P106 LinkSēq for ABO, a molecular based typing solution for the ABO blood group

Abstract

Aim ABO-incompatible (ABOi) organs have been successfully transplanted from A2 donors into B recipients, especially when the recipient’s anti-A titers are reduced. Laboratories typically use serological methods to perform ABO typing. However, serology has significant limitations including (i) recently transfused patients may exhibit mixed field agglutination and (ii) both forward and reverse typing must be performed, but may yield discordant results. These limitations are most problematic with phenotypes involving weakly expressed antigens and ABO subgroups (i.e. A2). However, current ABO subgrouping methods using anti-A1 lectin have limitations: they only indirectly determine A2, and typically include a gray zone reactivity range for which subgroups cannot be reliably called. A combination of genotyping solutions (SSP, sequencing, etc) can be used for ABO subgrouping, but these methods are time- and labor-consuming, and require interpretation by subject matter experts. Methods The Thermo Fisher Scientific solution is based on its LinkSēq real-time PCR technology, which was developed over 10 years ago for genotyping the complex Human Leukocyte Antigen (HLA) system. LinkSēq ABO analyzes 19 reactions that identify multiple relevant SNPs located within the ABO gene. We evaluated this solution by analyzing 40 archived DNA samples, including blood blank samples for which serotyping failed or produced discordant results, and samples from deceased solid organ donors for comparison with A1 lectin testing. Results Genotyping results generated by LinkSēq were 100% concordant with typing obtained by traditional methodologies. In two cases, serology couldn’t provide conclusive results and typing had to be reflexed to lectin tests or SBT. LinkSēq overcomes the major challenges of molecular typing by providing a robust, automated approach that increases laboratory productivity and reduces turn-around time. With less than 10 min of hands-on set-up, no further operator intervention with reagents, and SureTyper software fully automating all analysis, LinkSēq delivers genotyping and predicted phenotyping results in approximately 90 min. Conclusions We conclude that LinkSēq can provide a simple, effective and robust method for ABO typing including accurate A2 subgrouping.