In a major breakthrough, a patient has been treated with a personalized CRISPR therapeutic that aims to cure their rare genetic disease. This individual, who is known as KJ, was diagnosed with severe carbamoyl phosphate synthetase 1 (CPS1) deficiency at one day old. CPS1 is a rare metabolic disorder in which patients must be placed on a highly restrictive diet to prevent serious health problems from arising. The first CRISPR treatment was administered in February 2025, when KJ was between six and seven months old. So far, the patient is doing very well. The work has been reported in The New England Journal of Medicine. It may help open the doors for open patients with genetic disorders to be treated with CRISPR. CRISPR is a gene editing tool that relies on several things: an enzyme that can cut the genome, a guide RNA molecule that shows the DNA-cutting enzyme where to go, and sometimes, a template that can be used to repair genetic problems that are in the target sequence.