Base Editing, Prime Editing, and Next-Generation Precision Tools
Beyond Double-Strand Breaks
Motivation
Double-strand breaks can be efficient but also introduce unwanted indels, translocations, or p53-associated stress, motivating alternative precision-editing strategies.
Precision editing tools
Cytosine/adenine base editors
- Single-base conversions
- No classical double-strand break
- Context dependent and sequence constrained
Prime editors
- Programmable substitutions and small insertions/deletions
- Uses a reverse transcriptase-linked targeting system
- Broad but more complex design
A major advantage of base editing is that it can:
Base editors allow targeted base conversion while avoiding a DSB.
Correct answer: Change a nucleotide without making a double-strand break
Why is prime editing often described as more flexible than simple base editing?
Prime editing can introduce substitutions, insertions, and deletions.
Correct answer: Because it can program a wider range of sequence changes than single-base conversions
Engineering Constraints
Practical limits
Editing windows, bystander effects, pegRNA design, reverse transcriptase efficiency, and local sequence context all constrain performance.
Trade-offs among precision tools
| Tool | Strength | Main limitation |
|---|---|---|
| Base editor | Efficient single-base conversion | Restricted editing window and bystander edits |
| Prime editor | Versatile sequence rewriting | Complex design and variable efficiency |
| RNA editor | Temporary effect | No permanent genomic change |
Which limitation is especially relevant to base editing?
Nearby bases in the editing window can be unintentionally modified.
Correct answer: It can produce bystander edits within the editing window
State one advantage of RNA editing over DNA editing.
This can be useful for transient therapeutic or research applications.
Correct answer: It is reversible and does not permanently change the genome