221: Allele-resolved nanopore tour of the human placental methylome

Kindlova M et al., Nat Commun - Using phased long-read nanopore and short-read sequencing across eight trios, the study maps allele-specific DNA methylation and transcription in female human placentas, identifies hundreds of DMRs and novel imprinted genes, and reports somatic placental variants. Key terms: placenta, nanopore sequencing, DNA methylation, imprinting, allele-specific expression.

Study Highlights:
The authors combined >20x Oxford Nanopore whole-genome sequencing with Illumina WGS and RNA-seq in eight mother–father–placenta trios to phase reads into maternal and paternal alleles. They catalogued 723 differentially methylated regions, finding a strong bias toward paternal demethylation concentrated in partially methylated domains. Allele-resolved expression analysis identified 74 imprinted genes and revealed previously unreported imprinted loci including paternally expressed ILDR2 and maternally expressed RASA1. The study also detected widespread somatic point mutations and a small number of placenta-specific structural variants, including a CNDP1–ZNF407 duplication associated with altered gene expression

Conclusion:
Phased nanopore sequencing provides a high-resolution, allele-specific map of the placental methylome and transcriptome, revealing novel imprinted genes and somatic variation with potential relevance to placental biology

Music:
Enjoy the music based on this article at the end of the episode.

First author:
Kindlova M

Journal:
Nat Commun

DOI:
10.1038/s41467-025-65337-3

Reference:
Kindlova M, Byrne H, Kubler JM, Steane SE, Whyte JM, Borg D, Clifton VL & Ewing AD. An allele-resolved nanopore-guided tour of the human placental methylome. Nat Commun. 2025;16:10358. https://doi.org/10.1038/s41467-025-65337-3

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-12-07.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Substantively audited the transcript’s coverage of allele-resolved placental methylome mapping, DMRs, imprinting, specific imprinted genes ILDR2 and RASA1, the C19MC locus, SST1 repeats, somatic variation including CNDP1–ZNF407, and X-chromosome methylation, plus study limitations and conclusions.
- transcript topics: Allele-resolved methylome mapping by nanopore sequencing; Trio-based phasing and parental allele assignment; Global methylation patterns and PMDs in placenta; Differentially methylated regions (DMRs) and paternal demethylation bias; Imprinted genes ILDR2 and RASA1; C19MC locus and SST1 macro-satellite region

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 8
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- Eight female placentas were sequenced in eight mother–father–placenta trios
- Long-read nanopore sequencing with trio-based phasing enables allele-specific methylation and transcription mapping, with EM-seq validation showing high concordance (~94%)
- Identified 723 differentially methylated regions (DMRs), including 184 novel DMRs
- Large majority of DMRs show paternal demethylation bias
- ILDR2 is paternally demethylated and expressed; RASA1 is maternally demethylated and expressed
- C19MC locus encodes paternally expressed miRNAs; SST1 macro-satellite region shows paternal methylation pattern with transcription initiated at a HERVH element

QC result: Pass.