Alpha Thalassemia Types, Diagnosis, and Treatment

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Alpha thalassemia is inherited anemia where the body is unable to produce a normal amount of hemoglobin. Hemoglobin is the protein in red blood cells that carries oxygen throughout your body.

Hemoglobin A (the major hemoglobin in adults) contains alpha-globin chains and beta-globin chains. In alpha thalassemia, there is a reduced amount of alpha-globin chains.

Close up of scientist's hands selecting a blood sample for medical testing
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Types

Two types of alpha thalassemia can lead to health problems—Hb Bart syndrome and HbH disease.

Hb Bart Syndrome

This syndrome is the most severe form of alpha thalassemia. It is also known as hemoglobin Bart hydrops fetalis syndrome and alpha thalassemia major. In this syndrome, excess fluid builds up in a fetus' body before birth. It can cause:

  • Severe anemia
  • Hepatosplenomegaly (enlarged liver and spleen)
  • Heart defects
  • Congenital abnormalities in the urinary tract and genitals

Most babies born with Hb Bart syndrome are stillborn or die shortly after birth. In addition, the condition can cause pregnancy complications, including preeclampsia, premature birth, and bleeding.

HbH Disease

Hemoglobin H (HbH) is the milder form of alpha thalassemia. The symptoms usually appear in early childhood. The condition may cause:

  • Mild to moderate anemia
  • Hepatosplenomegaly
  • Jaundice

People with HbH disease usually live into adulthood.

Symptoms

Alpha thalassemia symptoms vary depending on the severity of the disease. Symptoms may include:

  • Anemia
  • Enlarged forehead
  • Enlarged liver and spleen
  • Fatigue
  • Gallstones
  • Jaundice
  • Leg ulcers
  • Preeclampsia (during pregnancy)

Who's at Risk

Alpha thalassemia is an inherited condition that requires both parents to be carriers. Therefore, the risk of having a child with alpha thalassemia disease depends on the status of the parents. 

People have four alpha-globin proteins that form the HBA1 and the HBA2 genes (called alleles). When some or all of these alleles are missing, alpha thalassemia occurs. The risk is as follows:

  • 1 mutated allele: A person is a carrier with no symptoms of the disease. This is also known as alpha thalassemia silent.
  • 2 mutated alleles: A person may have mild alpha thalassemia symptoms (known as alpha thalassemia minor or alpha thalassemia trait).
  • 3 mutated alleles: A person has moderate to severe symptoms (HbH disease).
  • 4 mutated alleles: A fetus will have Hb Bart syndrome (alpha thalassemia major or hydrops fetalis). This condition is usually fatal before or shortly after birth.

Thousands of babies are born with alpha thalassemia every year. It is most prevalent in Asia, Africa, and the Mediterranean area. 

In the US, approximately 30% of African-Americans have alpha thalassemia.

Diagnosis

Diagnosing alpha thalassemia depends on the severity of the disease.

Silent Carrier

Alpha thalassemia silent causes no laboratory changes on a complete blood count (CBC), which is why it is called silent carrier. Alpha thalassemia is usually suspected after a person's child is born with HbH disease. Doctors can diagnose silent carriers with genetic testing.

Alpha Thalassemia Minor

Occasionally alpha thalassemia minor is identified on a newborn screen, but not in all cases. A problem usually comes to light during a routine CBC.

The CBC will reveal a mild to moderate anemia with very small red blood cells. Small red blood cells can be confused with iron deficiency anemia.

In general, if a doctor rules out iron deficiency anemia and beta thalassemia trait, the person has alpha thalassemia trait. If necessary, a doctor can confirm this with genetic testing.

HbH Disease

Doctors can identify hemoglobin H on the newborn screen as well. A hematologist will monitor children with this diagnosis, closely. In addition, some patients are identified later in life during a work-up for anemia.

Hb Bart Syndrome

Hydrops fetalis is not a specific diagnosis but rather characteristic features on a neonatal ultrasound. If a fetus has fluid accumulation (known as hydrops), a doctor will do a work-up to find the cause. In Hb Bart syndrome, four alpha-globin genes are missing.

Treatments

No treatment is needed for people who are silent carriers (minima) or for alpha thalassemia minor. Although, people with alpha thalassemia minor will have lifelong mild anemia. Those with more moderate to severe cases may require blood transfusions or chelation therapy.

Transfusions

People with HbH disease usually have moderate anemia that is well-tolerated. However, transfusions are occasionally needed during illnesses with a fever due to accelerated red blood cell breakdown.

Adults may require more regular transfusions. Those with a more severe form of HbH disease (called Hemoglobin H-Constant Spring disease) can have significant anemia and require frequent transfusions during their lifetime.

Iron Chelation Therapy

People with HbH disease may develop iron overload. This may occur even in the absence of blood transfusions secondary to increased absorption of iron in the small intestine. Medications called chelators can help rid the body of excess iron.

Summary

Alpha thalassemia is an inherited disorder in which the body can not produce enough hemoglobin. The condition ranges from asymptomatic to severe.

Sometimes, a person can be a carrier (silent alpha thalassemia) with no sign of disease. Others may have very mild disease, known as having alpha thalassemia trait.

The two types of alpha thalassemia that cause health problems are Hb Bart syndrome and HbH disease. Hb Bart syndrome is diagnosed prenatally and is fatal before birth or shortly after. HbH disease is often diagnosed in childhood. However, people with HbH live well into adulthood.

A Word From Verywell

Remember that both parents must be carriers for a child to be born with alpha thalassemia. Doctors can diagnose alpha thalassemia with blood tests; however, a blood test won't detect it if someone is a silent carrier.

Genetic testing can confirm if you are a silent carrier. Talk to your doctor if you are concerned about alpha thalassemia. They may recommend genetic testing and blood work.

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