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Diseases » Thalassemia » Inheritance

Inheritance and Genetics of Thalassemia

Inheritance of Thalassemia:

Autosomal recessive diseases are usually inherited from both parents who are both usually symptom-free genetic carriers (i.e. neither has the disease). See inheritance of autosomal recessive diseases.

Genetics of Thalassemia:

Thalassemia is a genetic disease that exhibits autosomal recessive inheritance, although there are some exceptions.

Racial Patterns for Thalassemia:

Race Profile for Thalassemia: Common in people of Italian or Greek descent. Also Mediterranean, North African or South-East Asians.

Thalassemia: Inheritance and Genetics Details

Inheritance properties of Thalassemia:

  Disease inherited from: Usually both parents who are symptom-free genetic carriers of Thalassemia; see inheritance of autosomal recessive diseases.

  Gender bias in inheritance: Male or females get the disease equally.

Inheritance Patterns

Inheritance odds for Thalassemia:

  Overall odds of inheritance: Usually both parents who are symptom-free genetic carriers of Thalassemia; see inheritance of autosomal recessive diseases.

  Sibling of diseased child odds of inheriting disease: 25% usually for an autosomal recessive disease.

  Inheritance from one diseased parent odds: Usually 0% chance of disease, 100% chance of being a genetic carrier if one parent has an autosomal recessive disease (not just carrier).

  Inheritance from two diseased parents odds: 100%. Rare case where both parents are not carriers but actually have the autosomal recessive disease.

Genetic Carriers

Genetic carriers of Thalassemia:

  Inheritance from one carrier parent odds: 0% approximately (cannot usually inherit the disease from one parent only).

  Inheritance from two carrier parents odds: 25% disease, 50% chance carrier, 25% neither for autosomal recessive diseases.

Inheritance Features

Inheritance features for Thalassemia:

  Inheritance pattern: Inheritance patterns for autosomal recessive diseases tend to be "horizontal".

  Sporadic form of disease possible?: Very unlikely.

Thalassemia: Genetics Information

Genetics of Thalassemia: Deletions of HBA1 and/or HBA2 tend to underlie most cases of a-thalassemia. The severity of symptoms depends on how many of these genes are lost. Loss of one or two genes is usually asymptomatic, whereas deletion of all four genes is fatal to the unborn child.

In contrast, over 100 types of mutations affect HBB, and deletion mutations are rare. Splice mutations and mutations that occur in the HBB gene promoter region tend to cause a reduction, rather than a complete absence, of b-globin chains and so result in milder disease. Nonsense mutations and frameshift mutations tend to not produce any b-globin chains leading to severe disease. (Source: Genes and Disease by the National Center for Biotechnology)

About inheritance and genetics:

Inheritance of Thalassemia refers to whether the condition is inherited from your parents or "runs" in families. The level of inheritance of a condition depends on how important genetics are to the disease. Strongly genetic diseases are usually inherited, partially genetic diseases are sometimes inherited, and non-genetic diseases are not inherited. For general information, see Introduction to Genetics.


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