Santiago Restrepo Castillo

In 2025, a six-year-old Chinese girl named Mei (not her real name) became the first person in the world to undergo gene-editing therapy targeting the brain. She had a developmental delay associated with a rare genetic syndrome, Snijders-Blok-Campeau syndrome. According to Science, her parents had raised $860,000 to partially fund the treatment at Xinhua Hospital in Shanghai (China), led by Zilong Qiu, one of the neuroscientists competing to apply base editors — a version of CRISPR — in children with rare diseases. Now, Science and Retraction Watch have exclusively revealed that Mei died from a severe immune reaction seven days after receiving the treatment, a story that had been kept hidden. The entry on clinicaltrials.gov has not been updated since 2025; and when Qiu and his team published animal studies related to the trial in the journal Nature in early 2026, according to the journalistic investigation, they omitted any reference to Mei and her family.

In 2015, the United Kingdom became the first country to pass legislation allowing the use of mitochondrial donation technology, pronuclear transfer. The technique is designed to limit, through in vitro fertilization, the transmission of mitochondrial DNA diseases in babies born to women who are at high risk, and for which there is no cure. Two studies published in the New England Journal of Medicine (NEJM) describe the results of the first treatments performed to date, from which eight babies have been born by mitochondrial donation, with reduced risk of disease.

A team from the Netherlands has successfully edited pathogenic mutations in mitochondrial DNA in human cells, changes in DNA that cause disease, according to research published in PLoS Biology. The authors used a genetic tool known as a base editor. Until now, techniques derived from CRISPR have made it possible to correct mutations in nuclear DNA, and new techniques are being developed that allow mitochondrial DNA to be edited.