Beta thalassemia is an inherited blood disorder characterized by the abnormal production of a blood protein called hemoglobin. This condition is caused by a mutation within the gene that is responsible for the healthy production of hemoglobin. In healthy people, hemoglobin carries oxygen to tissues and cells throughout the body. Patients with beta thalassemia do not have adequate levels of oxygen within the blood, which can cause anemia. There are two main types of beta thalassemia with symptoms that range from mild to severe. Beta-globin is produced by two genes, one gene from each parent. The severity of the condition correlates with the amount of normal beta-globin production.
Beta Thalassemia Minor
The individuals with thalassemia minor have only one copy of the beta thalassemia gene. These individuals are said to be heterozygous for beta thalassemia and will have mild anemia. This situation can vary closely resemble that with mild iron-deficiency anemia. However, people with thalassemia minor have a normal blood iron level. No treatment is necessary for thalassemia minor. In particular, iron is neither necessary nor advised. Beta Thalassemia Major
The child born with thalassemia major has two genes for beta thalassemia and no normal beta chain gene. The child is homozygous for beta thalassemia. This causes a striking deficiency in beta chain production and in the production of HBA. The clinical picture associated with thalassemia major was first described in 1925 by the American pediatrician Thomas Cooley. Hense, the name Cooley's anemia in his honor. At birth the baby with thalassemia major seems entirely normal. Anemia begins to develop within the first months after birth. It becomes progressively more and more severe.
The gene controlling beta chain production is located on the short (p) arm of chromosome 11 at position 15.5. More precisely, The HBB gene is located from base pair 5,203,271 to base pair 5,204,876 on chromosome 11.
Characteristics of the Disease
Beta thalassema major is characterized by severe anemia that can begin months after birth. In the United States and other developed countries, beta thalassemia is identified and treated early and effectively. In untreated, beta thalassemia major can lead to severe tiredness, jaundice, and growth and developmental delay. The body attempts to compensate by producing more blood cells in the bone marrow. However, this is ineffective without the needed genetic instructions to make enough functioning hemoglobin. Instead, obvious bone expansion and changes occur that cause characteristics facial and other changes in appearance, as well as increased risk of fractures. Severe anemia affects other organs in the body such as the heart, spleen, and liver. This can lead to heart failure and enlargement of the the liver and spleen. When untreated, beta thalassemia major generally results in childhood death, usually due to heart failure. Fortunately, in developed countries diagnosis is usually made early, often before symptoms have begun. This allows for treatment with blood transfusion therapy, which can prevent most of the complications of the severe anemia caused by beta thalassemia major.
A compelet blood count will identify low levels of hemoglobin and other red blood cell abnormalities that are characterized with beta thalassemia. Since thalassemia trait can sometimes be difficult to distinguish from iron deficiency, tests to evaluate iron levels are important. A hemoglobin electrophoresis is a test that can help identify the types and quantities of hemoglobin made by an individual. This test uses an electric field applied across a slab of gel-like material. Hemoglobins migrate through this gel at various rates and to specific locations, depending on their size, shape, and electrical charge. In addition, isoelectric focusing and high-performance liquid chromatography (HPLC) use similar principles to...
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