What is thalassemia?

Thalassemia is the name given to a group of hereditary red blood cell disorders that affect hemoglobin production. Thalassemias are among the most common inherited disorders in the world: the affect more than 300,000 children worldwide, particularly in areas where malaria is common, including the Mediterranean and Middle East regions, Sub-Saharan Africa, the Indian subcontinent and Southeast Asia. [1] [2]

Hereditary

Inherited by an offspring from their parent/s.

1. Weatherall, D.J. (2012). The definition and epidemiology of non-transfusion-dependent thalassemia. Blood Reviews 26 Suppl 1: S3–6.

2. Cao, A. & Kan, Y.W. (2013). The Prevention of Thalassemia. Cold Spring Harbor Perspectives in Medicine 3. Accessed from

External link

Causes and types

Hemoglobin is a very important component in red blood cells, as it carries oxygen around the body. Hemoglobin is comprised of four sub-units: two alpha-globin sub-units (alpha1 and alpha2) and two beta-globin sub-units (beta1 and beta2). These components are created by specific genes that are passed onto the child from each parent. Sometimes genes can become mutated or deleted and therefore do not allow the regular production of hemoglobin. This leads to red blood cells that are poorly formed, with a shortened life span, anemia and a lack of oxygen transported to all parts of the body.

Red blood cells, haemoglobin molecule and oxygen molecules.Healthy red blood cells use hemoglobin to carry oxygen. 

Thalassemia is a hereditary condition caused by gene mutations or deletions that are passed on from your mother or father, or both. An estimated 5% of the world's population carries one of these mutations. [3 ] Depending on the number and type of mutated genes or deleted genes, varying types of thalassemia are caused.

Alpha thalassemia

Alpha thalassemia involves the deletion of between one and four of the genes required to make alpha-globin.

Alpha thalassemia carrier

Of the four possible genes used for making alpha-globin, a person has either one or two deleted genes, but is healthy. These people are called 'carriers' and they have a risk of giving birth to a child affected with either hemoglobin H disease or Bart's hydrops fetalis (see below) if their partner is also a carrier.

Hemoglobin H disease

Of the four possible genes used for making alpha-globin, individuals have three deleted genes and require regular medical care. This can include mild to moderate anemia that requires lifelong treatment with intermittent blood transfusion.

Bart's hydrops fetalis

None of the four genes needed to make alpha-globin are present. This means that hemoglobin cannot be formed and oxygen cannot be transported around the body. This often results in death before birth.

Beta thalassemia

Beta thalassemia involves the mutation of one or two of the genes needed to make beta-globin. There are two forms of beta thalassemia.

Beta thalassemia minor

People with beta thalassemia minor have a mutation in one gene used for making beta-globin. These individuals are healthy and are called carriers. If you have Beta thalassemia minor and your partner is also a carrier, there is a risk of having a child affected beta thalassemia major. There is a risk of having a child affected with beta thalassemia major if their partner is also a carrier.

Beta thalassemia major

Individuals with beta thalassemia major have mutations in both genes used for making beta-globin. This results in severe anemia that requires lifelong treatment.

Anemia

A deficiency in red blood cells or hemoglobin in the body.

Genes

A unit of inheritance (heredity) of a living organism. A segment of genetic material, typically DNA, that specifies the structure of a protein or related molecules. Genes are passed on to offspring so that traits are inherited, making you who you are and what you look like.

Hereditary

Inherited by an offspring from their parent/s.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Risk factors

As thalassemia is an inherited condition, risk factors are associated with family history. If both parents have the condition or are carriers of the condition, there is an increased risk of giving birth to a child with the condition. Ethnicity can also be a risk factor: Alpha thalassemia is more common among people of Asian descent, while beta thalassemia is more common among people from the Mediterranean, the Middle East, South-East Asia and the Indian subcontinent.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Signs and symptoms

Signs and symptoms associated with thalassemia can include:

  • Weakness;
  • Fatigue;
  • Jaundice;
  • Enlargement of organs, especially the spleen;
  • Slow growth;
  • Failure to thrive;
  • Paleness;
  • Dark urine;
  • Abdominal swelling, and;
  • Deformities of facial bones.

