Difference Between Thalassemia Minor and Thalassemia Major
What Is Thalassemia?
There are several types of this inherited form of anemia, in which gene problems negatively affect the production of hemoglobin — and therefore the delivery of oxygen to the cells.
By Susan L Sullivan
Medically Reviewed by Lindsey Marcellin, MD, MPH
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Thalassemias are a group of inherited blood disorders caused by defective hemoglobin, which is the protein inside each red blood cell that carries oxygen throughout the body. Those with thalassemia are most likely chronically anemic.
Each type of thalassemia is a result of the body’s inability to make enough red blood cells and hemoglobin. Hemoglobin A, which is the normal type of hemoglobin, is made up of two alpha globin and two beta globin protein chains. Genes from each parent are needed to make each of these protein chains. If there is a defect in either protein chain, alpha (in which the defect is in the alpha globin protein) or beta (in which the defect is in the beta globin protein) thalassemia can occur. Both alpha and beta thalassemia are further classified into these subtypes:
- Thalassemia major
- Thalassemia minor
If you inherit the defective hemoglobin gene from both parents, the more severe form of this blood disorder, thalassemia major, occurs. Babies who have alpha thalassemia major, sometimes referred to as hydrops fetalis are usually stillborn or die shortly after birth. Beta thalassemia major is also referred to as Cooley’s anemia.
Thalassemia minor occurs when you receive the defective gene from only one parent. If you have this form of the disease, you do not have symptoms but are a carrier of the blood disorder. Other forms of thalassemia include:
- Hb S/beta thalassemia.The affected person has thalassemia minor and inherits one gene for sickle cell disease. Hb S/beta thalassemia occurs most often in people of Mediterranean or African descent.
- E-beta thalassemia.The affected person has thalassemia minor and a defective gene that produces a variant form of hemoglobin called hemoglobin E. E-beta thalassemia occurs most commonly in people of Southeast Asian ancestry.
In addition to chronic anemia, symptoms of thalassemia may include an enlarged spleen. This organ filters many of the defective red blood cells out of the circulatory system. As a result, the spleen may gradually enlarge and cause jaundice or yellowing of the skin and whites of the eyes, slow growth, and dark urine. Left untreated, thalassemia can lead to serious complications, including:
- Heart and liver disease
- Bone loss or osteoporosis
Risk Factors for Thalassemia
Thalassemia affects both men and women and can occur in any population, but people of Middle Eastern, African, Asian, Greek, or Italian descent are at greater risk. The two risk factors for this blood disorder are:
- Having parents who have the missing or altered hemoglobin-making genes
- Your ethnic heritage
In the United States, there are approximately 1,000 cases total of thalassemia major, with the majority of cases in immigrants. “It is difficult to get a completely accurate count because many patients are treated outside of the nine Thalassemia Treatment Centers established by the Centers for Disease Control,” says Jeanne Boudreaux, MD, a pediatric hematologist and oncologist at the AFLAC Cancer Center and Blood Disorders Service of Children’s Healthcare of Atlanta.
Worldwide, there are about 30,000 new cases of beta thalassemia annually, with around 300,000 people living with the blood disorder, according to Dr. Boudreaux. Millions more are affected by other forms of thalassemia (the alpha thalassemias and hemoglobin E thalassemias).
The most severe forms of these disorders occur mainly in areas of the world where malaria is endemic. The highest prevalence of carriers is in the Maldives, with an estimated 18 percent of the population carrying the trait. The areas of the world with the greatest numbers of thalassemia patients include the Mediterranean (Italy, Greece, Cyprus, and other countries in the area), Middle East (Egypt, Iran, Iraq, and other countries), Northern Africa, Near East (India, Pakistan, and other countries), and the Far East (China, Thailand, Bangladesh, and other countries).
Treatment Options for Thalassemia
“Thalassemia can be cured through stem cell transplantation,” says Harvey Luksenburg, MD, chief of the Blood Diseases Branch in the National Heart, Lung, and Blood Institute in Bethesda, Md. “Stem cell transplantation is most successful when carried out in childhood, and is only available at specialized medical centers.” Stem cells are found in bone marrow and are responsible for making red blood cells. Unfortunately, it can be difficult to find a compatible donor for a transplant, and the procedure can be risky.
Blood transfusions are the cornerstone of treatment for the severe forms of thalassemia. Patients who receive frequent transfusions will require treatment with iron chelators — substances that remove excess iron — in order to prevent heart or liver disease due to iron overload from all of the transfused red blood cells. Folic acid supplements are also needed.
Most of the medications used to treat thalassemia are aimed at trying to get rid of the excess iron that accumulates with the years of chronic transfusions. In a recent study, researchers in Greece found that intensive treatment with two chelator medications together was able to normalize the iron load in thalassemia patients and prevent or reverse complications due to iron overload from transfusions, including cardiac and endocrine problems. One of the chelator medications used in the study, deferiprone, is not yet approved by the FDA.
Two of these chelator medications are approved for use in the United States, but many more are being researched and tested. In addition, some patients will have to take other medications to treat the endocrine abnormalities that sometimes occur (for example, insulin for diabetes or calcium supplements for low bone mass).
Outlook for Thalassemia Patients
"There are several important areas of research for thalassemia,” says Boudreaux. Ongoing research includes finding better, safer drugs to treat the iron overload that occurs in all of these patients, as well investigating the use of gene therapy. Researchers are also looking at treatments using unrelated donors for bone marrow transplant.
Thalassemia patients and carriers may want to undergo genetic counseling if they are planning to have children. Prenatal screening is also available. Those with thalassemia are urged to get any recommended vaccinations and avoid others who have contagious illnesses. Most importantly, thalassemia patients need to follow a healthy lifestyle to ensure a long life.
Video: Difference Between Sickle Cell Anemia and Thalassemia
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