Rare Disease Day: 21 Rare Diseases

February 28 is Rare Disease Day -- a day organized by EURODIS, the European Organisation for Rare Diseases, as well as like alliances across the globe. The idea? To raise awareness about rare diseases, which affect 30 million people in the U.S. alone.

So what is a rare or "orphan" disease really? According to the National Institute of Health (NIH), it's basically any disease that affects fewer than 200,000 people in the U.S. So some impact thousands; others, less than 10.

The problem is that the cause of many of these obscure diseases is unknown. Many are genetic; others are caused by environmental factors. According to the NIH, the majority have no treatments, though The Orphan Drug Act of 1983 provides incentives for drug companies to develop them. (The FDA has approved 340 such rare disease treatments thus far.)

What can you do to help? Educate yourself. Our list is just a tiny sample of all of the rare diseases out there. Once you've checked it out, help spread awareness, remembering this year's slogan -- "Rare But Equal."