The glycophorin (GP) molecule associated with the GP.Dane phenotype is a GP(A-B-A) hybrid that contains some amino acids encoded by the Pseudoexon 3 of GYPB and Asn45 of GPA and carries the low-prevalence MNS antigens DANE and Mur. Serum from a woman of English ancestry contained an immunoglobulin M alloantibody to a high-prevalence MNS antigen, and the purpose of this study was to identify the molecular basis of her phenotype.STUDY DESIGN AND METHODS
Hemagglutination, Western blotting, and DNA analyses were performed by standard methods.RESULTS
Tests of the proband's RBCs with monoclonal antibodies indicated a change of amino acids between positions 27 and 55 of GPA. Her RBCs expressed M, s, Mur, and DANE antigens and were Mg-negative. The antigen recognized by her antibody was sensitive to treatment with papain, ficin, and trypsin and resistant to α-chymotrypsin and dithiothreitol. Sequencing of DNA from the proband revealed a sequence of nucleotides identical to the GYP(A-B-A) encoding GP.Dane but without the adenyl nucleotide substitution, which has been predicted to change Ile46 of GPA to Asn45. Testing of her immediate family revealed the presence of an Mk gene.CONCLUSION
The proband had a novel GYP(A-B-A) encoding a DANE+ GP that is in cis to GYPBs and in trans to Mk. The high-prevalence antigen lacking from this GP.Dane phenotype and recognized by the proband's serum is called ENDA (ISBT Number MNS44). Our results indicate that the change of Ile46 of GPA to Asn45 of GP.Dane is not required for expression of the DANE antigen.