Two genes are involved in making the beta-globin part of hemoglobin -- one from each parent. Beta thalassemia occurs when one or both of the two genes are variant. Examples of beta thalassemia include:
If one gene is affected, a person is a carrier and has mild anemia. This condition is called beta thalassemia trait or beta thalassemia minor.
If both genes are variant, a person may have moderate anemia (beta thalassemia intermedia or mild Cooley's anemia) or severe anemia (beta thalassemia major or Cooley's anemia).
Thalassemia Inheritance: What's the Risk?
If two people with beta thalassemia trait (carriers) have a baby, one of three things can happen:
The baby could receive two normal genes (one from each parent) and have normal blood (1 in 4 chance)
The baby could receive one normal gene from one parent and one variant gene from the other parent, and have thalassemia trait (2 in 4 chance)
The baby could receive two thalassemia genes (one from each parent) and have a moderate to severe form of the disease (1 in 4 chance).
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