A very rare congenital disorder combining hypomegakaryocytic thrombocytopenia and bilateral absence of radii (thumbs are not missing) due to mutations in the RBM8A gene. Patients present with reduced blood platelets or megakaryocytes, and episodes of bleeding (petechiae, nosebleed, ecchymosis, hemorrhage) that may become life-threatening in early life. Thrombocytopenia can become less severe as the infant ages. Other findings include short stature, distinct facial features (micrognathia, broad forehead, low-set and rotated ears), hypoplasia of limbs, and kidney and heart abnormalities. Frequently patients present with failure to thrive and persistent diarrhea due to cow milk intolerance.

Treatment involves management of early symptoms of thrombocytopenia and, if severe, platelet transfusion. Other symptoms may be treated with surgery, physical therapy, and dietary management.