Doctors initially prescribed KJ medication to reduce ammonia levels, along with a strict low-protein diet. But waiting months for transplant eligibility carried growing risks of brain injury or death. That\u2019s when Dr. Rebecca Ahrens-Nicklas, a pediatrician and researcher working with a new CRISPR-based technique called base editing, proposed a different path.<\/p>\n
Base Editing: Tested on Humans for the First Time<\/p>\n
Standard CRISPR technology works by cutting DNA entirely at a chosen site. While it\u2019s been used to treat certain genetic diseases, those therapies target groups of patients with similar conditions. KJ\u2019s case required something far more precise \u2014 editing a single genetic \u201cletter\u201d out of three billion in the human genome without severing both strands of DNA. That\u2019s what base editing allows.<\/p>\n
After decades of research \u2014 much of it funded by the U.S. government \u2014 the technique had never been tested on humans. Dr. Ahrens-Nicklas believed it was time. She presented the idea to KJ\u2019s parents, Nicole and Kyle Muldoon, who agreed. Within six months, an international team of scientists and clinicians created a customized therapy<\/a>, encapsulating the genetic material in fatty lipid molecules to ensure it reached the liver safely.<\/p>\n CHOP & @PennMedicine<\/a> have delivered the first-ever personalized gene editing therapy for a patient with CPS1 deficiency, marking a major milestone in the application of CRISPR-based treatments.<\/p>\n Learn more about KJ & the future of personalized medicine: https:\/\/t.co\/A9DTcNmxrR<\/a>. pic.twitter.com\/2LzGiRxGqN<\/a><\/p>\n \u2014 Children’s Hospital (@ChildrensPhila) May 15, 2025<\/a> <\/p>\n An Unprecedented Pace<\/p>\n Developing such a treatment would normally take years. \u201cAchieving clinical-grade CRISPR at this speed for a genetic disease is unprecedented,\u201d said Fyodor Urnov, a molecular therapeutics professor at UC Berkeley.<\/p>\n The first infusion \u2014 a very small dose \u2014 took place on February 25. Soon after, KJ could eat as much protein as a healthy infant, though medication was still required. Twenty-two days later, he received a second infusion. According to Dr. Ahrens-Nicklas, his progress was remarkable: his medication dose was halved, and he overcame viral infections that would typically cause ammonia spikes. A third infusion has since followed. It\u2019s too early to call it a cure, but the doctor says KJ is already showing \u201cearly signs of benefit.\u201d<\/p>\n Although the treatment\u2019s cost can\u2019t be precisely calculated \u2014 many companies offered their expertise for free \u2014 this achievement could redefine medicine. The same method could one day correct DNA mutations unique to individual patients, bringing hope to thousands living with rare genetic diseases<\/a>.<\/p>\n Kiran Musunuru of the University of Pennsylvania summarized it best: \u201cIf we can design a personalized gene-editing therapy for one patient in a matter of months, we can do it for others too.\u201d<\/p>\n Lucie Petit<\/p>\n Journalism student<\/p>\n I\u2019ve been passionate about science since childhood, growing up in the countryside with a strong love for nature. Inspired by my grandfather\u2019s inventive spirit, I developed a curiosity for understanding and sharing knowledge. After earning a science-focused diploma, I chose journalism to make complex topics accessible. I\u2019m now studying at ISCPA in Lyon and interning at Futura, where I\u2019m excited to turn this passion into a profession.<\/p>\n \t\t![\"\"](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/01\/Lucie-Petit-100x100.webp.webp\")
<\/p>\n