The low-frequency MNS blood group antigens Ny(a) (MNS18) and Os(a) (MNS38) are associated with GPA amino acid substitutions.
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.
Daniels
G L
GL
Bristol Institute for Transfusion Sciences and the Department of Biochemistry, University of Bristol, UK. geoff.daniels@nbs.nhs.uk
Bruce
L J
LJ
Mawby
W J
WJ
Green
C A
CA
Petty
A
A
Okubo
Y
Y
Kornstad
L
L
Tanner
M J
MJ
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
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