Exclusive: Death of girl in Chinese gene-editing trial was never made public

A version of this story appeared in Science, Vol 393, Issue 6809.Download PDF The young girl tugged on her mother’s hand as they pressed through the doors of the hospital in Shanghai. She was 6 years old, bouncing along in a pink jacket and blue pants decorated with cartoon bears. Behind them, her father rolled a large suitcase with everything the child needed for the weeklong stay: stuffed animals, Play-Doh, an iPad loaded with episodes of Peppa Pig. She told her parents it felt like they were going on vacation. In fact, they brought her here for an experimental gene therapy. The girl was slipping behind her peers in kindergarten. She still spoke in simple sentences and ate with training chopsticks. Underneath it all was a single mutated DNA base, a T that should have been a C. “Your ‘book’ has a small mistake, which has caused you to have a disease that affects your growth,” read the children’s version of the informed consent form from the hospital. “Over time, it can get more serious.” Doctors hoped to repair that mistake while her brain was still building itself. It would be a clinical trial of one, funded in part by $860,000 the parents had scraped together from their own savings and from relatives. The parents felt they were in good hands. Xinhua Hospital, which is affiliated with the Shanghai Jiao Tong University School of Medicine, was acclaimed for its pediatrics department. It was the first Chinese institution to perform open heart surgery on infants, and the first in the country to separate conjoined twins. If all went well, the hospital would make history once again. The girl would be the first person in the world to receive a gene-editing therapy directed at the brain. It would rewrite the mutated gene in her neurons, restoring the needed DNA base so she could make a vital protein. Leading the effort was Zilong Qiu, a neuroscientist at the university’s brain center, the Songjiang Research Institute. At the time, in late March 2025, Qiu was one of several researchers around the world vying to push base editors—a more precise form of the powerful gene editor CRISPR—into custom treatments for children with rare diseases.

One month earlier, KJ Muldoon, an infant with a life-threatening metabolic disorder, had quietly received his first intravenous infusion of one such treatment at the Children’s Hospital of Philadelphia. Although news that base editing saved “Baby KJ” would soon rocket around the world—Science named the feat one of the runners-up for its 2025 Breakthrough of the Year—the story of what happened at Xinhua Hospital has remained hidden. An entry for the study posted to ClinicalTrials.gov has not been updated for more than a year. And when Qiu and his colleagues published proof-of-concept animal studies related to the trial in Nature early this year, they stripped the paper of references to the family and its financial contributions, noting only that “bridging the gap between preclinical research and clinical translation remains a significant challenge.” That vague language glossed over tragedy: Seven days after the girl’s medical team infused trillions of viruses carrying the recipe for the base editor into her spinal fluid, she died of a severe immune reaction linked to the therapy, Science and Retraction Watch can now reveal. According to official documents and accounts provided by the girl’s parents, the hospital had allowed Qiu’s experimental treatment to proceed under a regulatory provision that does not require approval from national regulators. After the child’s death, the hospital paid a modest fine to a local health authority but Qiu was not publicly sanctioned. The troubling death represents a new stumble in China’s push to rival the United States as a biotech power. Three years ago, the government strengthened its biomedical research rules in response to the 2018 scandal around He Jiankui, a biophysicist who violated ethical norms to secretly produce gene-edited babies. The lax oversight of this recent trial and the failure to publicly report the fatality “shows the gap between what is intended and what has been put in place,” says Joy Zhang, a sociologist at the University of Kent who has written about the pervasive culture of secrecy in Chinese scientific institutions. Seven experts in fields including genetics, virology, and bioethics who reviewed details of the Nature study and the clinical trial for Science and Retraction Watch expressed concern that Qiu and his team downplayed the trial’s risks in describing them to the parents, overlooked safety signals in animal studies, and proceeded even though success was unlikely. “

This shouldn’t have gone to trial,” says Steven Gray of the University of Texas Southwestern Medical Center, who develops viruses for gene therapy. Gray and several of the other experts are calling for a full review of the images and other data in submitted and published versions of the Nature paper and full disclosure of the study’s funding. Some of the issues might warrant a retraction, they say. Neither Qiu nor his university or the hospital responded to multiple requests for comment for this story, and Nature says it was not aware of the issues surrounding the clinical trial before it published the group’s paper. The girl’s parents, who requested that Science use pseudonyms for them and their daughter for privacy reasons, have decided to tell her story now because they are angry about what they feel is a lack of accountability by the researchers and the institutions. “Learning the reality of these missing safeguards has fundamentally changed how we now view the entire project,” says the father, a software engineer. He asked that he be called Jason, his wife Linda, and their daughter Mei (Chinese for “beautiful”). “We did not realize how unusual and dangerous many of the arrangements were.” As with Jesse Gelsinger, the 18-year-old whose death during an early U.S. gene therapy trial in 1999 chilled research in the field for nearly a decade, Mei’s story raises questions about whether such risky treatments should be initially tested on patients with nonfatal conditions. “I don’t think these kinds of experiments should stop, but we need to make sure we are appropriately careful about them,” says bioethicist Hank Greely, director of the Center for Law and the Biosciences at Stanford University. “It’s so easy to be blinded by hope—whether it’s hope for your kid, hope for your research, or hope for your company.” Jason and Linda had been trying to have a child for 4 years before Mei was born in early 2019. They marveled at every milestone: her first words, her first steps. She did seem a little clumsier than other toddlers. But within a few years, she was attending Parkour classes and bouncing on a neighborhood trampoline. When Mei was 4, one of her kindergarten teachers pulled Linda aside: Mei didn’t draw or write as well as the other kids and her language skills weren’t developing normally. Her mother might want to get her evaluated, the teacher said.

