Body: Accurate HLA typing is critical for safe and efficient deceased donor kidney allocation. Although low-resolution typing approach allows timely allocation, nucleic acid variations may not be detected, potentially affecting recipient compatibility and allocation outcome. A deceased donor was HLA typed using sequence-specific oligonucleotide (SSO) assays, revealing B39 and B60 (B*40:01). High-resolution typing using Nanopore sequencing identified a novel 5-bp insertion in exon 2 of the B*40:01 allele, confirmed by next-generation sequencing (NGS) and sequencing-based typing (SBT). This insertion introduced a frameshift mutation and a predicted premature stop codon in the B60 peptide sequence. Serological typing confirmed the absence of B60 antigen expression, indicating the presence of a B60 null allele. Antibody filtering and waitlist mapping were performed according to the two different typing results and were found to yield different candidate allocations. Differences were attributed to the changes in allocation scores, underscoring how high-resolution typing impacts candidate ranking and allocation.
Conclusion: This case highlights a significant limitation of low-resolution HLA typing in deceased donor kidney allocation. While low-resolution results are sufficient for fast processing, novel or null alleles will be missed, altering candidate matching in organ allocation. High-resolution HLA typing improves the accuracy of HLA typing by including allelic variations and enhancing waitlist mapping fidelity in deceased organ allocation. Strategies to adapt rapid high-resolution typing into urgent workflow are needed to optimize matching and improve transplant outcomes.
