THE CISTERNAE DECORATING THE RED-BLOOD-CELL MEMBRANE IN CONGENITAL DYSERYTHROPOIETIC ANEMIA (TYPE-II) ORIGINATE FROM THE ENDOPLASMIC-RETICULUM

We studied 20 individuals from 17 unrelated families with congenital d yserythropoietic anemia (type II; CDAII). The clinical phenotype was m ild to moderate. The inheritance pattern was invariably recessive. Coo massie blue stained gels after sodium dodecyl sulfate-polyacrylamide g el electrophoresis (SDS-PAGE) show that band 3 was thinner and migrate d slightly faster than usual. In addition, staining showed two unknown minor bands (in the patients), but not in normal controls, the obliga te carrier parents, or in patients with other anemic syndromes. These minor proteins were studied using partial digestion, amino acid sequen cing, Western blotting, immunofluorescence, and immunogold electron mi croscopy. They were identified as the glucose-regulated protein GRP78 and calreticulin that are resident proteins of the endoplasmic reticul um (ER). Using specific antibody, we showed that protein disulfide iso merase (PDI), a third major protein of the ER, was also present on the SDS-PAGE of red blood cell (RBC) ghosts. Immunofluorescence colocaliz ed PDI with the dense discontinuous ring decorating the RBC membrane. immunogold electron microscopy showed that PDI was localized in the lu men of the cisternae, confirming that these originate from the smooth ER. From a practical point of view, screening the above minor proteins in RBC membranes appears to be a straightforward and reliable diagnos tic test for CDAII. (C) 1996 by The American Society of Hematology.