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A rare disease is a condition that affects fewer than 200,000 people nationwide. Some of them affect fewer than 100 people. There are close to 7,000 rare diseases, many of which are caused by defective genes. Most rare diseases are fatal.
Some rare diseases include:
Getting a diagnosis for a rare disease can be frustrating and take a long time. If you have a rare disease, it can be difficult to find a specialist who knows about your disease. You might need to travel to see a specialist. If treatments exist, they often cost a lot because only a few people use them. Finding others who can relate to your experience can be hard. Online support groups can help people affected by rare diseases connect no matter where they live.
Altogether, rare diseases affect as many as 25 million Americans. Learning about rare diseases and finding treatments for them are an important public health concern.
Content last updated: September 22, 2009.