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When serology cannot fully explain a blood group result, can long-read genomics reveal what is happening at the gene level?
A 2026 proof-of-principle study in Blood Advances evaluated nanopore adaptive sampling for comprehensive blood-group genotyping, with particular attention to difficult variants in the RH and MNS systems.
The study is technically important because RH and MNS contain closely related genes and can harbor hybrid or rearranged alleles that are difficult to resolve with routine serology or standard molecular methods. The work shows how long-read sequencing may complement established immunohematology when genotype–phenotype discrepancies remain unexplained.
What did the researchers study?
The investigators analyzed five complex samples with suspected variants that had not been resolved by standard molecular or serologic testing. Four samples came from blood donors and one from a patient with sickle cell disease. Each case had either a genotype–phenotype discrepancy, unusual antigen expression, or unexplained antibody findings.
Using Oxford Nanopore adaptive sampling, the team selectively enriched blood-group loci during sequencing while preserving long DNA reads. The targeted design covered genes associated with erythrocyte, platelet, and neutrophil antigens, while the main difficult cases involved RHD/RHCE and the glycophorin genes underlying the MNS system.
What did the study find?
On-target mean sequencing coverage ranged from approximately 18.9× to 53.4× across the five samples. The researchers successfully assembled the suspected hybrid alleles and generated full haplotypes for complex variants that had been difficult to characterize using conventional approaches.
The study also identified numerous previously unreported coding variants or variant combinations across the broader blood-group genome. Importantly, the authors emphasized that novel sequence findings still require appropriate confirmation and biological interpretation before they can be translated into antigen predictions or clinical decisions.
Plain-language summary
Serology tells us what antigens appear to be present or absent on the red blood cell. Genotyping asks which genetic variants are likely to produce those antigens.
Most of the time, routine serology and standard genotyping provide enough information. But some RH and MNS variants are structurally complex. A piece of one gene may be joined to another, or a hybrid allele may contain a sequence pattern that short-read or targeted methods cannot fully reconstruct.
Long-read sequencing can span much larger portions of DNA. In this study, that allowed the researchers to reconstruct difficult alleles more completely and connect genetic structure with the laboratory findings.
Gene → antigen → laboratory interpretation → transfusion significance.
Why this matters for transfusion medicine
Accurate blood-group characterization can be particularly important when patients require repeated transfusions, develop antibodies, or have uncommon antigen profiles. Better molecular resolution could eventually help laboratories distinguish complex variants and improve the precision of donor–recipient matching.
However, this study did not test whether the sequencing strategy reduces alloimmunization, prevents transfusion reactions, improves patient outcomes, or should replace routine serology.
Methodological quality
Overall assessment: MODERATE for technical feasibility; LOW for clinical-effectiveness claims.
The study provides strong proof-of-principle evidence that adaptive nanopore sequencing can resolve selected complex RH and MNS alleles. The investigators used real difficult samples, compared findings with prior serologic and molecular workups, applied both reference-based and de novo assembly strategies, and made the resulting haplotype sequences available in GenBank.
But the sample size was only five, the cases were intentionally selected because they were difficult, and there was no prospective clinical comparison showing improved transfusion outcomes. The work therefore supports feasibility and analytical potential—not routine clinical replacement of validated serology.
Strengths
- Direct focus on clinically relevant genotype–phenotype discrepancies.
- Long-read sequencing enabled reconstruction of complex hybrid alleles and full haplotypes.
- Use of both reference-based analysis and de novo assembly improved analytical robustness.
- The workflow targeted blood-group loci rather than performing unrestricted whole-genome sequencing.
- Haplotype sequence data were deposited in GenBank, supporting reproducibility and future reference development.
Limitations
- Only five complex samples were studied.
- The study was designed as a proof-of-principle, not as a diagnostic-accuracy or clinical-outcomes trial.
- Per-sample cost remains relatively high because enrichment efficiency is still limited.
- Blood-group-specific bioinformatics and allele interpretation tools still require further development.
- Novel or low-coverage variants require orthogonal confirmation before diagnostic use.
Funding and conflicts of interest
The authors reported no competing financial interests. The work was financially supported by the Blood Transfusion Service Zurich, Swiss Red Cross.
🔎 Soleil Insight
The most important message is not that genomics is replacing serology.
It is that the two methods answer different but complementary questions.
Serology shows what the red blood cell is expressing. Genomics can help explain why.
For routine transfusion testing, validated serologic methods remain essential. But when phenotype and genotype disagree, when antibodies are unexplained, or when RH and MNS structures are unusually complex, long-read sequencing may provide an additional layer of resolution.
This is the direction in which precision transfusion medicine is evolving: not abandoning established laboratory methods, but integrating them with increasingly powerful molecular tools where the evidence supports their use.
Bottom line
Nanopore adaptive sampling successfully resolved complex blood-group alleles in a small proof-of-principle series and demonstrated the value of full-gene, long-read analysis for RH and MNS variants.
The findings are promising for molecular blood-group diagnostics and future donor–recipient matching, but broader validation, lower cost, standardized bioinformatics, and prospective clinical evidence are still needed before routine implementation.
Original publication
Gueuning M, Thun GA, Koller S, et al. Proof-of-principle: nanopore adaptive sampling enables full blood group genome analysis and resolution of hybrid alleles. Blood Advances. 2026;10(3):864–875.
DOI: 10.1182/bloodadvances.2025017463
This article is for scientific and educational communication and does not replace validated laboratory procedures, institutional transfusion policies, or clinical judgment.
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