Glycophorin A mutation Ala65 -> Pro gives rise to a novel pair of MNS alleles ENEP (MNS39) and HAG (MNS41) and altered Wr(b) expression: direct evidence for GPA band 3 interaction necessary for normal Wr(b) expression

We report here a novel Glycophorin A (GPA) mutation Ala65-->Pro which gives rise to a low-incidence antigen HAG, lack of a high-incidence antigen ENEP and aberrant expression of the high-incidence Wr(b) antigen. Anti-ENEP was identified in the serum of a transfused male patient (E.H.) who was homozy gous for a GPA Ala65-->Pro mutation and possessed a novel low-incidence ant igen which we have called HAG. An unrelated MAG-positive individual, hetero zygous for the Ala65-->Pro mutation, has also been identified. Anti-HAG was present in several multispecific antisera to low-incidence antigens and in one monospecific serum. Normal expression of the Wrb antigen depends on the presence of amino acid Glu658 of band 3 and on the presence of GPA. However, a specific epitope on GPA has not previously been implicated. DNA sequence analysis of band 3 fr om patient E.H. was normal in the region of Wr(a)/Wr(b) polymorphism with h omozygous presence of Glu658 and therefore the abnormal Wr(b) expression re sults from the Ala65-->Pro mutation in GPA. The ENEP and HAG antigens have been assigned the MNS blood group system num bers 002.039 and 002.041, respectively, by the ISBT Working Party on Termin ology for Red Cell Surface Antigens.