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Diseases

Genetic and Rare Diseases Information Center (GARD)

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Beta-thalassemia


Other Names for this Disease

  • Beta thalassemia intermedia
  • Beta thalassemia major
  • Beta thalassemia minor
  • Cooley's anemia
  • Erythroblastic anemia
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Inheritance

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How is beta-thalassemia inherited?

Beta-thalassemia major and beta-thalassemia intermedia are usually inherited in an autosomal recessive pattern, which means both copies of the HBB gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene (referred to as carriers), but they typically do not show signs and symptoms of the condition. When two people who are carriers of an autosomal recessive condition have a child, there is a 25% (1 in 4) chance that the child will have the condition, a 50% (1 in 2) chance that the child will be a carrier like each of the parents, and a 25% (1 in 4) chance that the child will not have the condition and not be a carrier.[1]

Sometimes, people with only one HBB gene mutation in each cell (carriers) develop mild anemia. These people are said to have beta-thalassemia minor or beta-thalassemia trait. Therefore, each time two individuals with beta-thalassemia minor have a child, there is a 25% chance that each child will have either beta-thalassemia major or intermedia (depending on the severity of that child's symptoms), a 50% chance that the child will be a carrier without symptoms or have beta-thalassemia minor (depending on whether the child has anemia), and a 25% chance that the child will not have beta-thalassemia and not be a carrier for the condition.[1]

In a small percentage of families, the HBB gene mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is enough to cause the signs and symptoms of beta-thalassemia.[1]
Last updated: 7/7/2011

References
  1. Beta thalassemia. Genetics Home Reference. July 2009; http://ghr.nlm.nih.gov/condition/beta-thalassemia. Accessed 7/7/2011.


Other Names for this Disease
  • Beta thalassemia intermedia
  • Beta thalassemia major
  • Beta thalassemia minor
  • Cooley's anemia
  • Erythroblastic anemia
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.