What is Thalassemia?

What is Thalassemia?

Thalassemia is an inherited blood disorder in which the bone marrow is not able to make adequate normal hemoglobin, a protein inside red blood cells that carries oxygen. This leads to a condition called anemia. Children and adults with thalassemia may have mild to severe anemia. Several types of thalassemia and a wide spectrum of severity may cause different types of complications.

  • Those with severe anemia often require regular blood transfusions and are said to have “thalassemia major.”
  • Some people with moderate anemia and intermediate symptoms may not require regular transfusions and are said to have “thalassemia intermedia.”
  • “Carriers” have mild anemia and are said to have “thalassemia minor” or “thalassemia trait.”

Types of Thalassemia


There are two main types of thalassemia: alpha and beta. Normal hemoglobin or hemoglobin A (HbA) is made of four protein chains: two “alpha-globin” chains and two “beta-globin” chains. Thalassemia occurs when there is a defect in the genes that control the production of one of these chains. You inherit four alpha globin genes: two from each parent and two beta globin genes – one from each parent – that make these protein chains.

The degree of imbalance between alpha and beta globin production determines the disease severity.

  • Alpha thalassemia. In alpha thalassemia, a defect in the gene(s) related to the alpha-globin protein exists. It occurs most often in people from Southeast Asia, the Middle East, China, and sub-Saharan Africa. Alpha thalassemia major happens when all four genes are defective, while individuals with three, two, or one defective alpha gene may have mild to no symptoms.
  • Beta-thalassemia. This is caused by defects in the gene(s) that control beta-globin production. Children with beta-thalassemia major inherit a defective gene from both parents who are carriers, while those with thalassemia minor have one faulty gene from one parent and a normal one from the other. Beta thalassemia major is also called Cooley anemia. It occurs in people from countries around the Mediterranean and has a high prevalence in Asians as well.

Signs & Symptoms of Thalassemia


Thalassemia symptoms are due to anemia. The severity depends on the type of thalassemia you have. If you have alpha or beta thalassemia trait, you’ll likely have mild symptoms of anemia, like becoming easily tired.

Beta thalassemia intermedia may cause symptoms of moderate to severe anemia, as well as the following thalassemia symptoms:

  • Fatigue
  • Shortness of breath
  • Paleness
  • Dizziness and fainting
  • Headaches
  • Enlarged spleen
  • Slow or delayed growth
  • Weak bones

Children born with alpha thalassemia major and beta-thalassemia major (Cooley’s anemia) usually develop severe anemia early, during the first year of life. They may also experience these thalassemia symptoms:

  • Poor appetite
  • Yellowish skin (jaundice)
  • Dark urine
  • Irregular facial bone structure
  • Intellectual or developmental disabilities

New York Presbyterian hematologists are well-versed in all of these thalassemia types and can steer you toward the best treatments.

What Causes Thalassemia?


Thalassemia is an inherited blood disorder. It occurs when gene mutations prevent your body from making the right amount of alpha globin or beta globin chains. As a result, your body doesn’t make enough hemoglobin. It also makes fewer red blood cells, which are then not able to deliver enough oxygen throughout your body.

If you inherit at least one normal gene from one parent, you’re a “carrier.” Most carriers don’t have symptoms, or just experience mild anemia. But if you inherit two or more gene mutations, your disease will be more serious.

Risk Factors

Risk Factors

Your risk of thalassemia is based on the following:

  • Your family history. If one or both parents have mutations in the alpha globin or beta globin genes, their child can develop thalassemia. Even if you don’t show any signs of the disease, you can still be a silent carrier.
  • Race or ethnicity. People of Asian, Italian, Greek, Middle Eastern, and African descent are more likely to have thalassemia.



If your child has thalassemia, it is very important that they receive proper treatment. There are many different complications that can occur from thalassemia, including the following:

  • Infections. People with thalassemia are at increased risk of certain infections if their spleen has been removed.
  • Iron overload. Patients may become iron overloaded, especially if they require regular blood transfusions. This can damage organs and tissues. As a result, patients require careful monitoring.
  • Bone deformities. People with thalassemia may have overactive bone marrow, which may make bones thin and brittle and raises the risk of developing osteoporosis. It can also widen bones in your face and skull.
  • Enlarged spleen. When the spleen breaks down red blood cells in someone with thalassemia, the iron may stay inside the spleen. Thalassemic red blood cells may also get stuck in the spleen.
  • Pulmonary hypertension. This may be a complication of low hemoglobin levels.
  • Heart failure. Untreated anemia can lead to a heartbeat that is too fast as the body tries to compensate for lack of oxygen. Over time, this can enlarge the heart. On the flip side, iron overload may lead to too much iron being deposited in the heart.
  • Diabetes. The main cause of diabetes linked to thalassemia is iron overload. People have a higher risk if they also are overweight, sedentary, have high blood pressure, or liver disease.
  • Liver disease. Iron overload can cause iron to settle in the liver, leading to damage.



There is no way to prevent thalassemia since it is a genetic condition. If you plan to have children and you or your partner have a family history of thalassemia, you may want to meet with a genetic counselor. They can order a blood test to see if either of you are carriers of this condition.

If you or your partner do carry a defective gene, a genetic counselor can advise you of your risk of having a baby with thalassemia. New York Presbyterian can help with genetic testing and family planning if one or both parents is a carrier of this disease. One option is in vitro fertilization (IVF) in combination with another procedure called preimplantation genetic testing (PGT). This tests embryos for gene mutations and only implants those without them.

Get Care

Trust NewYork-Presbyterian for Thalassemia Care

The teams at our children’s hospitals understand the toll a chronic disease like thalassemia can take on patients and their families. We provide the most effective and individualized treatment regimens available for thalassemia, along with periodic monitoring for possible complications.

Our teams include pediatric hematologists with expertise in thalassemia, nurses, child life specialists, social workers, and genetic counselors. We work closely with cardiologists, nephrologists, gastroenterologists, endocrinologists, fertility experts, orthopedists, and bone specialists to ensure your child’s life is the best.