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

Sci Adv. 2025 Mar 28;11(13):eadu7334. doi: 10.1126/sciadv.adu7334. Epub 2025 Mar 26.

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.

MeSH terms

  • Animals
  • CRISPR-Associated Protein 9* / genetics
  • CRISPR-Associated Protein 9* / metabolism
  • CRISPR-Cas Systems*
  • Gene Editing* / methods
  • Genetic Therapy* / methods
  • High-Throughput Nucleotide Sequencing
  • Humans
  • RNA, Guide, CRISPR-Cas Systems / genetics

Substances

  • RNA, Guide, CRISPR-Cas Systems
  • CRISPR-Associated Protein 9