Jaundice

A yellowing of the skin, the whites of the eyes and the mucous membranes, due to an accumulation of bilirubin in the blood. Often a symptom of liver problems.

Spleen

An organ in the abdominal cavity that is involved in filtering out old blood cells and fighting infection.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Methods for diagnosis

Thalassemia is diagnosed by several tests involving the components of your blood.

Full blood examination

This is a simple blood test that examines the red blood cells and other components of blood. Thalassemia may be suspected if there are specific changes in the number, size, shape and color of red blood cells.

Hemoglobin electrophoresis

This test measures the amounts of different forms of hemoglobin in blood. This test can be used to detect most carriers.

DNA analysis

This test can identify which mutations or deletions of hemoglobin genes a person has. This can also be used to detect or confirm carriers.

Genes

A unit of inheritance (heredity) of a living organism. A segment of genetic material, typically DNA, that specifies the structure of a protein or related molecules. Genes are passed on to offspring so that traits are inherited, making you who you are and what you look like.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Types of treatment

The treatment of thalassemia depends on the type and severity of the condition. No treatment is required for carriers of alpha thalassemia or beta thalassemia minor. Hemoglobin H disease and beta thalassemia major are treated with regular blood transfusions. This is done to boost the levels of red blood cells and, most importantly, hemoglobin. Over time, the red blood cells 'wear out' and a new blood transfusion is required. This is an ongoing condition and transfusions will be required for life.

In some cases, bone marrow transplants are also possible and can sometimes result in cure. If successful, the new bone marrow can produce normal blood cells with normal hemoglobin. However, there are significant risks with this procedure, including the possibility of death. Because people with thalassemia can lead normal lives with intermittent blood transfusions, bone marrow transplant may not be considered.

Woman receiving blood transfusion.A blood transfusion. 

Bone marrow

The spongy, vascular or fatty tissue found inside bones, responsible for producing blood cells.

Transfusions

The process of receiving blood or blood components from an external source directly into the bloodstream.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Potential complications

Complications associated with thalassemia can include passing on the condition to a child, if both parents have the condition or are carriers of the condition.

For people requiring regular blood transfusions, there is a side effect of increased iron accumulating in the body. Over time this becomes stored in the liver, heart and pancreas and can lead to liver cirrhosis, heart failure and diabetes. Excess iron can be removed using medications, such as desferrioxamine, in a process called iron chelation.

Thalassemia can cause bone deformities. This occurs because thalassemia causes an expansion of bone marrow, leading to a widening of bones. This can make bones brittle and can cause facial bone structure deformities and slow growth rates in children.

Thalassemia can also cause your spleen to enlarge (splenomegaly). This occurs because your spleen must work harder to filter and remove damaged blood cells. Sometimes the spleen can become too large and must be removed.

Bone marrow

The spongy, vascular or fatty tissue found inside bones, responsible for producing blood cells.

Cirrhosis

Scarring of liver tissue, which the irreversible replacement of normal liver cells by fibrous cells. Cirrhosis is the result of chronic liver damage.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterized by high blood sugar levels. Also known as diabetes mellitus.

Pancreas

An organ located behind the stomach that secretes insulin and glucagon into the bloodstream and digestive enzymes into the intestines.

Spleen

An organ in the abdominal cavity that is involved in filtering out old blood cells and fighting infection.

Transfusions

The process of receiving blood or blood components from an external source directly into the bloodstream.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Prognosis

Depending on the type of thalassemia, dealing with the condition can be difficult. If you are a carrier, no treatment is required, but there is a risk of having a child with thalassemia if your partner is also a carrier. If you have a more severe form of thalassemia, regular blood transfusions will be required for life. A good network of family and friends can support you with this condition.

Transfusions

The process of receiving blood or blood components from an external source directly into the bloodstream.

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.

Prevention

If you are planning on having a baby, screening is possible to identify if you or your partner are carriers of thalassemia. Screening is particularly important if there is a family history of the condition. This can identify if there is a chance that you will have a child with thalassemia.  

3. Martin, A. & Thompson, A.A. (2013). Thalassemias. Pediatric Clinics of North America 60: 1383–1391.