A disease or disorder is defined as rare in Europe when it affects less than 1 in 2000. One rare disease may affect only a handful of patients in the EU, and another touch as many as 245,000.
There are between 6000 and 8000 rare diseases. On the whole, rare diseases may affect 30 million European Union citizens. 80% of rare diseases are of genetic origin, and are often chronic and life-threatening.