Amegakaryocytic thrombocytopenia congenital amegakaryocytic thrombocytopenia

Presents in infancy (usually at birth or within 2 months) with profoundly 5 platelets and associated physical signs (petechiae and bruising). Around 40% of affected children also have other congenital abnormalities—chiefly neurologic or cardiac. Developmental delay is common. The marrow completely lacks megakaryocytes and the disorder evolves to severe aplastic anaemia in around 50% of sufferers, usually in the first few years of life. Has none of the unstable DNA features of Fanconi's anaemia (see previous page). Also quite distinct from the syndrome of thrombocytopenia with absent radius (TAR syndrome, see below) since it is a trilineage problem with a much greater mortality. Usually sporadic, but familial cases occur and disorder thought to be inherited. No gene yet identified.

Outlook

Without BMT, mortality from bleeding, infection or (occasionally) progression to leukaemia near 100%.

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