Rare Diseases You've Never Heard Of

Characteristics of Rare Diseases

There are over 6,000 unique conditions classified as rare diseases. Many of these conditions have a great variety of symptoms that may vary between individuals. Around 80 percent of rare diseases have an identified genetic origin, while others may be the result of environmental causes or bacterial and viral infections.

Reviewed by: 
Review Date: 
February 28, 2014

Last Updated:
July 1, 2014