Characterization of a novel O1 variant allele at the ABO blood group locus

We describe the identification and molecular characterization of a novel variant O-1 allele of the ABO blood group locus. The allele was found in a young child and by analyzing the maternal DNA we were able to show that a meiotic recombination event between the maternal O1v-3 and B1-1 alleles recreated a O-1/B hybrid allele. Further characterization of intron 6 sequences delineated the putative recombination breakpoint between nucleotide position 42 and 163 of the intron. We propose that the novel O-1variant allele should be named O-1v.7 and is a combination of exon 6 from it O-1v.3 allele and exon 7 from a B-M allele.