Beta-thalassemia is an inherited disorder of the blood that affects the hemoglobin inside red blood cells. The condition is caused by an abnormality in the production of the beta globin chain found in hemoglobin. This results in haemoglobin that has a reduced capacity to transport oxygen around the body, which can lead to symptoms of anemia.
Beta thalassemia statistics
In the UK, the majority of beta-thalassemia cases occur in individuals of Mediterranean, Middle Eastern and particularly South Asian origin, with 80% of babies with the condition born to parents of Indian, Bangladeshi and Pakistani descent.
Globally there are around 80 to 90 million people (1.5% of the total population) that are carriers of beta thalassemia and 60,000 symptomatic children born each year.
Types of beta thalassemia
There are several sub-categories of beta thalassemia. These include:
- Beta thalassemia major
- Beta thalassemia intermedia
- Beta thalassemia minor
Two genes are involved in coding for beta globin, with one gene inherited from each parent. Beta thalassemia is caused by mutations in these genes.
If one of the genes inherited is mutated, symptoms are mild and this form of the condition is referred to as beta thalassemia minor. If both of the genes inherited are mutated, moderate-to-severe symptoms will develop.
The most severe form of the condition is referred to as thalassemia major. Individuals with this condition will need to have blood transfusions for their entire life. However, the inheritance of two defective genes can also lead to a milder form of the condition and this is referred to as beta thalassemia intermedia.
Beta thalassemia major
Individuals with beta thalassemia major usually develop symptoms within the first two years of life. The infant may fail to thrive and often has difficulty feeding, tires easily and suffers from severe anemia. The infant may also suffer from diarrhea, irritability, recurrent episodes of fever, and other intestinal problems. These children have trouble gaining weight and growing at the rate expected for their age. Other complications include enlarged spleen, heart and liver and misshapen bones.
In many cases, regular blood transfusions are required to replenish the blood with healthy red blood cells. However, these regular transfusions can lead to a build up of iron in the blood that can damage the heart, liver and endocrine system and chelation therapy may be needed to remove this iron from the body.
Beta thalassemia intermedia
The symptoms of thalassemia intermedia are milder than those of thalassemia major and often manifest later in life. Such individuals may have mild-to-moderate anemia and growth abnormalities. Often patients do not require transfusions when they are younger but may need to start them when they are older.
Beta thalassemia minor
This form of thalassemia usually gives rise to mild symptoms but patients do not require blood transfusion. Although this condition is not life threatening, quality of life may be affected by mild-to-moderate anemia. This form of the condition is also referred to as beta thalassemia trait.
Sometimes, individuals inherit one gene for beta thalassemia from one parent as well as a gene for sickle hemoglobin (hemoglobin S) from the other parent. This is called sickle-beta thalassemia and can present with similar symptoms to sickle cell disease such as pain, fatigue, an enlarged spleen and vulnerability to infections.
Reviewed by Sally Robertson, BSc