260: TSS hypermutability in human germline linked to RNAP II stalling, R-loops and early embryonic mosaics

Nature Communications - Transcription start sites experience a high influx of heritable variants fueled by early development

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

Article title:
Transcription start sites experience a high influx of heritable variants fueled by early development

Journal:
Nature Communications

DOI:
10.1038/s41467-025-66201-0

License:
CC BY 4.0 International License

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On PaperCast Base by Base you’ll discover the latest in genomics, functional genomics, structural genomics, and proteomics.

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-01-15.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited the transcript for core germline mutagenesis mechanisms around transcription start sites (TSS), mosaic vs de novo variation, mechanistic links (RNAP II stalling, R-loops, divergent transcription), mutational signatures, purifying selection, disease links, and clinical implications as described in the article.
- transcript topics: Germline TSS mutational hotspot; Extremely rare variants and mosaicism; De novo mutations vs mosaic filtering; Transcription-associated mutagenesis mechanisms (RNAP II stalling, R-loops, divergent transcription); Mutational signatures (SBS3, SBS40b, SBS40c; SBS39 maternal clusters; SBS12/SBS16); Divergent transcription at promoters

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:
- Germline transcription start sites harbor a mutational hotspot spanning several hundred base pairs upstream and downstream of the TSS
- Non(CpG > TpG) variations show a mutational excess at the TSS, up to ~35% in 100-bp windows around the TSS
- De novo mutations (DNMs) do not show a significant TSS excess due to misclassification/ filtering; the hotspot is revealed by mosaic variants
- Early mosaic mutations are enriched near the TSS, with a 52% excess immediately downstream of the TSS
- Divergent transcription, RNAP II stalling, and R-loop formation are associated with the TSS hotspot
- Mutational signatures SBS3, SBS40b, SBS40c indicate non-canonical DSB repair; SBS39 linked to maternal mutation clusters

QC result: Pass.

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