Young adults with childhood-onset rare diseases fall into a care void when they age out of pediatric specialists who understand their condition

A child with a rare metabolic disorder, skeletal dysplasia, or inherited neuromuscular condition typically receives care at a specialized pediatric center where the team has seen dozens of similar cases. The geneticist, metabolic dietitian, physical therapist, and social worker all know the disease. Then the patient turns 18 (or 21, depending on the institution), and they're discharged to adult medicine -- where their new internist has never heard of their condition, has no treatment protocol, and has no idea which specialists to refer to. A 2025 position paper in the Orphanet Journal of Rare Diseases documented 21 prioritized issues in this transition, concluding that "while they often received specialized pediatric care, the adult healthcare system provides few resources for those whose rare disease began in childhood, and many adult care providers are hesitant to take on adults with rare disease." The clinical consequences are measurable. A study of 183 sickle cell disease patients at St. Jude found that those with more than six months between their last pediatric and first adult appointment had significantly more emergency department and inpatient visits and fewer outpatient visits than those who transitioned within six months. That gap -- the months or years where a patient has no specialist following them -- is where complications go undetected, medications get discontinued, and preventive care lapses. For rare disease patients whose conditions require ongoing monitoring to prevent crises (metabolic decompensation, cardiac events, respiratory failure), losing specialist oversight isn't an inconvenience. It's a medical emergency waiting to happen. The structural cause is that adult medicine is organized around common conditions: cardiology, oncology, endocrinology. There is no "adult rare disease" specialty. Pediatric geneticists and metabolic specialists don't have adult counterparts in most health systems. The National Survey of Children's Health found that only 18.4% of adolescents with special healthcare needs received any transitional support in 2019. Building transition programs requires funding, cross-departmental coordination, and institutional willingness to create clinics for patient populations too small to generate revenue. Most hospitals won't do it because rare disease patients are, by definition, rare -- there aren't enough of them to justify a dedicated adult transition program under fee-for-service economics.