β-thalassemia results from a decrease in the synthesis of beta polypeptide chains as a result of a mutation or deletion in the β-globin gene, and the synthesis of hemoglobin A is disrupted.
There are two β-globin genes, and patients may have heterozygous, homozygous, or severely heterozygous mutations.
The clinical signs of thalassemias are similar, but the severity varies depending on the amount of normal hemoglobin.
Passing on a mutated gene is usually asymptomatic or has mild symptoms. It is called thalassemia minor or Betta thalassemia.
The passing of two mutated genes manifests itself with serious symptoms. It is called thalassemia major or Cooley's anemia.
