Key facts
- Two boys in a Chinese gene-editing trial showed improved walking ability.
- One boy withdrew from the trial due to a lack of improvement.
- A fourth boy died 81 hours after receiving the gene-editing drug.
Four seriously ill Chinese boys with a rare inherited disease received an experimental gene-editing drug. More than a year later, the trial has produced contradictory outcomes. Two boys demonstrated improved strength and mobility, while one boy showed no gait improvement and withdrew. The fourth boy died 81 hours after receiving the intravenous medication due to a severe systemic reaction.