Targeted genomic integration and rearrangement using prime assembly.

Levesque, Sébastien; Kawashima, Nozomu; Hwang, Gue-Ho; Zeng, Jing; Toskov, Vasil; Barry, Timothy; Mannherz, William; Homfeldt, Luke et al. · Nature · 2026

basic_science · Level V

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Abstract

Although therapeutic genome editing holds great potential to remedy diverse inherited and acquired disorders, targeted installation of medium-to-large genomic modifications in therapeutically relevant cells remains challenging<sup>1</sup>. Here we develop prime assembly, an approach that permits DNA sequence assembly and integration in human cells leveraging CRISPR-targeted dual flap synthesis. This method enables RNA-programmable site-specific integration of single or double-stranded DNA fragments. Unlike homology-directed repair, prime assembly is similarly active in dividing and non-dividing cells. We applied prime assembly to perform targeted exon recoding, transgene integration and megabase-scale rearrangements, including at therapeutically relevant loci in primary human cells. Prime assembly expands the capabilities of genome engineering by enabling the targeted integration of medium to large-sized DNA sequences without relying on double-stranded DNA donors, nuclease-driven double-strand breaks or cell cycle progression.