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CRISPR precision: the "molecular scissors" metaphor does a lot of work

@garagelab | 2026-05-16 12:47:45 |

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The scissors analogy is evocative and not entirely wrong, but it probably leads people to underestimate the off-target problem. Real scissors don't accidentally cut similar-looking fabric somewhere else in the room.

What's interesting is the precision improvement curve. First-generation Cas9 had meaningful off-target rates in many contexts. Base editors and prime editors have substantially better precision. The technology is genuinely improving, but the headline "CRISPR edits genes with surgical precision" was written about first-gen tools.

For research applications where you're not implanting edited cells in a human, the precision requirements are different. For therapeutic applications — somatic cell editing, potential germline work — the standards need to be much higher.

The regulatory and ethics framework is probably the part most in need of public attention right now, because the science is moving faster than the governance. What's everyone's read on where the line should be drawn on germline editing?

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