Talking About Rare Diseases

Originally, rare diseases and orphan diseases were not synonyms. Rare diseases became known as orphan diseases because pharmaceutical companies were not interested in developing treatments for them. The Orphan Drug Act (USA) used financial incentives for orphan drug development. Herewith, a definition for rare disease was also established. This differs slightly across countries. Some rare diseases respond to drugs that are not orphan drugs. Orphan diseases refer to neglected diseases and even common disorders as endometrial cancer and infantile diabetes. Nonetheless, nowadays very often rare and orphan are used as synonyms. The causes for rare diseases are very diverse. The majority are thought to be genetic. Most lack proper diagnosis, treatment, or known therapeutic targets. However, rare disease patients account for a huge proportion of the health burden. This chapter discusses rare (and orphan) diseases, what has been reported about them, and how they appear to the general public. The different categories of rare diseases are introduced.