Home Page > Diseases by Region: Ashkenazi > Congenital Amegakaryocytic Thrombocytopenia (CMAT)

Congenital Amegakaryocytic Thrombocytopenia (CAMT)
by Yael Rosenberg, RN

• Description
• Symptoms
• Incidence and Carriers
• Treatment
• Testing
• Screening Laboratories
• Resources & More
• Support Groups

Description
Congenital Amegakaryocytic Thrombocytopenia (CAMT) is an autosomal recessive genetic disorder that is the result of the mutation of the MPL gene on chromosome 1. The onset of this genetic condition is early infancy and is characterized by thrombocytopenia (Low amount of platelets) and absence of megakaryocytes which are the large cells in the bone marrow that produce platelets. In the severe form individual afflicted with this disorder develop life threatening bleeding disorders.

CAMT has three known types:
Type I: Presents with severe, continuous thrombocytopenia and early onset of pancytopenia which is low red and white blood cell count.

Type II: Presents with temporary elevation of platelets in early infancy up to normal values. Onset of bone marrow failure at 3 to 6 years of age or later.

Type III: There is no defect in the MPL gene but there is ineffective megakaryopoesis (platelet production)

30% of patients with CAMT die of bleeding complications. Individual with CAMT may be at a higher risk for developing myelogenous leukemia.

Symptoms
   • Easy Bruising
   • Bleeding (can be life threatening) can be skin, gastrointestinal, pulmonary, intracranial
   • Petechiae (small round spot of bleeding in skin or mucous membranes)
   • Impaired blood clotting
   • Diminished platelet count

Incidence and Carriers
Carrier Frequency: 1 in 75 in Jews of Ashkenazi descent
Disease Frequency: 1 in 22,500 in Jews of Ashkenazi descent
The exact prevalence in the general population is unknown and is probably underestimated due to difficult and inconsistent diagnosis of the disease.

Treatment
   • Bone marrow transplantation
   • Platelet transfusions ( low platelet count or preventative)
   • Fibrinolytic inhibitors to manage bleeding symptoms
   • Red blood cell transfusions when and if needed
   • Hematopoietic stem cell transplantation

Testing
   •  Bone marrow examination
   • Complete blood count
   • Genetic Testing for the MPL gene mutation