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Rare diseases

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:

  • Amyotrophic lateral sclerosis (ALS), also called Lou Gehrig's disease. In ALS, the nerve cells that send messages to your voluntary muscles — the ones you can control, like in your arms and legs — die. At first, this causes mild muscle problems. You may have trouble walking, writing, or speaking. In time, you lose your strength and cannot move. When muscles in your chest fail, you cannot breathe.
  • Fabry disease. In Fabry disease, fat-like substances build up in the eyes, kidneys, and blood vessels. People with Fabry disease often survive into adulthood but are at increased risk of heart attack, stroke, and kidney failure.
  • Cervical dystonia. This is a painful condition in which your neck muscles contract (shorten) on their own, causing your head to twist or turn to one side.

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.

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Content last updated: September 22, 2009.

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