An orphan drug is a pharmaceutical product that is developed to diagnose, prevent or treat a rare disease afflicting a very small fraction of the population. A rare disease is defined as a medical condition affecting not more than 20,000 people in Korea, fewer than 200,000 people in the United States, not more than 50,000 in Japan, and not more than 5 in 10,000 people in the EU region. One of the prominent characteristics of these rare diseases is that some 80 percent of them, most of which are life-threatening or chronically debilitating, are of genetic origin. There are more than 6,000 rare diseases known today, with to the tune of 100 million affected by one or more of them in the OECD countries. ("Patients' Needs, Medicines Innovation and the Global Public Interests", 2014, UCL School of Pharmacy Drugs) As they are for a small number of patients with gravely serious medical conditions that have few, if any, alternative treatments, orphan drugs tend to be very expensive.
