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Amegakaryocytic Thrombocytopenia (Amega)

These patients have bruising during the first year of life, due decreased production of platelets by the bone marrow (platelets are the cells which help the blood to clot). The physical appearance is otherwise normal. The gene for Amega has been identified. It is called MPL. Males and females are affected equally.

  1. What are the major findings on physical examination?
    1. Bruises, bleeding, tiny spots of bleeding into the skin ("petechiae")

  2. What is the age at diagnosis?
    1. From birth to 9 years
    2. The diagnosis is usually made by 1 month of age.

  3. What is the pattern of bone marrow failure?
    1. The bone marrow problems typically start with a low platelet count.
    2. Patients may eventually develop aplastic anemia when all 3 types of cells (red cells, white cells and platelets) are abnormally low because the bone marrow is not producing them.

  4. What specific kinds of cancer develop?
    1. Leukemia (cancer of the blood and bone marrow)

  5. How is Amega specifically diagnosed?
    1. Characteristic medical history
    2. Mutation analysis (genetic testing)
      1. Laboratories can now identify the genetic "error" (mutation) in some patients, which occurs in the gene called MPL.
      2. The disease occurs only if a person has two abnormal (mutant) genes. The inheritance is therefore thought to be of the autosomal recessive type.
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