Involvement of Gly96 in the formation of the Rh26 epitope.
BACKGROUND
The Rh system, a complex blood group system, comprises at least 45 antigens. Red cells expressing c usually express Rh26. Rare cells that are c+ Rh:-26 give variable reactions with anti-c and may have weak expression of f (ce).


METHODS
Serologic and molecular studies were performed with red cells from persons with the c+ Rh:-26 phenotype occurring in two unrelated Dutch families. Red cells of 11 members of these two families were typed for Rh26, for c (with monoclonal and polyclonal reagents), and for f (ce). The cDNA of three donors was sequenced, while restricted DNA analysis was carried out on material from available members of the two families.


RESULTS
Serologic tests showed that the rare c+ Rh:-26 phenotype was associated with a weak expression of c and a normal expression of f. The cDNA analysis of three members of one family revealed a single-point mutation (G286A) in exon 2 of the ce allele. Allele-specific primer amplification, polymerase chain reaction followed by allele-specific restriction analysis, and single-strand conformation polymorphism showed the same polymorphism in all other members of both families, whereas it was absent in 80 control donors.


CONCLUSIONS
The c+ Rh:-26 phenotype, identified in two families, is associated with a single-point mutation at nucleotide 286 (G286A) in the ce allele, which predicts a Gly96Ser amino acid substitution. This substitution also affects c, because all anti-c reagents reacted more weakly. Other polymorphic sites apparently are involved in the formation of the Rh26 epitope as well, because Rh26 is expressed only on the c polypeptide, whereas Gly96 is expressed on all polypeptides.
Faas
B H
BH
Central Laboratory of The Netherlands Red Cross Blood Transfusion Service, Amsterdam, The Netherlands.
Ligthart
P C
PC
Lomas-Francis
C
C
Overbeeke
M A
MA
von dem Borne
A E
AE
van der Schoot
C E
CE
D000483:Alleles; D019943:Amino Acid Substitution / Q000235:genetics; D015139:Blotting, Southern; D004247:DNA / Q000032:analysis / Q000235:genetics; D017931:DNA Primers; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D000939:Epitopes / Q000097:blood / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005998:Glycine / Q000235:genetics*; D006801:Humans; D007962:Leukocytes / Q000737:chemistry; D009426:Netherlands; D010375:Pedigree; D017354:Point Mutation / Q000235:genetics; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D018807:Polymorphism, Single-Stranded Conformational; D015183:Restriction Mapping; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D012694:Serine / Q000235:genetics; D012698:Serologic Tests
D017931:DNA Primers; D018076:DNA, Complementary; D000939:Epitopes; D012204:Rh-Hr Blood-Group System; D012694:Serine; D004247:DNA; D005998:Glycine