Applicability of Whole Genome Sequencing for Human Blood Group Genotyping and Genetic Definition of New Alleles as Exemplified on References and the Two MNSs-variants: U- and Stones(a)+

All 34 human blood group systems have at least two antithetical antigens and are of potential relevance during pregnancy and transfusion. Fortunately for every day routine practice, immunizations to foreign antigens are rare. Still, incompatibilities may occur in all blood group systems and will then require typing for the respective blood group antigens.

Blood genotyping evolved as the method of choice, in cases when typing reagents are commercially unavailable, or blood is inaccessible (foetus). In databases, most entries of blood group genes lack representative polymorphism (e.g. number of alleles). Moreover, many blood group antigens are insufficiently described in their intronic and inter-genetic sequences. This is true for results of unequal crossing-overs, gene-conversions and large insertions/deletions between highly homologous genes, especially within the blood group systems of Rhesus, e.g. RhD/RhCE and MN/Ss, respectively. Only Whole Genome Sequencing (WGS) allows for resolution of both problems: it delivers the whole blood group genome of an individual, and simultaneously recognizes new blood group alleles, or haplotypes. This request for ethical approval wants to test this assumption.

The antigenic determinants U- and Stones(a)+ of the blood group system MNSs still lack full genetic description and will serve as challenging examples for the description of new alleles (haplotypes) caused by large ins/del mutations of the two highly homologous genes GYPA and B. Genomic DNA of 2 U- samples were both provided as blinded reference material from New York and Vienna blood centres, respectively. Both donors are lost for follow up, and although there is no documented evidence for refusal of the respective donors to use their material in research projects, samples still lack informed consent. Additional reference samples (n max=4), and samples with suspected Stones(a)+ (n max=4) will be recruited from Zurich blood donors with informed consent, only.