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Hemoglobin S–Beta-Thalassemia Disease


Evan M. Braunstein

, MD, PhD, Johns Hopkins University School of Medicine

Last full review/revision Sep 2020| Content last modified Sep 2020
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Beta globin mutations may result in partial loss (beta + allele) or complete loss (beta 0 allele) of beta globin function. Thus, manifestations of S-beta-thalassemia depend on whether the patient has a beta + or beta 0 allele. Those with beta + produce varying amounts of beta globin (and thus have varying amounts of Hb A). Those with beta 0 produce no beta globin and thus have no Hb A.

Clinically, manifestations depend on the amount of Hb A. Thus, Hb-S-beta 0 thalassemia manifests similarly to sickle cell disease (Hb SS), whereas Hb S–beta+ thalassemia causes symptoms of moderate anemia and some signs of sickle cell disease Symptoms and Signs Sickle cell disease (a hemoglobinopathy) causes a chronic hemolytic anemia occurring almost exclusively in blacks. It is caused by homozygous inheritance of genes for hemoglobin (Hb) S. Sickle-shaped... read more Symptoms and Signs , which are usually less frequent and less severe than those of pure sickle cell disease. Mild to moderate microcytic anemia is usually present along with some sickled red blood cells on stained blood smears.

Diagnosis requires quantitative hemoglobin studies. Hb S predominates on electrophoresis and is always greater than 50%.Hb A is decreased Hb-S-beta + or absent in Hb-S-beta 0. Hb F increase is variable.

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