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.

Full text of GeneReview (by section):

Summary

GeneReview Scope

Diagnosis

Clinical Characteristics

Genetically Related (Allelic) Disorders

Differential Diagnosis

Management

Genetic Counseling

Resources

Molecular Genetics

Chapter Notes

References

Authors:

Arielle L Langer

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