MedlinePlus Health Topics
disease topic
Patient-friendly
Rare Diseases
Source: MedlinePlus Health Topics, U.S. National Library of Medicine
Last synced 8/6/2026Status: primary verified
A rare disease is one that affects fewer than 200,000 people in the United States. There are nearly 7,000 rare diseases. More than 25 million Americans have one. Rare diseases: May involve chronic illness, disability, and often premature death Often have no treatment or not very effective treatment Are frequently not diagnosed correctly Are often very complex Are often caused by changes in genes It can be hard to find a specialist who knows how to treat your rare disease. Disease advocacy groups, rare disease organizations, and genetics clinics may help you to find one. NIH: National Institutes of Health
Educational only
This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.