Targeted Methylation Capture Sequencing Platform

Targeted Methylation Capture Sequencing Platform

High-Depth Targeted Methylation Profiling of Functional Genomic Regions

1. Background

Targeted Methylation Capture Sequencing combines the broad coverage advantages of RRBS with the targeting precision of amplicon sequencing. By designing hybridization probes against specific genomic regions, it achieves high-depth methylation detection of the regions of interest. This technology is particularly suited for medium-scale (0.5 M–5 M) functional region studies, offering an excellent balance between cost and coverage.

As epigenomics research has advanced, it has become clear that many disease-associated methylation changes are concentrated in specific genomic regions, such as promoters, enhancers, and CpG island shores. Targeted capture technology enables researchers to focus on these functionally important regions, obtaining high-quality methylation data at reduced cost while avoiding the enormous data volumes and analytical burden of whole-genome sequencing.

This technology has been widely applied in tumor epigenetics, complex disease research, and drug target discovery. Through customized panel design, it enables deep methylation analysis of gene sets relevant to specific diseases or biological processes, providing powerful support for precision medicine and translational research.

2. Detection Principle

The core principle of targeted methylation capture technology is to use biotin-labeled probes for solution-phase hybridization with target DNA regions, followed by streptavidin magnetic bead-based specific enrichment of DNA fragments containing the target sequences. The entire workflow is performed after bisulfite conversion, ensuring that both target region capture and methylation information retention are achieved.

The workflow includes: first, fragmentation of high-quality genomic DNA (200–300 bp), followed by end repair and adapter ligation, and then bisulfite conversion; a set of comprehensive probes (typically 120 bp oligonucleotides) is then designed for the target regions — these probes are designed against bisulfite-converted sequences and can simultaneously recognize both methylated and unmethylated DNA; the converted library undergoes solution-phase hybridization with the probes (typically 16–24 hours) to allow thorough probe-target binding; streptavidin magnetic beads are used to capture the biotin-labeled probe-DNA complexes, and non-specific binding is removed through stringent washing steps; finally, the enriched DNA is PCR-amplified and sequenced.

Bioinformatic analysis aligns sequencing reads to the target regions and calculates the methylation level at each CpG site. This method achieves an average coverage depth of 100–500X, sufficient for accurate methylation quantification and differential analysis. Compared to PCR amplification, probe capture exhibits superior uniformity and lower GC bias.

Figure 1. Schematic diagram of the targeted methylation capture sequencing workflow

3. Technology Innovation and Advantages

3.1 Targeted Methylation Capture Technology Advantages

Targeted methylation capture offers distinct advantages over other methylation sequencing technologies, including maximum flexibility (fully customizable), superior uniformity (low GC bias, high capture uniformity), deep coverage (extremely high sequencing depth achievable in target regions), and precise focus (eliminates sequencing waste by concentrating resources on regions of interest). It is especially suitable for:

(1) Candidate genes or regions where the research focus has been clearly established

(2) Studies requiring extremely high depth coverage for fine-scale quantification

(3) Multi-gene panel applications in clinical diagnostics

(4) The transition phase from discovery (WGBS/RRBS) to validation

(5) Long-term projects requiring periodic updates to the target region panel

Figure 2. Comprehensive performance comparison of mainstream methylation sequencing technologies

3.2 Intelligent Probe Design Strategy

An advanced probe design system has been developed to ensure efficient capture:

(1) Strand-specific design: Probes are designed separately for both the positive and negative strands following bisulfite conversion to ensure capture efficiency.

(2) High-density coverage: Overlapping probe tiling design ensures gap-free coverage of target regions.

(3) Repeat sequence handling: Optimized probe design for repetitive sequence regions improves coverage of these difficult-to-capture areas.

(4) Panel flexibility: Supports both pre-designed panels (e.g., tumor-related genes, imprinted genes) and fully customized panel design.

3.3 Optimized Hybridization Capture System

A highly efficient hybridization capture workflow has been established:

(1) Optimized hybridization conditions: Precise control of temperature, time, and reaction components to maximize capture specificity and efficiency.

(2) Stringent washing strategy: Multi-step gradient washing to effectively remove non-specific binding and reduce background noise.

(3) Multi-sample parallelization: Supports simultaneous hybridization capture of multiple samples for improved throughput.

(4) Quality control system: Each batch includes positive and negative controls to verify that capture efficiency meets standards.

3.4 Professional Bioinformatics Analysis

Comprehensive data analysis services are provided:

(1) Capture efficiency assessment: On-target rate analysis and coverage uniformity evaluation.

(2) Methylation quantification: Calculation of methylation levels at individual CpG sites and across defined regions.

(3)Differential methylation analysis: DMR identification, statistical testing, and effect size assessment.

