Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis

Background: Epigenetic biomarkers, particularly CpG methylation, are increasingly employed in clinical and forensic settings. However, we still lack a cost-effective, sensitive, medium-scale method for the analysis of hundreds to thousands of user-defined CpGs suitable for minute DNA input amounts (...

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Main Authors: Roy B. Simons, Hieab H. H. Adams, Manfred Kayser, Athina Vidaki
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Epigenomes
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Online Access:https://www.mdpi.com/2075-4655/9/1/8
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author Roy B. Simons
Hieab H. H. Adams
Manfred Kayser
Athina Vidaki
author_facet Roy B. Simons
Hieab H. H. Adams
Manfred Kayser
Athina Vidaki
author_sort Roy B. Simons
collection DOAJ
description Background: Epigenetic biomarkers, particularly CpG methylation, are increasingly employed in clinical and forensic settings. However, we still lack a cost-effective, sensitive, medium-scale method for the analysis of hundreds to thousands of user-defined CpGs suitable for minute DNA input amounts (<10 ng). In this study, motivated by promising results in the genetics field, we investigated single-molecule molecular inversion probes (smMIPs) for simultaneous analysis of hundreds of CpGs by using an example set of 514 age-associated CpGs (Zhang model). Methods: First, we developed a novel smMIP design tool to suit bisulfite-converted DNA (Locksmith). Then, to optimize the capture process, we performed single-probe capture for ten selected, representative smMIPs. Based on this pilot, the full smMIP panel was tested under varying capture conditions, including hybridization and elongation temperature, smMIP and template DNA amounts, dNTP concentration and elongation time. Results: Overall, we found that the capture efficiency was highly probe-(and hence, sequence-) dependent, with a heterogeneous coverage distribution across CpGs higher than the 1000-fold range. Considering CpGs with at least 20X coverage, we yielded robust methylation detection with levels comparable to those obtained from the gold standard EPIC microarray analysis (Pearsons’s r: 0.96). Conclusions: The observed low specificity and uniformity indicate that smMIPs in their current form are not compatible with the lowered complexity of bisulfite-converted DNA.
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spelling doaj-art-6dfec6ced4644a449bfc857b7acc58362025-08-20T02:42:32ZengMDPI AGEpigenomes2075-46552025-03-0191810.3390/epigenomes9010008Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation AnalysisRoy B. Simons0Hieab H. H. Adams1Manfred Kayser2Athina Vidaki3Department of Genetic Identification, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The NetherlandsDepartment of Clinical Genetics, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The NetherlandsDepartment of Genetic Identification, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The NetherlandsDepartment of Genetic Identification, Erasmus MC, University Medical Center Rotterdam, 3015 GD Rotterdam, The NetherlandsBackground: Epigenetic biomarkers, particularly CpG methylation, are increasingly employed in clinical and forensic settings. However, we still lack a cost-effective, sensitive, medium-scale method for the analysis of hundreds to thousands of user-defined CpGs suitable for minute DNA input amounts (<10 ng). In this study, motivated by promising results in the genetics field, we investigated single-molecule molecular inversion probes (smMIPs) for simultaneous analysis of hundreds of CpGs by using an example set of 514 age-associated CpGs (Zhang model). Methods: First, we developed a novel smMIP design tool to suit bisulfite-converted DNA (Locksmith). Then, to optimize the capture process, we performed single-probe capture for ten selected, representative smMIPs. Based on this pilot, the full smMIP panel was tested under varying capture conditions, including hybridization and elongation temperature, smMIP and template DNA amounts, dNTP concentration and elongation time. Results: Overall, we found that the capture efficiency was highly probe-(and hence, sequence-) dependent, with a heterogeneous coverage distribution across CpGs higher than the 1000-fold range. Considering CpGs with at least 20X coverage, we yielded robust methylation detection with levels comparable to those obtained from the gold standard EPIC microarray analysis (Pearsons’s r: 0.96). Conclusions: The observed low specificity and uniformity indicate that smMIPs in their current form are not compatible with the lowered complexity of bisulfite-converted DNA.https://www.mdpi.com/2075-4655/9/1/8age predictioncaptureDNA methylationepigeneticspadlock probessingle-molecule molecular inversion probes
spellingShingle Roy B. Simons
Hieab H. H. Adams
Manfred Kayser
Athina Vidaki
Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
Epigenomes
age prediction
capture
DNA methylation
epigenetics
padlock probes
single-molecule molecular inversion probes
title Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
title_full Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
title_fullStr Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
title_full_unstemmed Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
title_short Investigating Single-Molecule Molecular Inversion Probes for Medium-Scale Targeted DNA Methylation Analysis
title_sort investigating single molecule molecular inversion probes for medium scale targeted dna methylation analysis
topic age prediction
capture
DNA methylation
epigenetics
padlock probes
single-molecule molecular inversion probes
url https://www.mdpi.com/2075-4655/9/1/8
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AT hieabhhadams investigatingsinglemoleculemolecularinversionprobesformediumscaletargeteddnamethylationanalysis
AT manfredkayser investigatingsinglemoleculemolecularinversionprobesformediumscaletargeteddnamethylationanalysis
AT athinavidaki investigatingsinglemoleculemolecularinversionprobesformediumscaletargeteddnamethylationanalysis