Diseases Beginning With Z
The purpose of the Rare Diseases and Related Terms list is to distribute information; although the list is updated regularly, it should not be used as a reference or guarantee that a condition is rare. The prevalence of a rare disease is usually an estimate and may change over time. A rare (or orphan) disease is generally considered to have a prevalence of fewer than 200,000 affected individuals in the United States.
* This symbol indicates that a condition is not rare but is one for which a question has been answered by the GARD Information Center.