DYSF and Diamond-Blackfan anemia: Immunostaining for dysferlin in RBC ghosts showed variable levels of dysferlin present in the RBCs of all transfusion-independent DBA patients tested but it was not found on RBCs of transfusion dependent DBA patients (data not shown), indicating that dysferlin is an integral RBC membrane protein and does not derive from white blood cell contamination or from transfer to circulating RBCs by monocytes.