Designation for a group of rare diseases ("orphan"). In general, a disease is considered to belong to the group of orphan diseases if its incidence does not exceed 5/10,000 inhabitants/year. To date, more than 5000 such diseases have been identified. Rare disease status can be based on both epidemiological (< 5 patients in 10,000 people according to the EU definition) and economic criteria (no possibility to amortize development costs for disease-specific pharmaceuticals).
For rare diseases, there are generally no approved drugs available, so " off-label use" medication has to be resorted to. In very few cases are evidence-based guidelines available.
With a regulation for " orphan drugs" the legislator tries to solve this problem, which is especially important for dermatology.