Beta-thalassemia classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Maryam Hadipour, M.D.[2]
Overview
Beta-Thalassemia is classified based on the severity and the type of responsible mutation. It mainly has 3 types: β thalassemia minor, β thalassemia major, Thalassemia intermedia. There are less common types such as E/Beta-thalassemia, autosomal dominant Beta-thalassemia and atypical Beta-Thalassemia.
Classification
Beta-Thalassemia is classified based on the severity, dependency on blood transfusions, and the mutation responsible for the disease. Any given individual has two β globin alleles [1]:
| Name | Description | Alleles |
|---|---|---|
| β thalassemia minor (sometimes called β thalassemia trait) | If only one β globin allele bears a mutation. This is a mild microcytic anemia. Detection usually involves measuring the mean corpuscular volume (size of red blood cells) and noticing a slightly decreased mean volume than normal. The patient will have an increased fraction of Hemoglobin A2 (>2.5%) and a decreased fraction of Hemoglobin A (<97.5%). | β+/β or βo/β |
| β thalassemia major or Cooley's anemia | If both alleles have thalassemia mutations. This is a severe microcytic, hypochromic anemia. Untreated, this progresses to death before age twenty. Treatment consists of periodic blood transfusion; splenectomy if splenomegaly is present, and treatment of transfusion-caused iron overload. Cure is possible by bone marrow transplantation. | β+/β+ or βo/βo |
| Thalassemia intermedia | A condition intermediate between the major and minor forms. Affected individuals can often manage a normal life but may need occasional transfusions e.g. at times of illness or pregnancy, depending on the severity of their anemia. | β+/β+ or βo/β |
Note that β+/β+ can be associated with β thalassemia minor or β thalassemia intermedia.
There are other types of beta-thalassemia which are not as common as the above:
- E/Beta-thalassemia: It is another term in which a special mutation in Beta-globin is combined with Beta-thalassemia. Its symptoms and clinical severity can range from mild to severe [2].
- Autosomal dominant Beta-thalassemia: Beta-thalassemia is an inherited autosomal recessive disease, while one variant might happen with a mutation that causes autosomal dominant disease.
- Atypical Beta-Thalassemia: It might happen due to rare mutations that do not match with previously mentioned classifications. When having no symptoms and being detected through genetic testing, the state would be named a silent carrier [3].
References
- ↑ Pines M, Sheth S (April 2023). "Clinical Classification, Screening, and Diagnosis in Beta-Thalassemia and Hemoglobin E/Beta-Thalassemia". Hematol Oncol Clin North Am. 37 (2): 313–325. doi:10.1016/j.hoc.2022.12.003. PMID 36907605 Check
|pmid=value (help). - ↑ Viprakasit V, Ekwattanakit S (April 2018). "Clinical Classification, Screening and Diagnosis for Thalassemia". Hematol Oncol Clin North Am. 32 (2): 193–211. doi:10.1016/j.hoc.2017.11.006. PMID 29458726.
- ↑ Figueiredo MS (2015). "The compound state: Hb S/beta-thalassemia". Rev Bras Hematol Hemoter. 37 (3): 150–2. doi:10.1016/j.bjhh.2015.02.008. PMC 4459467. PMID 26041415.