Gene editing can only be done to cells removed from the body
The old claim turned out to be wrong and was rejected by evidence.
TaughtCRISPR gene editing works in the lab: you take cells out of a patient, edit them in a dish, and return them. You cannot inject the editing machinery into a living person and have it find and fix the right gene inside the body; that is far too imprecise and dangerous.
NowIn June 2021, Intellia and Regeneron reported in the New England Journal of Medicine the first successful in-vivo CRISPR editing in humans: a single intravenous infusion of NTLA-2001 switched off a disease gene in the livers of patients with transthyretin amyloidosis, cutting the harmful protein by up to 96%.
What actually happened
The distinction is the whole point. Editing cells outside the body (ex vivo) lets you check the results before giving them back; editing inside a living person (in vivo) means the CRISPR tools have to be delivered to the right organ and act precisely on their own. That in-body approach was the one long considered a bridge too far.
The honesty here: this began as an early-phase trial in a small number of patients. But the effect was deep and durable, the program advanced through later-stage trials, and in-vivo CRISPR has since become an established direction rather than a one-off. What was disproved is specific, the claim that gene editing can only be done to cells taken out of the body.
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Who was taught this
Still standard through 2021, so anyone who finished school between 1950 and 2021 learned the earlier version.