Accurate characterization of CRISPR-Cas9 genome editing outcomes and mosaicism with near-perfect long reads.

PureTarget PacBio sequencing reveals extensive genetic mosaicism with up to 18 on-target and 11 off-target variants in individual zebrafish, highlighting widespread editing complexity.

• Why it matters: Understanding mosaicism is crucial for precise genome editing, yet it remains difficult to characterize, especially for low-frequency structural variants, which can impact inheritance and experimental outcomes.
• What they did: Researchers used amplification-free, high-accuracy long-read sequencing on 30 zebrafish samples, achieving over 1100x coverage and enabling detailed analysis of editing outcomes and mosaicism.
• The result: Findings demonstrate that mosaicism is common in CRISPR-Cas9 edited zebrafish, with multiple variants inherited by offspring, emphasizing the need for comprehensive profiling in genome editing studies.