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Beta-thalassemia HBB/LCRB

MedGen UID:
Concept ID:
Disease or Syndrome
Synonyms: beta-thalassemia; beta-thalassemia HBB/LCRB; thalassemia, beta; thalassemia, hispanic gamma-delta-beta
Genes (locations): HBB (11p15.4); HBB-LCR (11p15.4)
Monarch Initiative: MONDO:0013517
OMIM®: 613985

Disease characteristics

Excerpted from the GeneReview: Beta-Thalassemia
Beta-thalassemia (β-thalassemia) has two clinically significant forms, β-thalassemia major and β-thalassemia intermedia, caused by absent or reduced synthesis of the hemoglobin subunit beta (beta globin chain). Individuals with β-thalassemia major present between ages six and 24 months with pallor due to severe anemia, poor weight gain, stunted growth, mild jaundice, and hepatosplenomegaly. Feeding problems, diarrhea, irritability, and recurrent bouts of fever may occur. Treatment with regular red blood cell transfusions and iron chelation therapy allows for normal growth and development and improves prognosis. Long-term complications associated with iron overload include stunted growth, dilated cardiomyopathy, liver disease, and endocrinopathies. Individuals with β-thalassemia intermedia have a more variable age of presentation due to milder anemia that does not require regular red blood cell transfusions from early childhood. Additional clinical features may include jaundice, cholelithiasis, hepatosplenomegaly, skeletal changes (long bone deformities, characteristic craniofacial features, and osteoporosis), leg ulcers, pulmonary hypertension, extramedullary masses of hyperplastic erythroid marrow, and increased risk of thrombotic complications. Individuals with β-thalassemia intermedia are at risk for iron overload secondary to increased intestinal absorption of iron as a result of dysregulation of iron metabolism caused by ineffective erythropoiesis. [from GeneReviews]
Arielle L Langer   view full author information

Additional description

Beta-thalassemia is characterized by a reduced production of hemoglobin A (HbA, alpha-2/beta-2), which results from the reduced synthesis of beta-globin chains relative to alpha-globin chains, thus causing an imbalance in globin chain production and hence abnormal erythropoiesis. The disorder is clinically heterogeneous (summary by Ottolenghi et al., 1975). Absence of beta globin causes beta-zero-thalassemia. Reduced amounts of detectable beta globin causes beta-plus-thalassemia. For clinical purposes, beta-thalassemia is divided into thalassemia major (transfusion dependent), thalassemia intermedia (of intermediate severity), and thalassemia minor (asymptomatic, carrier state). The molecular and clinical aspects of the beta-thalassemias were reviewed by Olivieri (1999). The remarkable phenotypic diversity of the beta-thalassemias reflects the heterogeneity of mutations at the HBB locus, the action of many secondary and tertiary modifiers, and a wide range of environmental factors (Weatherall, 2001). For a review of beta-thalassemia, see Taher et al. (2021).  http://www.omim.org/entry/613985

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