Rare Disease vs Orphan Disease

• A rare disease, as defined by the Orphan Drug Act of 1983, is "a condition that affects fewer than 200,000 people." The European Union defines a rare disease as one that "affects fewer than 1 in 2,000 people."
• There is no difference between a rare disease and an orphan disease. The term orphan disease has been used to refer to rare disease in reference to the lack of drug companies willing to "adopt" them to develop treatments.
• The top five most common rare diseases are multiple sclerosis at 90 out of every 100,000 people, narcolepsy at 50 out of every 100,000 people, primary biliary cholangitis at 40 out of every 100,000 people, Fabry disease at 30 per 100,000 people, and cystic fibrosis at 25 per 100,000 people.

Key Insights

• Only a few types of rare diseases are tracked in the United States. These are usually infectious diseases, birth defects, and cancers. Since not all rare diseases are tracked, it is difficult to deterime the exact number of rare diseases and the number of people affected. However, it is estimated that there are around 25-30 million people in the United States living with some 7,000 rare diseases. Over 250 new conditions are reported every year in medical literature.
• Approximately 350 million suffer from a rare disease worldwide. Of these, around 50% are children.

Key Challenges

• Rare diseases are often misdiagnosed and take anywhere from 4 years to 8 years before being properly diagnosed. Rare diseases are scattered all over the world, resulting in fragmented knowledge of "causes of the disease, pathophysiology, natural course of the disease and epidemiological data."
• Due to the small number of people suffering from a rare disease it is often difficult or impossible to conduct clinical trials that adhere to the statuatory standards required to obtain drug or treatment approval.