Search

The advent of third‐generation sequencing (TGS) represents a significant shift in the field of genetic sequencing, enabling single‐molecule sequencing to overcome limitations of short‐read NGS platforms. Several studies have assessed the utilisation of TGS in HLA genotyping, though many of these studies have described the high error rate as an obstacle to achieving a robust and highly accurate HLA typing assay. In 2021, Oxford Nanopore Technologies (ONT) released the high‐accuracy sequencing Kit 14 and the MinION flow cell model R10.4.1, which were reported to achieve sequencing accuracies up to 99%. The aim of this study was to validate this novel high‐accuracy sequencing kit for HLA genotyping coupled with a full‐gene HLA PCR assay. Comparison with historical data obtained using legacy flow cell models such as R9.4, R10.3 and R10.4 was also done to assess progressive improvement in sequencing performance with each sequential release. The workflow was validated based on data throughput, sequence quality and accuracy, and HLA genotyping resolution. An initial validation was performed using an internal reference panel of 42 samples representing common HLA allele groups, followed by an analysis of data obtained from 111 sequencing batch runs since the implementation, to assess assay performance and define quality control metrics to assess inter‐run variability and monitor quality. Furthermore, challenges arising from MinION flow cell stability and use, and assessment of barcode contamination are discussed. The findings of this study highlight advantages of ONT sequencing kit 14/R10.4.1 for HLA genotyping and the implementation considerations for the routine diagnostic HLA laboratory. [ABSTRACT FROM AUTHOR]

The primary goal of the HLA‐DPA1 ~ promoter ~ HLA‐DPB1 haplotype component of the 18th IHIWS was to characterise the extended haplotypes within the HLA‐DP region and survey the extent of genetic diversity in this region across human populations. In this report, we analysed single‐nucleotide polymorphisms (SNPs) in 255 subjects from 6 different cohorts. The results from the HLA‐DP haplotype component have validated findings from the initial pilot study. SNPs in this region were inherited in strong linkage, particularly HLA‐DPA1, SNP‐linked promoter haplotypes and motifs in exon 2 of HLA‐DPB1. We reported 17 SNP‐linked haplotypes in the promoter region. Together with HLA‐DPA1 and HLA‐DPB1 alleles, they formed 74 distinct extended HLA‐DP haplotypes in 438 sequences. We also observed the presence of region‐specific alleles and promoter haplotypes. Our approach involved phasing extended SNPs including promoter SNPs, HLA‐DPA1 and HLA‐DPB1 alleles, in a 22 kb region, GRCh38/hg38 (chr6:33,064,111‐33,086,679), followed by clustering of these SNPs as one extended haplotype. This hierarchical clustering revealed four major clades, suggesting that haplotypes within each clade may have diverged from a common ancestral haplotype and undergone similar evolutionary processes. The correlation between HLA‐DPA1 and the promoter region raises questions about the role of HLA‐DPA1 antigen in the heterodimer. This finding requires validation on a larger sample size specifically designed for anthropological analysis. Nevertheless, the results from this study highlight the clinical potential of selecting better‐matched donors for patients awaiting haematopoietic stem cell transplants from genetically overlapping groups that share common ancestral haplotypes. [ABSTRACT FROM AUTHOR]

The advent of third-generation sequencing (TGS) represents a significant shift in the field of genetic sequencing, enabling single-molecule sequencing to overcome limitations of short-read NGS platforms. Several studies have assessed the utilisation of TGS in HLA genotyping, though many of these studies have described the high error rate as an obstacle to achieving a robust and highly accurate HLA typing assay. In 2021, Oxford Nanopore Technologies (ONT) released the high-accuracy sequencing Kit 14 and the MinION flow cell model R10.4.1, which were reported to achieve sequencing accuracies up to 99%. The aim of this study was to validate this novel high-accuracy sequencing kit for HLA genotyping coupled with a full-gene HLA PCR assay. Comparison with historical data obtained using legacy flow cell models such as R9.4, R10.3 and R10.4 was also done to assess progressive improvement in sequencing performance with each sequential release. The workflow was validated based on data throughput, sequence quality and accuracy, and HLA genotyping resolution. An initial validation was performed using an internal reference panel of 42 samples representing common HLA allele groups, followed by an analysis of data obtained from 111 sequencing batch runs since the implementation, to assess assay performance and define quality control metrics to assess inter-run variability and monitor quality. Furthermore, challenges arising from MinION flow cell stability and use, and assessment of barcode contamination are discussed. The findings of this study highlight advantages of ONT sequencing kit 14/R10.4.1 for HLA genotyping and the implementation considerations for the routine diagnostic HLA laboratory., (© 2024 The Author(s). HLA: Immune Response Genetics published by John Wiley & Sons Ltd.)