It belatedly emerged that a 6-year-old girl in China who had a rare genetic disease died a week after receiving the world's first brain gene-editing treatment. The researchers released animal test results in the international journal Nature this year ahead of the treatment, but did not disclose the already conducted clinical trial and the patient's death in the paper.
The international journal Science and the research-ethics outlet Retraction Watch reported exclusively on the 23rd (local time) that at Xinhua Hospital affiliated with the Shanghai Jiao Tong University School of Medicine in China, a 6-year-old girl died from a severe immune reaction after receiving a base-editing procedure in March last year. Controversy has grown because they also did not disclose that, despite the trial being for research purposes, the parents covered $860,000 (about 1.2 billion won) in drug development costs.
◇Even the Nature paper released after the death left it undisclosed
DNA is a kind of blueprint that governs all life processes in the human body. Like a zipper, two strands interlock to form a double helix, and the teeth of the zipper correspond to four bases: A (adenine), G (guanine), C (cytosine) and T (thymine). Genetic diseases arise when the order of these bases differs from normal.
The deceased patient suffered from a rare neurological disorder called "Snijders Blok-Campeau syndrome." It is a disease in which one base that makes up the CHD3 gene changes from a normal cytosine base to thymine, causing developmental delay and language and motor impairments. The child's speech and behavioral development lagged behind peers, and the child could speak only simple sentences.
Professor Zilong Qiu developed a base-editing therapy to revert such mutations to normal. Base editing further advances CRISPR-Cas9. Unlike conventional CRISPR-Cas9, which cuts the two DNA strands and replaces the mutated segment with a normal one, it chemically changes only specific bases. It is like correcting a single typo rather than rewriting an entire sentence.
The researchers put the blueprint for the base-editing therapy into an adeno-associated virus (AAV), which is harmless to humans, and sought to deliver it to brain neurons by injecting it into the cerebrospinal fluid. According to a paper released in Nature in February, when the same base-editing therapy was administered to mice with the same CHD3 mutation as humans, CHD3 protein in the brain was restored and abnormalities in cognition, sociability and motor function were alleviated.
Trusting the researchers' explanation, the parents covered $860,000 of the therapy's development costs. In late March last year, the child was admitted to Xinhua Hospital and received the therapy containing billions of viral particles. But high fever and inflammation developed immediately after the procedure, and the child died seven days after administration. According to Science's report, the death was said to be due to a severe immune reaction related to the therapy.
◇Experts: "The clinical trial should not have been done"
Science contacted seven experts in gene therapy, virology and bioethics about the clinical trial. The experts noted that warning signs from animal studies were not sufficiently reviewed. Delivering the therapy across the entire brain required an enormous viral dose, and the actual rate of gene correction was too low to produce therapeutic benefit. Some experts assessed that it should not have entered human clinical testing in the first place.
A bigger problem is that the clinical trial was authorized through a separate system that did not require prior approval from China's national regulators. It is said that a provision allowing exceptional use of innovative treatments with internal hospital approval was applied. On the international clinical trial registry site (ClinicalTrials.gov), the study results and the death were not updated for more than a year.
The parents demanded the retraction of the Nature paper, saying the researchers and hospital did not adequately explain the treatment risks and did not take responsible action after the death. Professor Qiu initially agreed to retract the paper but did not respond to subsequent inquiries. The Jiao Tong University team released animal study results in Nature in February, after the child's death, without mentioning the clinical trial or the parents' financial support.
Nature said it was not aware of issues related to the clinical trial at the time of publication. Experts argued that the paper's raw data and images, animal safety data and funding sources should be thoroughly reexamined. Some pointed out that certain issues could warrant retraction. The Jiao Tong University researchers returned the funds received from the parents.
◇Possibilities remain, and rational regulations must be discussed
China has previously weathered a major controversy over gene editing procedures. In 2018, He Jiankui of Southern University of Science and Technology in Shenzhen announced that three healthy babies were born after he edited a gene at the embryo stage that causes AIDS (acquired immune deficiency syndrome). The method used then was CRISPR-Cas9. Scientists criticized the technology as too dangerous to apply to humans. He served three years in China for illegal medical practices.
China later tightened regulations related to gene editing, but they were not applied to this clinical trial. Science and Retraction Watch said they repeatedly sought comment from Professor Qiu and the university and hospital but received no response. The child's father said, "After learning how lacking the safeguards were, my view of this entire study completely changed," adding, "At the time, I did not realize how unusual and dangerous many of the procedures were."
The scientific community says gene editing and base editing are advancing rapidly and need matching regulation and support policies. Gene editing has already been approved as a therapy for genetic diseases in adults. In 2023, the U.S. Food and Drug Administration (FDA) approved a CRISPR-Cas9-based therapy for sickle cell disease. Last year in the United States, the world's first personalized gene editing was attempted in a 7-month-old baby to treat a rare genetic disease.
Korean and U.S. scientists also succeeded in correcting mutant bases that cause genetic diseases in newly fertilized human embryos. Dieter Egli of Columbia University in the United States; Woo Jae-sung, group leader at the Institute for Basic Science (IBS) Center for Biomolecular and Cellular Structure; and Bae Sang-soo, professor at Seoul National University College of Medicine, reported in June on the preprint site bioRxiv that they had succeeded in correcting bases in mutant genes that cause heart disease and anemia in early-stage human embryos.
The case raised the need to discuss how to manage safety, expense, conflicts of interest and adverse events in single-patient clinical trials, even as personalized gene and base editing offers new possibilities for patients with rare diseases. In particular, the omission of serious adverse events such as death from the paper and clinical trial records has put China's regulators and verification systems at international journals to the test.
References
Science (2026), DOI: https://doi.org/10.1126/science.zbr2v4d
Nature (2026), DOI: https://doi.org/10.1038/s41586-026-10113-6
bioRxiv (2026), DOI: https://doi.org/10.64898/2026.05.30.728989