Beta thalassemia describes a condition of the blood characterized by abnormal hemoglobin in the red blood cells. This abnormal hemoglobin is reduced in its capacity to transport oxygen around the body, which leads to anemia, fatigue, weakness and shortness of breath.
Each molecule of hemoglobin is made up of one pair of alpha chain proteins and one pair of beta chain proteins. Beta thalassemia is caused by mutations in the genes that code for the beta chain protein.
Types of beta thalassemia
Two genes are involved in coding for the beta globin protein, with one inherited from each parent. If one gene inherited is mutated, symptoms are mild and this form of the condition is referred to as beta thalassemia minor.
If two mutated genes are inherited, 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 the duration of their lifetime. However, a milder form of the disease can also develop when two genes have been inherited and this is referred to as beta thalassemia intermedia.
Cause and inheritance
As an inherited disorder, beta thalassemia can only be passed on genetically. Individuals with one defective gene are termed carriers of the condition and may be at risk of having a child affected the illness if their partner is also a carrier of the faulty gene. In these cases, genetic testing is advised to assess the likelihood of a child being born with the disease.
Who is at risk?
Most cases of beta thalassemia occur in individuals of Middle Eastern, Mediterranean, and South-East Asian origin. In the UK, 80% of babies with the condition are born to parents of Pakistani, Bangladeshi or Indian origin.
Treatment often is not needed for mild beta thalassemia. For more severe forms of the condition, the only cure is transplant, either bone marrow transplant or cord blood transplant. However, both procedures carry a risk of complications and are not always suitable for patients.
In beta thalassemia major, regular blood transfusions are required, sometimes every few weeks. 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 form the body.
Reviewed by Sally Robertson, BSc