(4) Functional annotation: Gene function, pathway enrichment, and disease association analysis.

(5)Multi-dimensional visualization: Circos plots, heatmaps, genome browser views, and more.

4. Application Scenarios and Service Advantages

4.1 Application Scenarios

Targeted methylation capture sequencing technology offers unique advantages across multiple research fields:

(1) Pathway-specific methylation research: Key signaling pathway-related genes such as the Wnt pathway, p53 pathway, and cell cycle pathway.

(2) Disease-associated gene panels: Cancer-related genes, neurodegenerative disease genes, metabolic disease genes, etc.

(3) Regulatory element methylation analysis: Promoters, enhancers, CpG island shores, transcription factor binding sites, etc.

(4) Imprinted gene research: Detection of methylation status at imprinting control regions (ICRs) and imprinted gene clusters.

(5) Candidate region in-depth analysis: Fine-scale methylation profiling of candidate regions identified by GWAS or EWAS.

(6) Drug target methylation: Assessment of methylation changes in drug action-related genes.

(7) Evolutionary epigenetics: Comparative methylation studies across evolutionarily conserved regions in multiple species.

(8) iPSC cell therapy and epigenetic editing: Methylation monitoring during iPSC reprogramming and differentiation, assessment of epigenetic effects of gene editing, quality control of iPSC therapy products, and tracking of epigenetic remodeling during iPSC differentiation.

4.2 Service Advantages

(1) Balanced cost-effectiveness: Sequencing cost reduced by 70–80% compared to WGBS, with 100–1,000-fold broader coverage compared to amplicon sequencing.

(2) Flexible panel design: Supports panels of varying scales from 0.5 M to 5 M bp, fully customizable to research needs.

(3) High data quality: Probe capture technology exhibits low GC bias and superior coverage uniformity over PCR-based methods.

(4) Pre-designed panels available: Standard panels for oncology, neurology, metabolism, and other disease areas are offered.

(5) Mature technology: Built on a well-established commercial capture platform.

(6) Rapid delivery: Standard service turnaround 5–7 weeks; expedited service available in 4 weeks.

(7) Comprehensive analysis: Full suite of bioinformatics services from basic to advanced analysis.

5. Targeted Methylation Capture Sequencing Analysis Report Examples

We provide comprehensive and professional targeted capture methylation analysis reports containing the following core components:

(1) Data Quality Assessment: Key metrics including sequencing data volume, Q30 ratio, GC content, duplication rate, and mapping rate.

(2) Capture Efficiency Statistics: On-target rate, enrichment fold, and target region coverage statistics.

(3) Coverage Depth Distribution: Cumulative coverage curves, depth distribution histograms, and uniformity assessment.

(4) Bisulfite Conversion Efficiency Assessment: Conversion efficiency evaluated through non-CpG context analysis.

(5) CpG Coverage Statistics: Number and proportion of target region CpG sites covered.

(6) Methylation Level Analysis: Global methylation levels, methylation distribution across genomic elements, and inter-sample comparison.

(7) Differential Methylation Analysis: DMR identification, differential CpG site screening, volcano plot and heatmap visualization.

Differentially Methylated Region (DMR) Results — Example

Differentially Methylated CpG Site Results — Example

Figure 3. Volcano plot, heatmap, and summary statistics of differential methylation analysis

(8) Key Gene Visualization: Methylation pattern visualization of critical genes and comparison with reference databases.

Figure 4. Bar chart of key gene methylation levels and methylation level change curves

(9) Raw Data: Methylation raw data tables and coverage information are provided to support further downstream analysis.

6. Targeted Methylation Capture Sequencing Service Contents

*Service Timeline: Standard workflow 5–7 weeks; expedited service 4 weeks

7. Sample Requirements

*Notes: ① For special samples or custom panels, it is recommended to consult with the technical team in advance to assess feasibility. ② All samples must meet the above quality standards to ensure accuracy and reliability of test results. ③ For special sample types, please contact the GeneRulor technical team in advance (Tel: 400-6309596; Product ordering/technical support: service@generulor.com).

8.References

[1] Lee, E. J., et al. (2011). Targeted bisulfite sequencing by solution hybrid selection and massively parallel sequencing. Nucleic Acids Research, 39(19), e127.

[2] Ivanov, M., et al. (2013). In-solution hybrid capture of bisulfite-converted DNA for targeted bisulfite sequencing of 174 ADME genes. Nucleic Acids Research, 41(6), e72.

[3] Shen, L., et al. (2013). Genome-wide profiling of DNA methylation reveals a class of normally methylated CpG island promoters. PLoS Genetics, 9(4), e1003388.

[4] Mulqueen, R. M., et al. (2018). Highly scalable generation of DNA methylation profiles in single cells. Nature Biotechnology, 36(5), 428–431.