️ Episode 147: Comprehensive Annotation of Complete ABO Alleles and Resolution of ABO Variants

In this episode of PaperCast Base by Base, we explore a groundbreaking study that introduces an improved long-read sequencing method to fully resolve ABO haplotypes, spanning from the 5′ to the 3′ untranslated regions. This work addresses a major gap in blood group genomics by delivering the most comprehensive annotation of complete ABO alleles to date.

Study Highlights:
Researchers analyzed specimens from 79 blood donors and 47 ABO variants using an optimized ultra-long-range PCR method combined with PacBio SMRT sequencing. They successfully amplified and sequenced the full 26.1 kb ABO gene without splicing, achieving complete coverage including the regulatory 5′ and 3′ UTRs. The study provided detailed haplotype sequences of predominant alleles in a Chinese population, revealing structural variations, recombination events, and previously unknown subtypes. Importantly, this method also resolved complex variants, including large deletions, chimeras, and intronic regulatory motifs, offering new insights into ABO allele diversity and molecular mechanisms.

Conclusion:
This comprehensive full-length ABO haplotype sequencing approach advances transfusion medicine by improving variant resolution, refining allele classification, and enabling more accurate genomic analysis for clinical and evolutionary applications.

Reference:
Ying Y, Zhang J, Hong X, Yuan W, Ma K, Huang X, Xu X, Zhu F. Comprehensive Annotation of Complete ABO Alleles and Resolution of ABO Variants by an Improved Full-Length ABO Haplotype Sequencing. *Clinical Chemistry*. 2025;71(4):510–519. https://doi.org/10.1093/clinchem/hvaf015

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

Support:
If you'd like to support Base by Base, you can make a one-time or monthly donation here: https://basebybase.castos.com/

Chapters

• (00:00:00 ) - Base by Base: The mystery of blood types
• (00:01:27 ) - Full-length ABO haplotype sequencing
• (00:06:05 ) - Anatomy 5, Chinese genetic variation
• (00:06:54 ) - The structural variations of the ABO genome
• (00:09:38 ) - ULRPCR: The Bigger Alga