Glycoconjugate abnormalities in patients with congenital dyserythropoieticanaemia type I, II and III

Congenital dyserythropoietic anaemia type II (CDA II) is well known for gly cosylation abnormalities affecting erythrocyte membrane glycoconjugates tha t encompass hypoglycosylation of band 3 glycoprotein and accumulation of gl ycosphingolipids: lactotriaosylceramides, neolactotriaosylceramide and poly glycosylceramides. These abnormalities were not observed in erythrocytes fr om patients with CDA of either type I or III. Recently, however, we have de scribed a CDA type I patient in Poland with identical, though less pronounc ed, glycoconjugate abnormalities to those observed in patients with CDA typ e II. The abnormalities included partial unglycosylation of O-linked glycos ylation sites in glycophorin A. These abnormalities are now reported in thr ee Bedouin patients from Israel with CDA type I. In addition, the erythrocy te membranes of these patients exhibited highly increased globotetraosylcer amide content. Glycoconjugate abnormalities were also present in erythrocyt e membranes from three patients from Northern Sweden with CDA type III but they almost exclusively affected glycosphingolipids. In erythrocytes of all patients examined including one with CDA type II, polyglycosylceramides we re significantly hypoglycosylated although, on a molar basis, their content s in erythrocyte membranes were increased. Thus, glycoconjugate abnormaliti es of varying intensity occur in erythrocyte membranes from all patients wi th CDA that were investigated.