Rare disease

A rare disease is a disease that affects a small percentage of the population. In some parts of the world, the term orphan disease describes a rare disease whose rarity results in little or no funding or research for treatments, without financial incentives from governments or other agencies. Orphan drugs are medications targeting orphan diseases.

Most rare diseases are genetic in origin and thus are present throughout the person's entire life, even if symptoms do not immediately appear. Many rare diseases appear early in life, and about 30% of children with rare diseases will die before reaching their fifth birthdays.^[1] With only four diagnosed patients in 27 years, ribose-5-phosphate isomerase deficiency is considered the 2nd rarest known genetic disease being beaten only by Fields Condition affecting two known individuals, Catherine and Kirstie Fields.^[2][3]

No single number has been agreed upon for which a disease is considered rare. Global Genes has estimated that currently approximately 10,000 rare diseases exist globally, with 80% of these having identified genetic origins.^[4]