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Beta Thalassemia Trait

What is beta thalassemia trait?

Beta thalassemia trait is a change (mutation) in a gene that helps make hemoglobin in red blood cells. People with the trait have a missing or damaged gene. Beta thalassemia trait is also called beta thalassemia minor.

A trait is different from a disease

Most people with beta thalassemia trait have no signs or symptoms of illness. The trait can sometimes cause mild anemia. But it normally does not cause serious problems.

People with beta thalassemia trait do not have beta thalassemia disease or sickle cell disease. They cannot develop the conditions later in life. But they can pass the genes for beta thalassemia or sickle beta thalassemia on to their children.

  • Beta thalassemia is an inherited blood disorder that causes you to make fewer red blood cells and less hemoglobin. Hemoglobin is a protein that carries oxygen from the lungs to all parts of your body. There are two parts of hemoglobin: alpha globin and beta globin. The specific hemoglobin protein affected in beta thalassemia is the beta globin.
  • Sickle beta thalassemia is a type of sickle cell disease. Depending on the amount of hemoglobin produced, a person may have sickle beta plus thalassemia or sickle beta zero thalassemia. A person with sickle cell disease has red blood cells that can sickle or become banana shaped. Sickle cell disease is a lifelong condition that can cause serious health problems. People with sickle cell disease need ongoing medical treatment. Learn more about sickle cell disease.

Risk factors for beta thalassemia trait

Beta thalassemia trait is common in people whose ancestors came from Africa, Asia, the Middle East, or the Mediterranean region. But it is possible for a person of any nationality or ancestry to have beta thalassemia trait.

Tests for beta thalassemia trait

A blood test can let you know if you have beta thalassemia trait. It may be done as part of newborn testing or genetic screening. Your doctor may also recommend testing if someone in your family has beta thalassemia.

How beta thalassemia trait is inherited

Beta thalassemia runs in families. Like eye color or hair color, the genes for thalassemia trait are inherited, or passed from parents to children. Whether a child has the blood disorder depends on if they inherit the trait from one or both parents.

If one parent has beta thalassemia trait and the other parent has normal hemoglobin:

With each pregnancy, there is a 50% (1 in 2) chance of having a child with beta thalassemia trait. This chance is the same for boys and girls.

These are the possible outcomes with each pregnancy:

  • 50% (1 in 2) chance of having a child with beta thalassemia trait
  • 50% (1 in 2) chance of having a child without trait
Graphic showing parent traits with one parent carrying the beta thalassemia trait and the second parent having no traits. This results in a 1 in 2 chance of having a child with the beta thalassemia trait or a 1 in 2 chance of having a child without it.
 

If one parent has beta thalassemia trait and the other parent has sickle cell trait:

With each pregnancy, there is a 25% (1 in 4) chance of having a child with sickle cell disease (sickle beta thalassemia).

These are the possible outcomes with each pregnancy:

  • 25% (1 in 4) chance of having a child with beta thalassemia trait
  • 25% (1 in 4) chance of having a child with sickle cell trait
  • 25% (1 in 4) chance of having a child with sickle beta thalassemia disease
  • 25% (1 in 4) chance of having a child without trait or disease
Graphic showing parent traits with one parent carrying the beta thalassemia trait and the other parents carrying a sickle cell trait results in a 25% chance of having a child with sickle cell disease, a 25% chance of having a child with the beta thalassemia trait, a 25% chance of having a child with sickle cell trait, and a 25% chance of having a child without the trait or disease
 

If both parents have beta thalassemia trait:

With each pregnancy, if both parents have beta thalassemia trait, there is a 25% (1 in 4) chance of having a child with beta thalassemia disease.

These are the possible outcomes with each pregnancy:

  • 25% (1 in 4) chance of having a child with beta thalassemia disease
  • 50% (1 in 2) chance of having a child with beta thalassemia trait
  • 25% (1 in 4) chance of having a child without trait or disease
Graphic showing parent traits with both paents carrying the beta thalassemia trait results in a 25% chance of having a child with beta thalassemia disease, a 50% chance of having a child with the beta thalassemia trait, and a 25% chance of having a child without the trait or disease
 

The severity of symptoms depends on the type of beta thalassemia a person has.

  • Beta thalassemia trait (beta thalassemia minor) causes no symptoms or mild anemia symptoms.
  • Beta thalassemia intermedia causes mild to moderate anemia.
  • Beta thalassemia major (Cooley’s anemia) causes more severe anemia. This condition is known as “transfusion-dependent thalassemia” because it requires lifelong blood transfusions.

Beta thalassemia disease is a lifelong blood disorder that can cause serious health problems. People with this disease need medical treatment.

To learn more about trait conditions, talk to your doctor or genetic counselor. Your care team can give you more details about your trait status and that of your child.

Key points about beta thalassemia trait

  • Beta thalassemia trait is inherited from one’s parents, like hair or eye color. 
  • Beta thalassemia is most common in people of African, Mediterranean, Asian, and Middle Eastern descent.
  • People with beta thalassemia trait have both normal hemoglobin and abnormal beta thalassemia hemoglobin in their red blood cells.
  • Normally, beta thalassemia trait does not cause any health problems.
  • Beta thalassemia trait is also known as beta thalassemia minor. 
  • Parents who have beta thalassemia trait can have a child with beta thalassemia disease or sickle cell disease. 

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Reviewed: November 2023