Novel Method Enables Gentle and Accurate DNA Methylation Sequencing

A research team at The University of Chicago has developed a new DNA methylation sequencing method that achieves high accuracy while preserving fragile DNA. Published in Nature Communications, the study describes Ultra‑Mild Bisulfite Sequencing (UMBS‑seq), a refined approach that reengineers traditional bisulfite chemistry to minimize DNA damage and improve reliability in cancer biomarker detection.

DNA methylation, the addition of a chemical tag known as 5‑methylcytosine (5mC) to DNA, is a key epigenetic signal that regulates gene expression. These methyl marks help determine whether genes are turned on or off, influencing how identical genetic material is used across different cell types. Abnormal methylation patterns are characteristic of many cancers, where they can deactivate tumor‑suppressor genes or activate oncogenes. Detecting these changes with high sensitivity is vital for early diagnosis, treatment monitoring, and selecting targeted therapies. 

For decades, bisulfite sequencing has served as the gold standard for reading methylation patterns by converting unmethylated cytosines into a different base detectable by sequencing. However, the process uses harsh chemical conditions that often fragment DNA, leading to poor yield and biased results, particularly when studying short, fragile DNA fragments such as those circulating in blood or obtained from fixed tissue. Newer enzyme‑based sequencing methods offer milder treatment but introduce false positives and require complex workflows that limit consistency.

To solve these problems, the University of Chicago team designed UMBS‑seq, which modifies the bisulfite reaction itself to achieve nearly complete cytosine conversion under ultra‑mild conditions. This approach maintains the strengths of bisulfite chemistry while drastically reducing DNA degradation. The method demonstrated higher library yields, greater genomic coverage, and more accurate methylation calls than both conventional bisulfite and enzyme‑based techniques. Its simplified workflow also shortens processing time and improves reproducibility.

When applied to human cell‑free DNA samples—the fragile molecules often used in non‑invasive liquid biopsies—UMBS‑seq preserved DNA integrity and provided more complete methylation coverage across cancer‑related genomic regions than major commercial kits. These results suggest that UMBS‑seq could serve as a new standard for methylation sequencing, balancing chemical efficiency with sample preservation.

According to Ruitu Lyu, a co‑author of the study, “It’s a practical and scalable solution that could accelerate the clinical use of methylation biomarkers for early detection and personalized therapy.”