Science & technology | One of a kindFor the first time, a CRISPR drug treats a child’s unique mutationScientists hope more children will benefitPhotograph: Children's Hospital of Philadelphia May 15th 2025WITHIN DAYS after KJ was born in Philadelphia in August 2024 it was clear that something was wrong. He was not eating and slept too much. Blood tests revealed sky-high levels of ammonia, a toxic substance the body usually expels. Genome sequencing confirmed that he had a rare genetic disease called carbamoyl-phosphate synthetase 1deficiency, which often kills in infancy, and for which no good neonatal treatment exists. Then one of his doctors suggested something radical: a gene-editing drug designed specifically for him.Explore moreThis article appeared in the Science & technology section of the print edition under the headline “One of a kind”From the May 17th 2025 editionDiscover stories from this section and more in the list of contents⇒Explore the editionReuse this content #first #time #crispr #drug #treats