One-Person Trial, Death One Week Later: China Brain Gene-Editing Case Exposes Safety and Regulatory Gaps

Precisely rewriting a single DNA letter was intended to offer hope tailored to families affected by rare diseases. But when a treatment has only one participant, any underestimated risk may leave no second chance for correction. The death of a six-year-old girl in China after receiving a brain gene-editing treatment has now brought the most difficult safety, ethical, and information-transparency issues surrounding “one-person therapies” to the forefront.

Shanghai Jiao Tong University School of Medicine said it has established a special working group to conduct a comprehensive investigation into a paper published by its researchers and a single clinical study carried out at its affiliated Xinhua Hospital, and that it will take serious action based on the investigation’s findings. According to combined media investigations, the girl, identified by the pseudonym “Mei,” received an intrathecal injection in March 2025 and died amid a severe immune response about one week later. The university has not yet released the conclusions of an independent investigation, so the treatment procedures, determination of the cause of death, and responsibility of the personnel involved remain to be confirmed.

The girl had Snijders-Blok-Campeau syndrome, which is caused by a variant in the CHD3 gene and can lead to developmental delay and impairments in speech and cognition. The experimental therapy used two sets of adeno-associated viral vectors to deliver an adenine base editor in an attempt to correct the R1025W mutation. Base editing does not require cutting both strands of DNA, but that does not mean the overall treatment is free of high risks. When large quantities of viral vectors are injected directly into the cerebrospinal fluid, immune toxicity and systemic organ reactions may still pose major dangers.

An animal study published in *Nature* in February this year showed that the therapy could improve some behavioral abnormalities in humanized mice and broadly enter neurons after intrathecal injection in nonhuman primates. However, independent experts, citing related investigations, said that liver and kidney safety signals had appeared in four primates, raising questions about whether these findings had been adequately evaluated and disclosed to the family. These allegations still await verification by the university and the journal, but they have already highlighted the enormous gap between “being able to reach the brain” and “being safe enough for use in humans.”

The public trial registration NCT06860672 lists the study as an early Phase 1 trial expected to enroll only one child between two and ten years old, primarily to assess safety, tolerability, and preliminary efficacy. The record was last updated in March 2025; after the participant reportedly died, the page continued to show that recruitment was ongoing. For a study with only one participant, failure to promptly update a serious adverse event prevents other families, ethics reviewers, and researchers from seeing the most critical risk information.

The related animal paper also did not mention that the girl had received the treatment or that she had died. On July 29, *Nature* added an editor’s note stating that concerns had been raised about the paper and its data and that further editorial action might be taken after the investigation was completed. The note is neither a retraction nor a finding of misconduct, but it indicates that the controversy has extended from clinical oversight to data integrity and academic disclosure.

The central issue in this case is not merely whether base editing itself failed, but how the evidentiary threshold should be set before treatment in humans, how animal toxicity should be interpreted, whether the family received a complete explanation of the risks, and whether a fatal outcome can be disclosed rapidly. The university’s investigation must still address ethics review, dose selection, viral-vector quality, serious adverse-event reporting, and disclosure in the paper. Until answers emerge, any judgment about individual wrongdoing or the precise mechanism of death should remain cautious.