At the Children’s Hospital of Philadelphia (CHOP), a multidisciplinary team of doctors, clinicians, and researchers is advancing treatment for metachromatic leukodystrophy (MLD), a rare genetic disorder that affects growth and development in young children. As one of the country’s largest MLD programs, CHOP’s Leukodystrophy Center is leading efforts to standardize newborn screening guidelines nationwide to ensure more children are diagnosed and treated early, before they develop symptoms. After losing two children to this rare genetic disorder, a family from a small indigenous community in Alaska brought their newborn son, Nicholas, to CHOP when a newborn screening confirmed he had the same diagnosis. At CHOP, specialists were able to treat Nicholas using the first FDA-approved gene therapy for children with pre-symptomatic MLD. This therapy has the potential to slow or stop disease progression altogether, transforming the outlook for patients and families facing this rare disorder. Nicholas became CHOP’s youngest patient to receive stem cell gene therapy at only 6 months old, a milestone that represents a scientific breakthrough in medicine and hope for families affected by rare genetic diseases. Through CHOP’s breakthroughs in MLD treatment, more kids like Nicholas will receive life-saving medicine for this complex genetic disorder.