Shanghai Jiao Tong University School of Medicine has launched an investigation into a case in which a 6-year-old girl who received a brain gene-editing procedure at an affiliated university hospital died after a week but the incident was concealed for more than a year. The international journal Science said on the 27th (local time) that the university promised to take "serious measures" depending on the results of the investigation.
On the 23rd, Science and the research-ethics outlet Retraction Watch exclusively reported that Mei (an alias), a 6-year-old patient with a rare disease, died of a severe immune response after receiving a base-editing procedure from Professor Zilong Qiu in March last year at Xinhua Hospital of the Jiao Tong University School of Medicine. The research team released the results of animal experiments conducted before treatment in Nature in February, but did not disclose the already conducted clinical trial or the patient's death in the paper.
◇ University says it will investigate possible research-ethics violations
In a statement released on the 26th, the Jiao Tong University School of Medicine said it was taking "very seriously the recent online reports regarding the medical research paper released by our researcher Qiu's team and the clinical trial research conducted at our university's affiliated Xinhua Hospital." The statement also said the university "has always attached great importance to research integrity and proper scientific conduct," adding, "We firmly oppose medical research conducted in violation of research ethics and related rules and regulations."
The deceased girl suffered from a rare neurological disorder called "Snijders Blok-Campeau syndrome." It occurs when one base that makes up the CHD3 gene's DNA changes from the normal cytosine (C) base to thymine (T), leading to developmental delays and language and motor impairments. The child was slower than peers in speech and behavioral development and could speak only simple sentences.
DNA is a kind of blueprint that governs all life processes in the human body. Two strands interlock like a zipper to form a double helix, and the "teeth" of the zipper are the four bases A (adenine), G (guanine), C, and T. Genetic diseases arise when the order of these bases differs from normal.
Professor Qiu developed a base-editing therapy that restores the patient's mutated gene to normal. Base editing advances the CRISPR-Cas9 used in conventional gene editing. CRISPR-Cas9 is an RNA-enzyme complex that cuts only the desired part of DNA for correction.
Unlike conventional CRISPR-Cas9, which cuts both DNA strands to replace the mutated part with normal, base editing is a technique that chemically changes only a specific base. It is akin to correcting a single typo rather than rewriting the entire sentence.
◇ Procedure proceeded despite side effects in animal tests
In March last year, Qiu's team injected trillions of viral particles containing the base-editing therapy into Mei's brain cells. The base-editing therapy consists of genetic material that locates the problematic DNA, a DNA-cutting enzyme, and a base-conversion enzyme. The researchers inserted the genetic blueprint for this into a harmless viral genome.
The researchers expected that once the virus entered the body, the base-editing therapy would be synthesized and travel to the problematic mutant gene to change a single base. But immediately after the procedure, Mei suffered from a high fever and inflammation and died seven days later. According to Xinhua Hospital's mortality review committee, the viruses triggered a fatal immune response.
Science said it appears the hospital did not verify safety data from prior monkey experiments when it approved the clinical trial. Qiu reported in Nature in February that the base-editing therapy effectively corrected the same mutant gene as Mei's in human cells and in the brains of mice and monkeys, but did not disclose Mei's death or the side effects observed in monkeys.
Mei's parents provided Science with a research report and documents related to the clinical trial showing that the base-editing therapy caused severe organ damage in four monkeys. The parents also released information showing they paid $860,000 (about 1.2 billion won) as development costs for the therapy despite the trial being for research purposes, along with audio recordings of conversations with the medical staff.
Experts raised questions about the efficacy and safety of the base-editing therapy used on the patient. Seven experts who reviewed the animal experiments and the clinical trial at Science's request said the warning signs seen in animal studies were not sufficiently examined. Some experts said it should not have entered a human clinical trial in the first place.
Qiu is not responding to media interview requests. The South China Morning Post in Hong Kong reported on the 26th that Qiu said, "All answers will be provided by the medical school leadership."
References
Science (2026), DOI: https://doi.org/10.1126/science.zbr2v4d
Nature (2026), DOI: https://doi.org/10.1038/s41586-026-10113-6