From DNA Methylation Microarray to Digital PCR: A Stepwise Strategy for Tissue Specific cfDNA Biomarker Development.

Area of Science:

• Biomarkers
• Molecular Diagnostics
• Genomics

Background:

• Cell-free DNA (cfDNA) is a promising biomarker for organ injury.
• Current cfDNA tissue-of-origin analysis relies on genome-wide sequencing, limiting clinical scalability.

Purpose of the Study:

• To develop a scalable workflow for creating PCR-based tissue-specific cfDNA biomarker assays.
• To establish a kidney-specific cfDNA biomarker for monitoring acute kidney injury.

Main Methods:

• Translated public DNA methylation data into PCR-compatible assays.
• Identified kidney-specific hypermethylated regions using microarray data.
• Developed and validated a digital PCR assay targeting a PAX2-associated differentially methylated region (DMR).

Main Results:

• The PAX2 methylation marker showed high specificity for kidney tissue.
• The marker was undetectable in healthy donor plasma and pre-transplant samples.
• Robust detection of the marker in post-transplant plasma indicated acute kidney injury.

Conclusions:

• A scalable method for developing PCR-based cfDNA biomarkers was established.
• The kidney-specific assay facilitates rapid, cost-effective organ injury monitoring.
• This strategy has potential applications in nephrology, oncology, and transplant medicine.