Publications
Science advancesMar 2025 |
11
(
13
),
eadu7334
DOI:
10.1126/sciadv.adu7334

Systematic high-throughput evaluation reveals FrCas9's superior specificity and efficiency for therapeutic genome editing

Tian, Rui; Tian, Xun; Yang, Meiying; Song, Yuping; Zhao, Tingting; Zhong, Chaoyue; Zhu, Wei; Zhou, Ping; Han, Zhiqiang; Hu, Zheng
Product Used
Variant Libraries
Abstract
CRISPR-Cas9 systems have revolutionized genome editing, but the off-target effects of Cas9 limit its use in clinical applications. Here, we systematically evaluate FrCas9, a variant from Faecalibaculum rodentium, for cell and gene therapy (CGT) applications and compare its performance to SpCas9 and OpenCRISPR-1. OpenCRISPR-1 is a CRISPR system synthesized de novo using large language models (LLMs) but has not yet undergone systematic characterization. Using AID-seq, Amplicon sequencing, and GUIDE-seq, we assessed the on-target activity and off-target profiles of these systems across multiple genomic loci. FrCas9 demonstrated higher on-target efficiency and substantially fewer off-target effects than SpCas9 and OpenCRISPR-1. Furthermore, TREX2 fusion with FrCas9 reduced large deletions and translocations, enhancing genomic stability. Through screening of 1903 sgRNAs targeting 21 CGT-relevant genes using sequential AID-seq, Amplicon sequencing, and GUIDE-seq analysis, we identified optimal sgRNAs for each gene. Our high-throughput screening platform highlights FrCas9, particularly in its TREX2-fused form, as a highly specific and efficient tool for precise therapeutic genome editing.
Product Used
Variant Libraries

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