|SSM Cardinal Glennon Children's Medical Center|
Thalassemias are a group of blood disorders that affect the way the body makes hemoglobin. Hemoglobin is a protein found in red blood cells that carries oxygen throughout the body. It's made up of alpha globin and beta globin.
The body contains more red blood cells than any other type of cell, and each has a life span of about 4 months. Each day, the body produces new red blood cells to replace those that die or are lost from the body.
With thalassemia, the red blood cells are destroyed at a faster rate, leading to anemia, a condition that can cause fatigue and other complications.
Thalassemias are inherited conditions — they're carried in the genes and passed on from parents to children. People who are carriers of a thalassemia gene show no thalassemia symptoms and might not know they're carriers. If both parents are carriers, they can pass the disease to their kids. Thalassemias are not contagious.
While there are many different types of thalassemias, the main two are:
When the gene that controls the production of either of these proteins is missing or mutated, it results in that type of thalassemia.
About Alpha Thalassemia
Normally, each person has four genes for alpha globin. Alpha thalassemia happens when one or more of the genes that control the making of alpha globins is absent or defective. It can cause anemia ranging from mild to severe and is most commonly found in people of African, Middle Eastern, Chinese, Southeast Asian, and, occasionally, Mediterranean descent.
Some children with alpha thalassemia have no symptoms and require no treatment. Others with more severe cases need regular blood transfusions to treat anemia and other symptoms.
A child can only get alpha thalassemia by inheriting it from his or her parents. Genes are "building blocks" that play an important role in determining physical traits and many other things about us.
Humans are made up of trillions of cells that form the structure of our bodies and carry out specialized jobs like taking nutrients from food and turning them into energy. Red blood cells, which contain hemoglobin, deliver oxygen to all parts of the body.
All cells have a nucleus at their center, which is kind of like the brain or "command post" of the cell. The nucleus directs the cell, telling it to grow, mature, divide, or die. The nucleus contains DNA (deoxyribonucleic acid), a long, spiral-shaped molecule that stores the genes that determine hair color, eye color, whether or not a person is right- or left-handed, and many more traits. DNA, along with genes and the information they contain, is passed down from parents to their children during reproduction.
Each cell has many DNA molecules, but because cells are very small and DNA molecules are long, the DNA is packaged very tightly in each cell. These packages of DNA are called chromosomes, and each cell has 46 of them. Each package is arranged into 23 pairs — with one of each pair coming from the mother and one from the father. When a child has alpha thalassemia, there is a change in chromosome 16.
Alpha globin is made on chromosome 16. So, if any gene that tells chromosome 16 to produce alpha globin is missing or mutated, less alpha globin is made. This affects hemoglobin and decreases the ability of red blood cells to transport oxygen around the body.
Types of Alpha Thalassemia
Alpha globin is made by four genes and one or more can be mutated or missing, so there are four kinds of alpha thalassemia:
In addition to anemia and hydrops fetalis, severe cases of alpha thalassemia and hemoglobin H disease can lead to serious complications, especially if untreated. Complications of alpha thalassemia include:
The signs and symptoms of alpha thalassemia vary depending on the type that a child has and how severe it is. Children with alpha thalassemia trait and those who are silent carriers have no symptoms at all.
Some of the more common symptoms of alpha thalassemia include:
In most cases, alpha thalassemia is diagnosed before a child's second birthday or through newborn screening, a blood test given when the child is first born. Children with alpha thalassemia major may have a swollen abdomen or symptoms of anemia or failure to thrive.
If the doctor suspects alpha thalassemia, he or she will take a blood sample for testing. Blood tests can reveal red blood cells that are pale, varied in shape and size, or smaller than normal. They also can detect low red blood cell counts and cells with an uneven distribution of hemoglobin, which causes them to look like a bull's-eye when seen through a microscope.
Blood tests also can measure the amount of iron in the blood, evaluate hemoglobin, and test a child's DNA for abnormal hemoglobin genes.
If both parents are carriers of the alpha thalassemia disorder, doctors can conduct tests on a fetus before birth. This is done through either:
The amount of treatment that alpha thalassemia requires depends on how severe the symptoms are. For those with alpha thalassemia trait or silent carriers with only mild anemia from time to time, no medical treatment is necessary.
However, the blood counts in alpha thalassemia trait look a lot like the blood counts in iron deficiency anemia, which is a very common disorder. It's important for doctors to know when children have alpha thalassemia trait so that they do not treat them with iron if it's not needed.
Doctors also might recommend a folic acid supplement for kids with hemoglobin H disease to help the body make new red blood cells. In addition, these kids may require an occasional blood transfusion, particularly after surgery.
Less commonly, children with severe cases of hemoglobin H disease may require regular blood transfusions their entire lives to keep them healthy. During blood transfusions, they're given blood from donors with matching blood types. Over time, this can cause a build-up of iron in the body, so kids who receive frequent blood transfusions may have to take medications to remove excess iron from their bodies.
Currently, the only cure for thalassemia is a procedure called a bone marrow transplant (also called a stem cell transplant). Bone marrow, which is found inside bones, produces blood cells. In a bone marrow transplant, a person is first given high doses of radiation or drugs to destroy the defective bone marrow. The bone marrow is then replaced with cells from a compatible donor, usually a healthy sibling or other relative. Bone marrow transplants carry many risks, so they usually are done only in the most severe cases of thalassemia.
Because living with alpha thalassemia can be challenging, people who are carriers of alpha thalassemia trait may want to seek genetic counseling if they're considering having children.
If your child has alpha thalassemia, support groups are available to help your family cope with the obstacles presented by the disease.
Reviewed by: Robin Miller, MD