|Rare diseases are defined as diseases with a prevalence of less than 1 person in 2,000 in the European Union. Some diseases are ‘ultra rare’, occurring les than 1 in 50,000. These diseases are typically chronic in nature, not infrequently severely disabling or life-threatening. An estimated 6-8% of people suffer from a rare disease. This would mean that 27 to 36 million Europeans suffer from a rare disease.
|An estimated 6,000 to 8,000 different types of rare diseases exist. This very high diversity and, in particular, the rare nature of the diseases mean that only a limited number of healthcare providers can develop sufficient expertise to meet the specific needs of this patient population. The diseases are often highly complex and affect multiple organ systems simultaneously. The pathogenesis is not known for all rare diseases, and knowledge about the pathology itself, diagnosis and possible treatment is not generalised and, for each rare disease, is concentrated among a few (or only 1) expert(s) and, in some cases, even absent altogether.
|The low prevalence poses additional specific problems. Thorough scientific research is often hampered by the often too small groups of patients and in addition, for the development of appropriate treatments, the return on investment is also quite low and therefore discourages the development of new (orphan) drugs or other forms of therapy. Thus, to date, appropriate treatment is available for only a small fraction of disorders with a molecularly known cause.
Source: Belgian Plan for Rare Diseases