of an alteration in glycosylation of glycophorin C: an A to G transition at nucleotide 23 results in an asparagine residue instead of the normal serine residue with the resultant loss of glycosylation. The antigen is known as GPC Wb. Duch antigen The rare Duch (Dh) antigen was discovered in Aarhus, Denmark (1968) and is also found on glycophorin C. It is due to a C to T transition at nucleotide 40 resulting in the replacement of leucine by phenylalanine. This antigen is sensitive to trypsin but resistant to chymotrypsin and Endo F. Lewis antigen The Lewis II (Ls(a); Ge-6) antigen has insert of 84 nucleotides into the ancestral GPC gene: the insert corresponds to the entire sequence of exon 3. Two subtypes of this antigen are known: beta Ls(a) which carries the Ge3 epitope and gamma Ls(a) which carries both the Ge2 and Ge3 epitopes. This antigen is also known as the Rs(a) antigen. Ahonen antigen The Ahonen (Ana) antigen was first reported in 1972. The antigen is found on glycophorin D. This antigen was discovered in a Finnish man on May 5, 1968, during post operative blood cross matching for an aortic aneurism repair. In Finland the incidence of this antigen was found to be 6/10,000 donors. In Sweden the incidence was 2/3266 donors. The molecular basis for the origin of this antigen lies within exon 2 where a G->T substitution in codon 67 (base position 199) converts an alanine to a serine residue. While this epitope exists within glycophorin C there it is a cryptantigen. It is only antigenic in glycophorin D because of the truncated N terminus. Others A duplicated exon 2 has erythrocytes also been reported in Japanese blood donors (~2/10,000). This mutation has not been associated with a new antigen. Antibodies Antibodies to the Gerbich antigens have been associated with transfusion reactions and mild hemolytic disease of the newborn. In other studies naturally occurring anti-Ge antibodies have been found and appear to be of no clinical significance. Immunological tolerance towards Ge antigen has been suggested. Other areas High expression of glycophorin C has been associated with a poor prognosis for acute lymphoblastic leukaemia in the Chinese. Glycophorin C is the receptor for the protein erythrocyte binding antigen 140 (EBA140) of Plasmodium falciparum. This interaction mediates a principal invasion pathway into the erythrocytes. The partial resistance of erythrocytes lacking this protein to invasion by P.