420: NOTCH2NL duplications: diversity, regulation, and human-specific changes

Real TD et al., Cell Genomics - This episode examines a long-read sequencing study that resolves the complex NOTCH2NL segmental duplications on human chromosome 1, traces independent duplications in apes, documents gene conversion and structural variation across human haplotypes, and maps paralog-specific regulatory elements using Fiber-seq and long-read transcriptomics in brain organoids. Key terms: NOTCH2NL, segmental duplications, gene conversion, chromatin accessibility, brain organoids.

Study Highlights:
Using 82 long-read assemblies from humans and apes, the authors show independent NOTCH2NL duplications among great apes with protein-coding human copies emerging ~2.2–3.7 mya. Analysis of 69 validated human haplotypes defines 11 structural configurations, reveals frequent interlocus gene conversion and a new paralog (NOTCH2tv), and finds NOTCH2NLA present in all haplotypes. Fiber-seq and long-read Iso-Seq in dorsal forebrain organoids identify paralog-specific accessible chromatin elements correlated with differential transcript abundance, with NOTCH2 and NOTCH2NLA harboring the most unique regulatory sites. Functional assays indicate NOTCH2tv and NOTCH2NLR produce unstable proteins, while NOTCH2NLB yields a stable product in HEK293 tests.

Conclusion:
NOTCH2NL loci underwent dynamic duplication, conversion, and regulatory divergence during ape and human evolution; paralog-specific regulatory elements and structural variation likely shaped expression differences while also increasing genomic instability associated with 1q21.1 copy-number disorders. Long-read genomic and epigenomic approaches are essential to resolve these complex regions and their functional implications.

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

Article title:
Genetic diversity and regulatory features of human-specific NOTCH2NL duplications

First author:
Real TD

Journal:
Cell Genomics

DOI:
10.1016/j.xgen.2026.101194

Reference:
Real TD, Hebbar P, Yoo D, et al. Genetic diversity and regulatory features of human-specific NOTCH2NL duplications. Cell Genomics. 2026;6:101194. doi:10.1016/j.xgen.2026.101194

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/

Support:
Base by Base is independent and ad-free — no sponsors, no paywall. If an episode was worth your time, chip in and keep the papers audited and the original songs coming:
❤️ Support monthly: https://buy.stripe.com/cNifZhclVebvagk2JDgEg01
☕ One-time donation: https://donate.stripe.com/7sY4gz71B2sN3RWac5gEg00
More at basebybase.com

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

Episode link: https://basebybase.com/episodes/notch2nl-duplications-regulation

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-07-21.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Audited portions of the transcript covering NOTCH2NL background, independent ape duplications and human copies, interlocus gene conversion (IGC) and the NOTCH2tv paralog, paralog-specific regulatory landscapes (Fiber-seq/FiberFold), organoid transcriptomics, and protein stability assays.
- transcript topics: NOTCH2NL background and brain expansion; Long-read haplotypes and independent duplications; Interlocus gene conversion and NOTCH2tv; Paralog-specific regulatory landscapes and chromatin accessibility; Organoid transcriptomics and protein stability of NOTCH2NL paralogs; Evolutionary timing and limitations of methods

QC Summar...

Chapters

• (00:00:16) - Base by Base: Quantifying genomics
• (00:00:29) - The genetic stutter that built the human brain
• (00:06:54) - Long-read sequencing of the human genome
• (00:12:28) - Interlocus gene conversion in the human genome
• (00:17:57) - Notch2NL and the genetics of the human brain