Abstract
Rare diseases are defined in the European Union as life-threatening or chronically disabling diseases with a prevalence not exceeding 50 cases per 100 000 inhabitants. European legislation started to regulate the issues of so called orphan drugs (OD, intended for treatment of rare diseases) in 2000.
Fifty percent of these diseases affect children and up to 80% have genetic basis. As for diagnoses involved, 40% of rare diseases are oncologic and 20% metabolic/gastrointestinal; hematological, respiratory, cardiovascular and nervous diseases represent 10% each.
Rare disease is typically a diagnosis without available effective treatment, often established late and not much known to both professional and lay public.