Congenital Amegakaryocytic Thrombocytopenia

Congenital Amegakaryocytic Thrombocytopenia (CAMT) is an inherited bone marrow failure disorder that begins in infancy. In this disease, the blood producing cells in the bone marrow do not produce platelets, which are important for blood clotting, or megakaryocytes, which are responsible for producing platelets. This means the child's blood will not clot properly after bleeding. Over time, the bone marrow may stop making red blood cells and neutrophils. The symptoms for CAMT, such as bruising and bleeding, can be life threatening. Intellect is not affected by CAMT. Currently, the only treatment for CAMT is bone marrow transplantation. CAMT is caused by pathogenic variants in the MPL gene.

CAMT is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for CAMT. However, the risk to have a child affected with CAMT is increased. Testing of reproductive partners is recommended for carriers of CAMT.

CAMT is a very rare genetic condition and it is unknown how often it occurs. Only a limited number of cases have been reported since the initial report of this disease.

Seattle Cancer Care Alliance: Congenital Amegakaryocytic Thrombocytopenia (CAMT) (http://www.seattlecca.org/diseases-treatments.cfm)

OMIM [AMEGAKARYOCYTIC THROMBOCYTOPENIA, CONGENITAL: 604498] (http://www.ncbi.nlm.nih.gov/omim)

• Full gene sequencing