Glycolipids and glycopeptides of red cell membranes in congenital dyserythropoietic anaemia type II (CDA II).

The composition and structure of neutral and acidic oligoglycosylceramides, polyglycosylceramides and polyglycosylpeptides were determined in erythrocyte membranes of two patients with congenital dyserythropoietic anaemia type II. In keeping with previous studies we found an elevated accumulation in CDA II erythrocytes of LacCer, Lc3Cer and nLc4Cer. Gb4Cer was elevated in erythrocytes of only one of the two patients tested. In addition we found a significant increase of 6IVNeuAcnLc4Cer ganglioside. Polyglycosylceramides were elevated 6-fold but they resembled those of cord erythrocytes with respect to complexity and the number of side chains. Polyglycosylpeptides of CDA II erythrocytes were decreased 7-fold. These glycopeptides were, however, heterogeneous with respect to branching pattern; the minor fraction was highly branched whereas the major one was more linear in structure. Both polyglycosylceramides and polyglycosylpeptides exhibited high I and i antigenicity. We postulate that the accumulation of glycolipids and underglycosylation of glycoproteins in CDA II membranes results from the prolongation of G1 and possibly M phases of the mitotic cycle of the erythroid cells in which glycolipids are preferentially synthesized.