title: The low-frequency MNS blood group antigens Ny(a) (MNS18) and Os(a) (MNS38) are associated with GPA amino acid substitutions.
abstract: BACKGROUND
  Antigens of the MNS blood group system are located on two sialoglycoproteins, GPA and GPB, encoded by GYPA and GYPB. The molecular backgrounds of the low-frequency antigens Ny(a) and Os(a) are not known.
  
  
  METHODS
  Immunoblotting and a monoclonal antibody-specific immobilization of erythrocyte antigens (MAIEA) assay were used to analyze Os(a). PCR-amplified products of the coding exons of GYPA were studied by single-strand conformation polymorphism analysis, and exon 3 was sequenced. Synthetic peptides were used in hemagglutination-inhibition tests.
  
  
  RESULTS
  Sequencing of GYPA exon 3 of two unrelated Ny(a+) persons revealed heterozygosity for a T194A base change encoding an Asp27Glu substitution. Immunoblotting with anti-Os(a) and an MAIEA assay with MoAbs to GPA showed that Os(a) is on GPA. Sequencing exon 3 of an Os(a+) person from the only family with Os(a) revealed heterozygosity for a C273T base change encoding a Pro54Ser substitution. A synthetic peptide representing part of GPA with the Os(a) mutation (VRTVYPSEEETGE) completely inhibited anti-Os(a), whereas the control peptide (VRTVYPPEEETGE) did not inhibit anti-Os(a).
  
  
  CONCLUSIONS
  Ny(a) and Os(a) are low-frequency antigens of the MNS blood group system that represent Asp27Glu and Pro54Ser substitutions in GPA, respectively.
authors.affiliation: Bristol Institute for Transfusion Sciences and the Department of Biochemistry, University of Bristol, UK. geoff.daniels@nbs.nhs.uk
authors.forename: G L
authors.initials: GL
authors.lastname: Daniels
authors.forename: L J
authors.initials: LJ
authors.lastname: Bruce
authors.forename: W J
authors.initials: WJ
authors.lastname: Mawby
authors.forename: C A
authors.initials: CA
authors.lastname: Green
authors.forename: A
authors.initials: A
authors.lastname: Petty
authors.forename: Y
authors.initials: Y
authors.lastname: Okubo
authors.forename: L
authors.initials: L
authors.lastname: Kornstad
authors.forename: M J
authors.initials: MJ
authors.lastname: Tanner
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers; D000939:Epitopes / Q000097:blood; D004910:Erythrocyte Membrane / Q000235:genetics; D005091:Exons; D006021:Glycophorins; D006801:Humans; D015151:Immunoblotting; D007564:Japan; D008951:MNSs Blood-Group System / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D020125:Mutation, Missense; D018807:Polymorphism, Single-Stranded Conformational; D012795:Sialoglycoproteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology
chemical_list: D017931:DNA Primers; D000939:Epitopes; C409972:GYPA protein, human; C409973:GYPB protein, human; D006021:Glycophorins; D008951:MNSs Blood-Group System; D008562:Membrane Glycoproteins; D012795:Sialoglycoproteins