Congenital amegakaryocytic thrombocytopenia-2 (CAMT2) is an autosomal recessive disorder characterized by thrombocytopenia with progression to pancytopenia, aplastic anemia, and bone marrow failure. Serum THPO is decreased or inappropriately normal, and bone marrow is hypocellular with decreased or absent megakaryocytes. Most patients present in infancy or early childhood and have a severe disease course, whereas some have later onset and milder symptoms. Bone marrow transplant is ineffective because the defect is extrinsic to hematopoietic cells. Treatment with THPO receptor (MPL; 159530) agonists results in clinical improvement and restoration of trilineage hematopoiesis (Dasouki et al., 2013; Seo et al., 2017).
For a discussion of genetic heterogeneity of CAMT, see CAMT1 (604498). [from
OMIM]