Morgan Gueuning from the Blood Transfusion Service in Switzerland presented at London Calling 2024 on “Targeted sequencing of the entire blood group genome by adaptive sampling.” They noted that there are over 45 blood group systems coded by fifty genes and with over 350 antigens. Precise typing and matching are essential to minimize alloimmunization. Current methods for blood group typing include qPCR, Sanger sequencing, MALDI-TOF, PCR-SSP, and digital PCR. Hybrid alleles are particularly challenging. The RH and MNS systems produce complex blood types. Gueuning and the team used the NEB Monarch HMW DNA extraction kit and the Ligation Sequencing Kit V14 (SQK-LSK114). They loaded three times (each after 24 hr) between 30-40 fmol. The P2 solo with R10.4.1 flow cells (one/sample) was used to target 64 regions (~0.26% of the human genome) covering 45 blood group systems. Fifty kb “buffer region” up and downstream of the region of interest was included. Basecalling with Dorado simplex SUP was used and reads were aligned to the reference CHM13v2.0. Variants were detected with Clair3 and Sniffles2. The team has sequenced four samples with active pores ranging from 6,500-8,200 active pores and output ranging from 37 to 80 Gbases. The N50 was about ~20 kb for all runs despite the variability in output. Blood group characterization matched MALDI-TOF assignments, though bioinformatic tools need to be improved for complex blood types and hybrid alleles. Nevertheless, the team concluded that the approach has potential.
