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Updated: May 31, 2026
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Ultra-long Read Sequencing for Whole Genomic DNA Analysis
Published on: March 15, 2019
Whole-genome variant detection in long-read sequencing data from ultralow input patient samples
Katherine Wang1,2, Cera J Aex1, Hayan Lee2
1Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA.
Genome Research
|May 28, 2026
Summary
Ultra-low input HiFi (ULI-HiFi) sequencing offers superior detection of genetic variants, including tandem repeats and small variants, compared to droplet multiple displacement amplification (dMDA). This advancement aids in understanding complex genomic regions and diseases like colorectal cancer.
Area of Science:
- Genomics
- Molecular Biology
- Cancer Research
Background:
- Long-read sequencing offers a more comprehensive genomic view than short-read sequencing, excelling in detecting structural variants and variants in challenging genomic regions.
- A significant limitation of long-read sequencing is its high input DNA requirement, typically several micrograms per sample.
- Amplification methods are crucial for reducing DNA input, but their performance in long-read sequencing needs thorough evaluation.
Purpose of the Study:
- To evaluate and compare two amplification-based long-read whole-genome sequencing methods: ultra-low input HiFi (ULI-HiFi) and droplet multiple displacement amplification (dMDA).
- To assess the accuracy and efficiency of ULI-HiFi and dMDA in detecting various genetic variants, including single nucleotide variants and tandem repeats.
- To explore the utility of ULI-HiFi in analyzing medically relevant genes and patient samples, particularly in the context of hereditary colorectal cancer.
Main Methods:
- Benchmarking ULI-HiFi and dMDA against the Genome in a Bottle reference set (NA24385) for variant detection accuracy.
- Analysis of over 1.6 million tandem repeats (TRs) to evaluate ULI-HiFi's performance in repetitive genomic regions.
- Application of ULI-HiFi to sequence and analyze normal, polyp, and adenocarcinoma samples from a familial adenomatous polyposis (FAP) patient.
Main Results:
- ULI-HiFi demonstrated significantly higher precision and recall for single nucleotide variants (SNVs) compared to dMDA (F1 scores of 99.82% vs. 89.46%).
- ULI-HiFi achieved high concordance (90.4% perfect, 98.9% accurate with single motif differences) across a large catalog of tandem repeats.
- ULI-HiFi successfully identified an expanding tandem repeat in the 5' UTR of the tumor suppressor gene *LIMD1*, correlating with reduced gene expression in colorectal cancer progression.
Conclusions:
- ULI-HiFi sequencing significantly improves the characterization of genetic variants, especially in previously difficult-to-map genomic regions ('dark regions').
- The method enables better detection of medically important variants, including tandem repeat expansions linked to hereditary cancer syndromes like FAP.
- ULI-HiFi offers a powerful tool for advancing our understanding of human disease by providing deeper insights into complex genomic variations.
