What is thalassemia?
Thalassemia is a group of blood diseases caused by production of abnormal hemoglobin. Hemoglobin is a protein found in red blood cells that carries oxygen to the body. Having lower levels of hemoglobin is called anemia. Thalassemia is an inherited form of anemia, meaning it is passed down through families. It cannot be passed to another person through person-to-person contact. It most commonly affects children of Chinese, South Asian, Middle Eastern, Mediterranean or African descent.
Types of thalassemia
There are many different types of thalassemia, and the degree of symptoms can vary. The two main types are alpha and beta. Beta thalassemia is the most common.
Beta thalassemia
Typically, each person receives two beta-globin genes, one from each parent. If one of these genes has a variant (is changed), this is called beta thalassemia trait or thalassemia minor. Your child may have mild symptoms or no symptoms and is not likely to need treatment for this type of thalassemia.
When there are two changed genes, this is called thalassemia intermedia or thalassemia major, depending on how the genes are impacted.
Thalassemia intermedia
In thalassemia intermedia, one of the genes is severely impacted, and the other is mildly impacted. Symptoms develop later in life, at approximately 2 years of age. Your child may have moderate symptoms of anemia. Many children with this type of thalassemia do not need blood transfusions or only need them once in a while.
Thalassemia major
In thalassemia major, both genes are severely impacted. Children with thalassemia major have symptoms within the first year of life, such as fatigue or slow growth. Their body experiences significant anemia, and their bone marrow may expand to help produce more red blood cells. This can lead to changes in the face and bones, cause bones to be fragile, affect activity levels and lead to enlarged liver and spleen. Children with thalassemia major typically receive regular blood transfusions and iron chelation therapy. These treatments are explained further in the sections below.
Alpha thalassemia
Typically, each person receives four alpha-globin genes, two from each parent.
- If your child has one changed or missing gene, their red blood cells may be smaller than normal, but they should not have any symptoms. No treatment is typically needed. This is considered as being a silent carrier for alpha thalassemia, meaning your child does not have the disease but can pass on the gene change to their children.
- If your child has two mutated or missing genes, they can experience symptoms of mild anemia. No treatment is typically needed. This is called alpha thalassemia minor or alpha thalassemia trait.
- If your child has three mutated or missing genes, this is called hemoglobin H disease. Symptoms can range from mild to moderately severe anemia, depending on the impacted genes. Some children may need blood transfusions.
- If all four genes are missing, this is called alpha thalassemia major or hemoglobin Barts. This is typically diagnosed during pregnancy with ultrasounds and DNA testing. A fetus with alpha thalassemia major will have severe anemia while in utero and require blood transfusions throughout the pregnancy. These are called intrauterine blood transfusions. After delivery, these children receive monthly blood transfusions to manage the condition.
Signs and symptoms of thalassemia
Children with thalassemia major may show signs and symptoms in early infancy. The symptoms are similar to children with anemia:
- pale skin
- feeling cold
- fatigue or tiring easily
- weakness or dizziness
- shortness of breath
Other symptoms may include:
- irritability
- yellow discolouration of skin (jaundice) or eyes (scleral icterus)
- slow growth and poor appetite
- protruding abdomen with an enlarged spleen
- irregular facial bone structure
- tea-coloured or dark urine
- delayed puberty
How is thalassemia diagnosed?
Your child's health-care provider will take into consideration the signs and symptoms you have observed. A diagnosis can only be confirmed by blood tests:
- a complete blood count (CBC) to measure hemoglobin and the size of the red blood cells
- a reticulocyte count to measure how many red blood cells the bone marrow produces
- iron studies to check for iron deficiency anemia
- hemoglobin electrophoresis to see different types of hemoglobin
- genetic testing to check for changes in genes
Treatment
If your child is experiencing mild symptoms of anemia, treatment is not typically needed.
If your child is experiencing moderate to severe symptoms of anemia, blood transfusions can provide the red blood cells they need to thrive. However, recurrent blood transfusions can cause an overload of iron in your child's body. This can damage the heart, liver and endocrine system (the glands that produce and regulate hormones). If your child has too much iron in their body, they will receive medicine (called iron chelators) to remove the excess iron and prevent damage.
The only way to cure thalassemia is with a bone marrow transplant. New therapies are also currently being explored, such as gene therapy.
Prevention
Thalassemia cannot be prevented, but genetic testing can determine if you carry an impacted gene. This can be helpful in future family planning. Genetic counselling may also be helpful if you or your partner carries a gene mutation for thalassemia. Prenatal testing is also available.
Complications
A child with this blood disorder may have gallstones. Some children may have poor growth.
Heart failure and infection are the leading causes of death among children when the disorder is left untreated. With treatment, the major complications are related to iron overload.
When to seek medical assistance
If your child shows signs and symptoms of anemia, visit your child's health-care provider as soon as possible. If you have a family history of thalassemia, you should be tested to see if you are a carrier.
At SickKids
For information about the Division of Haematology/Oncology at SickKids, visit www.sickkids.ca/en/care-services/clinical-departments/haematology-oncology-cancer.