Dr. Maja P. Mattle-Greminger (Schlieren/ CH), Dr. Stefan Meyer (Schlieren/ CH), Prof. Dr. Andreas Greinacher (Greifswald/ DE), Jeremy Gollub (Santa Clara, CA/ US), Ellen van der Schoot (Amsterdam/ NL), Andrea Harmer (London/ GB), Connie M. Westhoff (New York, NY/ US), Willem H. Ouwehand (London/ GB; Cambridge/ GB), William J. Lane (Boston, MA/ US), Nicholas Gleadall (Cambridge/ GB), Dr. Barbera Veldhuisen (Amsterdam/ NL), (Group) The Blood transfusion Genomics Consortium (Cambridge/ GB)
Background
Extended blood group matching substantially reduces sensitization to non-self antigens as side effect of transfusion. For broad application, affordable high-throughput typing of relevant antigens is required. Following an earlier proof-of-concept study, our consortium presents here the development of a tailored universal blood donor genotyping array, including the results of an international Pre-Clinical accreditation Study (PCS) comprising an ethnically highly diverse panel of samples.
Methods
The custom-designed Axiom array contains 50,000 probes tagging 20,000 variants relevant for blood services. It has a 384-sample format and runs on GeneTitan instrument, which can generate data for 3,000 samples/week. The array allows simultaneous typing of clinically relevant human erythroid (HEA), platelet (HPA), and leukocyte (HLA) antigens. For the PCS, DNA samples and clinical antigen typing data from 13,908 donors provided by seven blood services were analysed. Samples representing diverse ethnic groups (74% European, 11% African, 15% others) were genotyped at three blood services in the Netherlands, USA, and UK. Array-inferred antigen types were analysed for concordance with provided clinical antigen types for the first 6,953 samples.
Results
Reproducibility between sample results from the testing laboratories was outstanding for the 20k variants. The overall concordance for HEA, HPA, and HLA antigens with previous testing was very high. Of ~100,000 comparisons between blood service determined HEA types and array determined types, the concordance was 99.8%. Over 80% of the discordances can be resolved by simple algorithmic modifications and over half of the remaining ones were caused by incorrect serology. The results of the PCS proofed a robust validation of also non-European genotypes configurations. The 778 samples of African ancestry showed a HEA concordance rate >99.7%. Also HLA class I and II concordance level, which could be assessed for 1319 DNA samples, was excellent.
Conclusion
An affordable and comprehensive DNA-based test for automated high-throughput typing of donors and patients is reported here. The universal blood typing array is tailored for the needs of transfusion services and validated in an international, diverse cohort. Among others, the array represents a promising new tool to facilitate a broader application practise of extended blood matching to reduce sensitization rates and to identify rare donors.
Offenlegung Interessenkonflikt:
The Blood transfusion Genomics Consortium was financially supported by Thermo Fisher Scientific (Santa Clara, USA) for the development of the Axiom array.