Guide RNA length shapes base editor activity in human globin genes
A preprint released on 13 September shows that the length of the guide RNA determines which nearby DNA letters a base editor can modify in human cells. The study focused on the beta‑ and gamma‑globin genes, where changing the guide length altered both editing efficiency and the pattern of nucleotide changes.
In the beta‑globin region targeting the HbE mutation, the desired change occurs at nucleotide A9 while the adjacent A10 can generate the Hb Aubenas variant. With a 15-nt guide, A9 was edited most frequently and the ratio of A10 to A9 edits was about ~3%.
For the gamma‑globin target, the shortest guide length that yielded detectable editing depended on how the editor was delivered. In HUDEP‑2 cells that continuously produced the editor, a 15-nt guide gave measurable editing, whereas after transient delivery in HUDEP‑2 and primary progenitors editing began only with a 17-nt guide.
Because the globin genes are similar, Cas9 can cut both sites, a situation linked in the group’s 2024 work to large deletions between them. PCR assays for the deletion products did not detect the expected fragments when using guides of 15–16 nt, and a nickase version (dABE8e) gave higher editing frequencies than the standard ABE8e with a 16‑nt guide.
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bioRxiv
Guide RNA truncation as a tunable approach for modulating base editing outcomes
Base editing enables programmable nucleotide conversion but can be limited by bystander editing and unintended genomic alterations. Here, we investigated guide RNA (gRNA) truncation as a strategy to modulate base editing outcomes. On editing across multiple…
September 17, 2026 13