In March 2023, Mei was diagnosed with global developmental delay, a broad label with many causes. Specialists explained that some of Mei’s behaviors—the funny sounds she liked to make, for instance—were associated with autism. The family followed up with a battery of tests at the Shanghai Children’s Medical Center. A brain MRI, chromosome analysis, and a test panel for genes known to influence neurodevelopment all came back normal. Detailed sequencing of more of Mei’s DNA finally pointed toward the delay’s root cause: a defect in a gene, called CHD3, that influenced how strands of DNA were wound into chromosomes inside Mei’s cells. This packing affects how well other genes are expressed, including those involved in the early development of the brain. By altering gene activity, CHD3 mutations produce a condition called Snijders Blok-Campeau syndrome that is known to afflict just 237 individuals around the world. Philippe Campeau, a medical geneticist at the University of Montréal who helped identify the syndrome’s genetic basis in 2018, says people with the mutation often have a normal life expectancy, but their symptoms vary widely. Most have slightly larger than normal heads, and about two-thirds have intellectual deficits. Moderate to severe cases may be nonverbal, suffer from seizures and heart problems, and have fluid-filled voids in their heads. For those patients, gene-editing therapies could be revolutionary, according to Campeau. “For somebody who is just mildly affected … that’s a bit more debatable,” he says. Mei sat on the milder end of the gradient, but Linda soon quit her job to devote her energy to their only child. She and Jason took Mei to speech and occupational therapists and got her special education support. It worked, to a degree. After they transferred Mei to another kindergarten to repeat a year, most of the other parents weren’t even aware of her condition, they said. Whereas Linda was an optimist by nature, Jason feared the worst. The condition is not degenerative, but the gap between Mei and her peers in school would likely widen as courses grew harder. She was also skinnier than other children and had poor muscle tone. She might not ever be able to live independently. “We were worried about her future,” Jason says. After Mei’s diagnosis in 2023, the family joined a private WeChat group in which parents of children with autism and similar disorders trade advice.

It was there that they first heard about Qiu. An expert in neurodevelopmental disorders, he did his Ph.D. at the Shanghai Institute of Biochemistry and Cell Biology and, like many promising Chinese students of his generation, went to the U.S. for a postdoctoral position. In 2003, he joined the laboratory of Anirvan Ghosh, a neuroscientist then at the University of California (UC) San Diego, who found Qiu to be “talented and motivated.” In 2009, as China was ramping up efforts to lure its scientists back home, Qiu took a post at his undergraduate alma mater. He published in all the right places—Nature, Neuron, and the Proceedings of the National Academy of Sciences. He also strove to demystify genetics for the Chinese public with a book, The Gene Enlightenment, and through public lectures, including a TEDx talk titled “Defying the destiny dictated by our genes.” Qiu was among more than 100 Chinese scientists who condemned He’s rogue embryo gene editing in an open letter. “The project completely ignored the principles of biomedical ethics, conducting experiments on humans without proving it’s safe,” he told the South China Morning Post. Qiu still saw potential in tackling autismlike conditions that have a clear genetic link, such as Rett syndrome. “He was taken by Rett syndrome and wanted to make a difference,” says Monica Coenraads, CEO of the Rett Syndrome Research Trust, which funded some of Qiu’s research in the U.S. Neuroscientist Zilong Qiu, speaking here in 2015 at a science fiction convention, was confident in the safety of a gene-editing treatment he developed, but it led to a death that was not made public.LI YIBO/XINHUA/ALAMY For parents in the WeChat group, Qiu was someone to watch. His gene therapy for Rett syndrome had recently been patented in China, and he founded a company, Lanqi Xintu Gene Technology, which would soon bring it into the clinic for testing. In July 2023, he gave a lecture about this work and other efforts. A parent from the group attended, and posted slides. The following week, Jason sent Qiu an email describing Mei’s condition. “