This baby is the first to be cured by CRISPR. Just one year ago, physicians were uncertain whether infant KJ Muldoon would survive beyond early childhood. Now, he is joyfully taking his first steps—thanks to the world's pioneering single-patient CRISPR gene therapy. KJ was diagnosed with a severe, frequently lethal metabolic condition that impairs critical bodily processes and lacks any standard cure. Survival into adulthood is rare for affected infants. In a bold move, specialists at Children's Hospital of Philadelphia (CHOP), collaborating with University of Pennsylvania researchers, engineered a custom CRISPR treatment exclusively for KJ. This therapy precisely targeted and repaired the specific genetic mutation causing his illness. Unlike traditional clinical trials or off-the-shelf drugs, it was uniquely developed and produced for him alone. The outcome has been transformative. After nearly ten months hospitalized, KJ went home in June. He marked his first birthday in August surrounded by family, rather than in intensive care. Today, he is achieving developmental milestones previously considered impossible: walking, thriving, and requiring far less intensive medical intervention. This holiday season, he will enjoy his first Christmas at home. KJ's remarkable progress is already influencing the future of medicine. Scientists are applying insights from his case to create tailored treatments for other young patients with uncommon inherited metabolic diseases. It also prompts vital discussions among regulators about approving therapies designed for just one individual.