As CRISPR and other genome editing technologies move toward clinical applications, off-target assessment and genome integrity have become essential components of preclinical safety evaluation.
NGS provides a powerful way to detect unintended sequence changes, but reliable results depend on more than sequencing alone. The right detection strategy, library preparation workflow, sequencing platform, and data analysis must work together.
The FDA's April 2026 draft guidance highlights the use of NGS for assessing off-target editing and genome integrity in human genome editing products.
A Typical NGS Workflow for Off-Target Assessment
Off-target assessment generally combines candidate-site discovery, NGS validation, and bioinformatic analysis. Different editing modalities may require different sequencing strategies. No single method can capture every type of unintended event. Combining complementary approaches can provide a more comprehensive assessment.
Figure 1. Conceptual workflow for NGS-based genome editing off-target assessment.
Match the Sequencing Strategy to the Editing Event
Once candidate off‑target sites have been identified, targeted or genome‑wide sequencing is used to verify whether intended and off‑target editing events actually occur. Where applicable, sequencing further characterizes the frequency, allelic distribution, and molecular nature of edits, including insertions, deletions, base substitutions, and large‑fragment rearrangements.
The sequencing strategy should match the expected editing event. Different editing outcomes (indels, base edits, prime‑editing conversions, large structural variants) require distinct sequencing approaches. Choosing a mismatched read‑length, coverage depth or library‑building method risks missing true editing signals or generating false‑positive variant calls. Proper strategy selection ensures reliable quantification of on‑target editing efficiency as well as confident detection of low‑frequency off‑target alterations.
|
Editing Event |
NGS Strategy |
Typical Applications |
|
Small sequence changes |
Short-read sequencing |
SNVs, small indels |
|
Large insertions/deletions |
Long-read sequencing |
Large genomic alterations |
|
Structural variants |
Long-read + complementary analysis |
Translocations, inversions, rearrangements |
|
Epigenome editing |
Methylation sequencing |
Unintended methylation changes |
|
RNA editing |
RNA sequencing |
Transcriptome-level off-target events |
From Off-Target Detection to Sequencing-Ready Libraries
Genome editing safety assessment increasingly requires multiple layers of analysis. Whether the study focuses on small indels, large structural changes, unintended methylation, or RNA-level editing, the sequencing workflow should be matched to the biological question.
Yeasen's NGS solutions help simplify this workflow with:
- DNA → Short- & Long-Read Library Prep
- Epigenome → Methylation Library Prep
- RNA → Strand-Specific RNA Library Prep
- Automation → Standardized, Scalable Library Preparation
Better library preparation. More consistent sequencing data. Greater confidence in genome editing safety assessment.
Related Products
|
Product Category |
Product Name |
Catalog No. |
Notes / Applications |
|
DNA Library Prep |
12927ES |
Short-read sequencing (for ≤50 bp editing detection) |
|
|
13301ES |
Long-read sequencing (Nanopore platform) |
||
|
Epigenetics Library Prep |
12214ES |
WGBS, RRBS |
|
|
SuperMethyl™ Fast Bisulfite Conversion Kit, Magnetic Bead Purification |
17330ES |
Chemical bisulfite conversion |
|
|
RNA Library Prep |
12340ES |
High strand specificity; no light protection required |
|
|
- |
12601ES |
Purification beads (Direct replacement for AMPure XP) |
|
|
- |
12642ES |
dsDNA quantification |
|
|
- |
12645ES |
ssDNA quantification |
References
[1] U.S. FDA. Safety Assessment of Genome Editing in Human Gene Therapy Products Using Next-Generation Sequencing. Draft Guidance for Industry, April 2026.
[2] U.S. FDA. Human Gene Therapy Products Incorporating Human Genome Editing. Guidance for Industry, January 2024.