Gene therapy has cured 19-month-old Teddi Shaw of metachromatic leukodystrophy, making her the first NHS patient treated for this rare, fatal nervous system disease. After a single infusion of Libmeldy at Royal Manchester Children’s Hospital, she’s now running around, chattering away, and showing no signs of the illness that typically kills children before age eight. The treatment works by correcting a faulty gene in the child’s own stem cells, eliminating the disease at its root rather than managing it. Her family’s joy is tempered by grief — Teddi’s older sister was diagnosed too late for the therapy to help, fueling calls for newborn screening. It’s a glimpse of medicine’s next era: one-time cures for inherited conditions, if access and early detection can keep pace.