Last May, the case of baby KJ made headlines: the child, suffering from a severe metabolic disorder, received a therapy developed specifically for him in just six months. The rapid improvement in his condition and his discharge from the hospital left the rare disease community with a pressing question: was this an unrepeatable one-off, or a replicable model of intervention? The right answer might be the latter, as demonstrated by the launch of the Center for Pediatric CRISPR Cures in California. This new center, to be led by Fyodor Urnov, begins with the mission of developing customized genome-editing treatments for eight young patients with congenital metabolic and immune system disorders.