Orphan Medicines for Pediatric Use: A Focus on the European Union.

Rare diseases are categorized as "orphan diseases" because their occurrence in a small number of patients means that, regardless of the apparent high unmet medical need, there is limited public and market interest to justify the high development risk and significant investment to develop new treatments. However, unexplored potential within the area, as well as a conducive regulatory environment, can further support the development of medicines to treat rare diseases, including for children.