What is Beta Thalassemia?

Red blood cells in vein
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Beta thalassemiais an inherited blood disorder characterized by a shortage of hemoglobin, the iron-containing protein that helps red blood cells carry oxygen to organs throughout the body. The result is often mild to severe anemia and other complications over time, such as iron overload. Beta thalassemia is generally classified into three types, depending on the severity of symptoms: beta thalassemia major (also known as Cooley's anemia), which is the most severe form of the blood disorder, beta thalassemia minor, and beta thalassemia intermedia.. Blood transfusions and iron chelation are the primary treatments for beta thalassemia.

Causes

Beta thalassemia is caused by changes (mutations) in the hemoglobin beta (HBB) gene in blood cells. Individuals with beta thalassemia minor have a mutation in one HBB gene, while individuals with thalassemia major and intermedia have mutations in both HBB genes.

Types of Thalassemia

There are three types of thalassemia. They differ in the number of mutated genes they involve and the resulting severity of symptoms:

  • Beta thalassemia major (Cooley’s anemia) occurs when both beta-globin genes are severely mutated. Symptoms may be moderate to severe.
  • Beta thalassemia minor (beta thalassemia trait) occurs when one beta-globin gene is mutated. Symptoms are often mild.
  • Beta thalassemia intermedia occurs when both beta-globin genes are mutated, but the mutations are less severe than those that typically cause beta thalassemia major. Symptoms may not be present at birth, but generally develop by 2 years of age.

Thalassemia Symptoms

The symptoms of beta thalassemia depend on the type and severity of the disorder. Children born with the beta thalassemia major or intermedia may not show symptoms at birth, but usually exhibit them within the first two years of life—often between 3 and 6 months of age. Common symptoms of beta thalassemia major are:

  • Anemia
  • Fatigue
  • Weakness
  • Shortness of breath
  • Yellowish or pale skin
  • Slow growth
  • Dark urine
  • Poor appetite
  • Fussiness

Beta thalassemia is more prevalent among people of Mediterranean, Asian, Indian, and African descent.

Over time, people with beta thalassemia major may also exhibit other serious symptoms including:

  • Abdominal swelling
  • Bone deformities and broken bones from changes in the bone marrow (where red blood cells are produced)
  • An enlarged spleen because the organ works harder than normal
  • Infections

Individuals with beta thalassemia minor usually don't develop symptoms of the disorder but may have a mild anemia. Many individuals with beta thalassemia minor go through life never knowing they carry an altered gene for the blood disorder.

Diagnosis

Beta thalassemia can be diagnosed through various blood tests. Moderate and severe beta thalassemia are usually diagnosed in early childhood or by the time your are 2 years old because signs and symptoms such as anemia usually present very early. If your parents have the disorder, you may have been tested and diagnosed at birth or as a toddler, especially if you exhibited anemia at a very young age.

The various tests used to diagnose beta thalassemia include:

  • The newborn screen, which is testing administered routinely to most infants at birth to identify any inherited conditions. This can detect beta thalassemia or, at least, red-flag characteristics of the disorder in the blood for further monitoring by a hematologist. The newborn screen involves taking a small sample of blood and sending it to a lab for evaluation.
  • A complete blood count (CBC), which measures hemoglobin and the quantity and size of red blood cells. The CBC will also reveal a mild to moderate anemia with very small red blood cells, which are typical of beta thalassemia. (Sometimes, however, a diagnosis can be confused with iron deficiency anemia)

People who have milder forms of thalassemia might be diagnosed after a routine blood test shows they have anemia. Doctors may also suspect and test for beta thalassemia in people of African, Mediterranean, or Eastern Asian descent who seem to have anemia.

  • A reticulocyte count, which determines the health of bone marrow and is often part of a workup when testing for anemia, may indicate that bone marrow is not producing an adequate number of red blood cells.
  • Check of iron levels in the blood will show whether the cause of the anemia is iron deficiency or thalassemia.

Since beta thalassemia is a genetic disorder passed from parent to child, several other tests that can help predict the presence of the gene, and possible severity of beta thalassemia:

  • Hemoglobin electrophoresis, which is a blood test for parents designed to detect various genetic abnormalities in hemoglobin structure, can show the levels of hemoglobin.
  • Pre-natal testing can reveal the severity of beta thalassemia in cases where parents carry the gene. These may include: chorionic villus sampling done around the 11th week of pregnancy removing a tiny piece of the placenta for evaluation; and amniocentesis, which is done around the 16th week of pregnancy and involves examining a sample of the fluid that surrounds the fetus.

Treatment

The standard treatments for people with moderate or severe beta thalassemia are blood transfusions, iron chelation therapy, and folic acid supplements:

  • Blood transfusions: A transfusion of red blood cells can compensate for the shortage and ensures normal hemoglobin levels. People with beta thalassemia major often need transfusions every two or four weeks throughout their lives; those with beta thalassemia intermedia may require only occasional transfusions, during periods of illness or puberty.
  • Iron chelation therapy: This helps the body remove excess, and potentially harmful, amounts of iron from the blood—which can result from many transfusions. Iron chelation is administered orally or through an infusion under the skin.
  • Splenectomy: Use of this procedure has declined in recent years, but removal of the spleen is sometimes considered when chelation therapy isn't working.
  • Folic acid supplements: Folic acid is a B vitamin that helps build healthy red blood cells. Your doctor may recommend folic acid supplements in addition to blood transfusions and iron chelation therapy.
  • Bone marrow and stem cell transplant: A blood and marrow stem cell transplant replaces faulty stem cells with healthy ones from another person (a donor). Stem cells are the cells inside bone marrow that make red blood cells. Although this could be a possible cure for beta thalassemia, only a small number of people who have severe thalassemia can find a good donor match for this risky procedure.

People who are beta thalassemia carriers or who have been identified with the trait but have mild symptoms or none at all, usually require very little by way of treatment.

A Word From Verywell

If you or members of your family have beta thalassemia or the gene for beta thalassemia, it is a good idea to talk to your doctor if you are thinking about having children. A genetic counselor can help determine the risk of passing the disorder on to your offspring. If you're expecting a baby and you and your partner are thalassemia carriers, you may want to consider prenatal testing. While these tests admittedly seem scary and foreboding, they will actually assuage your anxiety and help you be prepared, whatever the outcome.

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Article Sources
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