minor and silent carriers
Children with thalassemia minor or trait have two alpha genes or one beta gene missing or damaged, while those that are “silent carriers” have one missing or damaged alpha gene. These children do not experience symptoms (except mild anemia in some cases of thalassemia minor), and they do not require treatment.
In children with beta thalassemia intermedia, one or both beta genes are not working properly. They have mild to severe anemia and can be diagnosed early in childhood or later in life. They may need blood transfusions during pregnancy or when very sick.
Children with thalassemia major need ongoing medical care, including blood transfusions to alleviate severe anemia and chelation therapy to remove excess iron from the blood.
There are two subtypes of thalassemia major:
Alpha thalassemia major
- most serious and most rare form of the subtypes of thalassemia
- all four alpha genes are missing
- if untreated, leads to miscarriage or death of the baby shortly after birth
- may be treated with blood transfusions in the womb if discovered early enough in the pregnancy
- babies who survive require lifelong blood transfusions or stem cell transplant and extensive medical care
Beta thalassemia major (also called Cooley’s anemia, after the discoverer)
- neither beta gene is not working properly
- symptoms, which begin during the first year of life, include severe anemia
- monthly blood transfusions needed
- chelation therapy also is needed to remove excess iron that builds up in the body due to frequent blood transfusions
Other types of thalassemia
- Hemoglobin E beta-thalassemia: This form of thalassemia is more common in children of Southeast Asian descent. It results from two separate genetic defects:
- a defective type of hemoglobin known as hemoglobin E
- a defective gene that causes beta thalassemia
- Hemoglobin H disease alpha-thalassemia: This form of thalassemia is most common in Southern China and Southeast Asia. In Hemoglobin H disease:
- three alpha genes are missing
- moderate to severe anemia may occur
- frequent blood transfusions may be needed
- genetic counseling and screening may be needed in adulthood, as the risk of having children with alpha thalassemia major is increased
Is thalassemia common?
The defective genes that cause thalassemia are relatively common, especially in people of South Asian, African and Mediterranean descent. However, thalassemia occurs in many populations around the world.
About 300 million people around the world have the “thalassemia trait,” which puts them at risk of having children with some form of thalassemia. More than 1 million people have thalassemia intermedia, while more than 100,000 people have thalassemia major. In the United States, there are only about 1,000 people with thalassemia major.
Hemoglobin H disease and Hemoglobin E/beta thalassemia are extremely common in Southern China and South and Southeast Asia.
What are the symptoms of thalassemia?
Symptoms of thalassemia depend on the number of genes affected and can range from no symptoms at all to severe anemia.
The primary symptoms of thalassemia are a result of anemia, a decreased number of healthy red blood cells. However, each child may experience symptoms differently.
The following are the most common symptoms of anemia:
- pale skin, lips, hands or under the eyelids
- increased heart rate (tachycardia)
- breathlessness, or difficulty catching a breath (dyspnea)
- lack of energy, or tiring easily (fatigue)
- dizziness or vertigo, especially upon standing
- irregular menstruation cycles
- absent or delayed menstruation (amenorrhea)
- jaundice, or yellowing of skin, eyes and mouth
- enlarged spleen or liver (splenomegaly, hepatomegaly)
- slow or delayed growth and development
Thalassemia intermedia causes less severe symptoms than thalassemia major, which can make it difficult to diagnose, because it may resemble other forms of anemia.
Thalassemia major causes the most severe anemia and requires ongoing treatment and regular blood transfusions.