Gene Therapy · asia
Six-Year-Old Girl Dies After Brain Base Editing, Undisclosed Case Shakes Trial Oversight
A dual-AAV gene-editing therapy developed for a single patient was followed by a fatal immune response seven days after injection; the death, family funding, and trial results were not disclosed promptly, and the related animal study is now under investigation by Nature.
An experiment originally intended to push the boundaries of rare disease treatment has now become a warning for gene-editing governance. A joint investigation by Science and Retraction Watch found that a six-year-old girl in China died seven days after receiving an experimental base-editing therapy targeting the brain. The serious outcome remained undisclosed for more than a year, and the clinical trial registry reported neither the patient’s death nor the study results.
The girl had Snijders Blok–Campeau syndrome caused by a CHD3 variant, which can lead to impairments in language, cognitive, and motor development. The research team attempted to correct her CHD3-R1025W variant by splitting a base editor between two adeno-associated viral vectors and injecting them through the cerebrospinal fluid, allowing the two components to enter neurons and reassemble. According to the investigative report, the treatment used a large quantity of viral vectors, after which the girl developed a severe immune response related to the therapy and died.
This was an open-label, early phase 1 trial expected to enroll only one child. ClinicalTrials.gov lists drug-related serious adverse events as a primary outcome measure, names Yu Yongguo as the sponsor, and names Yu Yongguo and Qiu Zilong as principal investigators. However, the registry record has not been updated since March 6, 2025, still shows the trial as recruiting, and contains no published results. Shanghai Jiao Tong University has said it is investigating the case involving Qiu Zilong and its affiliated Xinhua Hospital. According to the South China Morning Post, the hospital had previously been fined approximately RMB 24,000 by local health authorities.
Another line of controversy surrounding the case leads to an animal study published in Nature in February this year. The paper showed that researchers corrected the target base in mice carrying the corresponding CHD3 variant, restored some protein expression, and improved behavioral abnormalities. Following intrathecal administration in nonhuman primates, the dual AAV system also broadly transduced neurons and reassembled the editor. However, these results primarily demonstrated the feasibility of delivery and editing and could not directly establish a human dose, immune tolerability, or clinical benefit.
The paper did not describe the human trial or its fatal outcome, nor did it disclose the patient family’s substantial financial support for developing the therapy. Retraction Watch reported that the family raised approximately US$860,000 through savings and contributions from relatives and friends. The family has now requested that the paper be retracted. According to information cited by El País, an internal hospital investigation attributed the death to the therapy, while other experts said warning signs in the mouse and monkey experiments should have prompted the team to conduct additional safety testing. These claims still require full clarification through investigations by the university, hospital, and journal.
Nature added an editor’s note on July 29 stating that concerns had been raised about the paper and the data it presented, that the journal was investigating, and that further action might follow. This does not mean the paper has been retracted or that the related allegations have received a final determination. It does, however, indicate that the issues extend beyond clinical reporting to research funding, conflict disclosures, how animal evidence is used to support human trials, and whether journals can identify clinical events directly related to a paper during peer review.
In highly personalized “n-of-1 trials,” a patient may be both the only participant and a major funder of therapy development, tightly intertwining medical choices, research judgment, and financial relationships. If deaths and other serious adverse events are not entered promptly into registry systems, reported to regulators, and recorded in academic publications, other research teams cannot learn from the risks, and subsequent families cannot be truly informed. Investigations have yet to determine ultimate responsibility in this case, but it has already made one point clear: the closer a technology comes to irreversibly rewriting human cells, the less transparency and independent oversight can be left until after the fact.