TL;DR
Gene editing used to mean cutting DNA, a permanent change. A newer approach leaves the DNA intact and simply turns a gene down, which in principle means the change could one day be undone. That approach now works in people in two different tissues. One infusion held hepatitis B in check for up to 17 months, and another switched off the gene behind a muscle-wasting disease and added muscle in six patients who were expected to lose it. The numbers are small and none of it is approved. But if it holds up, a single shot that quietly dials a bad gene down, rather than a lifetime of pills or a permanent edit, becomes a real option for a widening list of diseases.
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