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"Same difference": comprehensive evaluation of four DNA methylation measurement platforms.
Thadeous J Kacmarczyk1, Mame P Fall2, Xihui Zhang2
1Division of Hematology/Oncology, Department of Medicine, Epigenomics Core Facility, Weill Cornell Medicine, New York, NY, USA. thk2008@med.cornell.edu.
Epigenetics & Chromatin
|May 27, 2018
Summary
Comparing DNA methylation analysis methods, targeted capture platforms offer high coverage of designed regions with fewer off-target loci than restriction enzyme-based methods. The choice depends on sample number, DNA quality, and research focus.
Area of Science:
- Epigenetics and Genomics
- Molecular Biology Techniques
Background:
- DNA methylation in CpG context is crucial for epigenetic gene regulation in eukaryotes.
- Altered methylation patterns are linked to diseases, differentiation, and imprinting.
- Cost-effective methods are needed to enrich for high CpG content regions for sequencing.
Purpose of the Study:
- To evaluate and compare four DNA methylation analysis methods: three in-solution custom-capture hybridization platforms and one restriction enzyme-based reduced representation bisulfite sequencing protocol.
- To assess similarities and differences in CpG locus coverage, annotation, and performance.
- To guide the selection of appropriate methods based on experimental needs.
Main Methods:
- Comparison of targeted capture (Agilent, NimbleGen, Illumina) and restriction enzyme-based reduced representation bisulfite sequencing.
- Evaluation of CpG locus coverage, on-target rates, and annotation proportions.
- Assessment of DNA quality requirements, starting material needs, and cost-effectiveness.
Main Results:
- Targeted capture methods achieved >95% coverage of designed regions; restriction enzyme methods covered >70% of expected fragments.
- While shared CpG loci were low (~24%), methylation levels were concordant across all platforms.
- Targeted capture methods showed similar annotation profiles, with restriction enzyme methods covering fewer promoters and CpG shores.
Conclusions:
- Commercially available capture methods provide high on-target rates and similar annotation proportions, with fewer off-target loci compared to restriction-based methods.
- Restriction-based enrichment is sensitive to DNA quality and can yield more off-target and unannotated loci.
- Method selection depends on sample size, DNA availability, and specific biological interests, as all platforms yield comparable data.