Two cases have recently come to light involving the deaths of patients who received gene therapies to treat their diseases.
The first case occurred in 2025 and involved a girl who received gene therapy for Snijders-Blok-Campeau syndrome—caused by a defect in the CHD3 gene—which resulted in mild developmental delay and autism spectrum disorder.
The team used base editors and employed adeno-associated viruses to deliver them into the target cells. Given the large size of these vehicles, the researchers split the genetic instructions between two separate viral vectors.
The girl died seven days after receiving the infusion into her cerebrospinal fluid due to a severe immune reaction caused by the high viral load that was injected into her to deliver the genetic tool.
It was in 2026 that the scientists who had conducted the failed treatment published their successful results in animals in the journal Nature but omitted the information regarding the therapy administered to the girl who had died.
The girl’s parents funded the procedure with $860,000 for the medical team led by Dr. Zilong Qiu, who developed the therapy specifically for her. She was the first person to receive gene-editing therapy in the brain.
A joint investigation by the journals Science and Retraction Watch uncovered the unreported death of this six-year-old girl.
Regulatory framework in China
Three years ago, the Chinese government tightened regulations on biomedical research in response to the He Jiankui scandal, which gained widespread notoriety after he edited the genomes of several human embryos in an effort to make them immune to HIV infection.
Three girls were born—first a set of twins, and then a third girl—according to the researcher himself.
As a result of this experiment, which violated the internationally imposed moratorium on the genetic editing of human embryos intended for gestation, he was sentenced to three years in prison.
After being released, he publicly stated his intention to continue with his experiments.
Gene therapies with fatal outcomes
Qiu, an expert in neurodevelopmental disorders, had patented a gene therapy to treat Rett syndrome and founded a company to develop the technique and apply it in clinical practice. To this end, he had published related scientific papers in the most prestigious scientific journals.
When they decided to contact him and described the girl’s condition, Qiu invited them to visit him at the Songjiang Research Institute of Shanghai Jiao Tong University School of Medicine; there, he explained that he would need to administer viruses into the girl’s cerebrospinal fluid and that it would take about two years to develop the treatment and test it on mice and monkeys, without guaranteeing its effectiveness.
Shortly thereafter, at Qiu’s suggestion—and to fund one of the researchers who was designing the base editor tool he intended to use—her parents made the first bank transfer.
They also paid a company that was set to begin developing the viruses, as well as PriMed, a contract research organization that was to conduct studies on monkeys. Qiu also asked them to make direct payments to other researchers on the team.
One of them, Kan Yang, met with the father and asked him for $130,000, which he deposited directly into his checking account.
Research prior to clinical application
In late 2024, Qiu’s team created mice with a CHD3 gene mutation similar to the one found in the girl. To treat it, they used base editing—a second-generation genetic engineering technique and an evolution of CRISPR-Cas9—which allows for precise single-base changes in DNA.
To design the treatment, they decided to insert the genes for the editing enzyme and the guide RNA into adeno-associated viruses, which can trigger inflammatory responses.
Due to the size of the base editor, the researchers decided to split its genetic instructions—DNA—into two packages and insert them into two different viruses that could be injected simultaneously.
For this to succeed, both viruses had to trigger the expression of the genetic instructions they carried in the same cells throughout the brain.
In 2025, Qiu submitted a manuscript to Nature detailing the preclinical research conducted prior to the personalized therapy for the girl.
One month before the clinical trial with the patient began, the toxicology study conducted on four of the monkeys that received the therapy showed that they had developed liver damage, and that another monkey that received a high dose of the viruses had developed kidney damage.
The clinical trial
On February 19, 2025, the family went to the hospital with the girl to sign the informed consent form and run some tests on her blood.
On the day of the procedure, March 24, 2025, the doctor inserted a needle between two vertebrae in the girl’s lower back and filled the patient’s spinal canal with the viruses that contained the treatment.
Three days after she received the gene therapy, she developed a fever, although the researchers viewed it as a normal reaction to the treatment.
At that moment, Qiu told the parents that his scientific paper had just been accepted by the journal Nature.
Over the following days, the girl’s condition continued to deteriorate, and she was transferred to intensive care, where she ultimately passed away due to thrombotic microangiopathy.
The parents asked Qiu to withdraw his article from Nature, and although he initially agreed, he ultimately did not do so.
Kan Yang returned all the money they had paid him for the treatment research.
In September 2025, the health department fined Xinhua Hospital—where the procedure was performed—$3,600 for failing to oversee the trial and for not registering it as a sponsored study in the commercial database.
The family maintains that they have not been financially compensated for their daughter’s death, even though Qiu had taken out insurance for the trial.
In February, a version of the study was published in Nature with the family’s data removed; although it described a base-editing therapy to treat their daughter’s condition, it presented only data regarding the therapy’s functionality in monkey brains. Experiments on mice—funded by the family—contained biases in the information provided concerning liver and kidney issues in the primates, which were omitted from the publication.
Upon learning of the article’s publication, the parents sent a formal complaint to the university where Qiu works and requested the article’s retraction. Other researchers called for the disclosure of the trial’s funding sources, as their omission constitutes grounds for retraction.
The university’s response was that it would not take any action against Qiu and that the Nature article had no connection to the experiments they had funded.
A second case involving Duchenne muscular dystrophy
The company HuidaGene Therapeutics has announced—a year after the event occurred—that a child died in August 2025 after receiving a dose of the drug HG302.
The minor suffered from Duchenne muscular dystrophy. It was the first time this drug had been tested on humans.
The death occurred after the patient received a very high dose of the medication; since it was unclear whether the treatment was effective at lower doses, the doctors decided to increase the dose.
Muscular dystrophy is caused by a defect in a gene that produces dystrophin, a protein whose primary function is to serve as a stable bridge between the inside and the outside of the muscle fiber.
The team of doctors who treated him has expressed sadness over the patient’s death. Three other patients who participated in the trial have not developed severe clinical syndrome and remain under monitoring.
Bioethical assessment
Experimental gene therapies have yielded very positive results when conducted with due caution and in compliance with the safety procedures mandated by the relevant bodies.
For example, in 2025, an American baby became the first patient treated with a CRISPR therapy fully personalized for his specific genetic mutation—a rare and severe disorder involving a deficiency of the CPS1 enzyme, which is linked to the urea cycle.
Insufficient prior experimentation during preclinical phases creates high-risk environments for the implementation of potential experimental therapies, entailing enormous dangers for patients.
Added to this is the lack of transparency among research teams, who fail to properly document their experiments for audit by other researchers and conceal negative results—particularly when the outcome is death.
The prompt communication of adverse effects associated with scientific research aims to minimize collateral harm to participating patients and to prevent other research teams from repeating procedures that have proven counterproductive.
Economic interests, which appear to be behind the malpractice that has occurred in these cases, create conflicts of interest that can lead to pressure to falsify or conceal data when it is unfavorable.
Only prudent research—which follows a gradual approach to risk-taking, documents its experiments, and promptly reports collateral damage or lack of efficacy—can contribute to scientific progress that is truly progressive by virtue of serving the patients who participate in these trials.
Spurious interests—whether economic or driven by personal advancement—lie behind numerous cases of scientific fraud and malpractice, the consequences of which are always borne most heavily by the most vulnerable.
Julio Tudela and Ester Bosch
Bioethics Observatory – Institute of Life Sciences
Catholic University of Valencia
