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About orphan diseases



Orphan diseases are defined as conditions with a prevalence of less than 1 person in 2,000 in the European Union. Some are "ultra-rare," occurring in less than 1 in 50,000. These conditions are typically chronic in nature, often severely disabling or life-threatening. An estimated 6 to 8% of people suffer from an orphan disease. This would mean that 27 to 36 million Europeans suffer from an orphan disease.

An estimated 6,000 to 8,000 different types of orphan diseases exist. This vast diversity, coupled with the rarity of these diseases, means that only a limited number of healthcare providers can develop sufficient expertise to meet the specific needs of this patient population. Orphan diseases are often highly complex and affect multiple organ systems simultaneously. The pathogenesis is not known for all orphan diseases, and knowledge about the pathology itself, diagnosis, and possible treatment is not generalized. Instead, it is concentrated for each orphan disease among a few (or only one) expert(s), and in some cases, it is completely absent.

The low prevalence poses additional specific problems. Thorough scientific research is often hindered by the small patient groups, and for the development of appropriate treatments, the "return on investment" is also rather low, thus discouraging the development of new orphan drugs or other forms of therapy. Consequently, to date, appropriate treatment is available for only a small fraction of disorders with a molecularly known cause.


Source: Belgian Plan for Rare Diseases
December 2013

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