Premium
New and unusual O alleles at the ABO locus are implicated in unexpected blood group phenotypes
Author(s) -
HosseiniMaaf Bahram,
Irshaid Nidal M.,
Hellberg Åsa,
Wagner Thomas,
Levene Cyril,
Hustinx Hein,
Steffensen Rudi,
Chester M. Alan,
Olsson Martin L.
Publication year - 2005
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/j.1537-2995.2005.04195.x
Subject(s) - abo blood group system , allele , locus (genetics) , phenotype , genetics , biology , gene
BACKGROUND: In the ABO blood group system mutations in the A gene may lead to weak A subgroups owing to a dysfunctional 3‐α‐ N ‐acetylgalactosaminyltransferase. STUDY DESIGN AND METHODS: Blood and DNA were investigated to correlate weak A phenotypes with genotype, and an overrepresentation of the infrequent O 2 allele was observed. Consequently, 57 available O 2 alleles were examined in detail. RESULTS: Two new O 2 alleles were identified having mutations resulting in Gly229Asp with or without Arg217Cys. A recently described O 2 variant (488C>T; Thr163Met) was also found. Surprisingly, both the original and the variant O 2 alleles were associated with either O or A weak phenotypes. Three novel O alleles surfaced in six other samples with suspected A subgroups. These were A 1 ‐like alleles having nonsense mutations causing premature truncation at codons 56, 107, or 181. A second example of the rare O 3 allele was also identified. A newly described O 1 allele having 768C>A was found to be the third most frequent O allele among Swedish donors. Of the five novel O alleles, three were incorrectly interpreted as A 1 following routine ABO genotyping. CONCLUSION: Apparent O alleles lacking 261delG may cause weak A expression on red blood cells and/or inhibit anti‐A production. A hypothesis that exchange of genetic material between principally dissimilar O alleles during mitosis (“autologous chimerism”) restores glycosyltransferase activity in some cells would explain this interesting phenomenon.