The global pharmaceutical industry is make huge investments in treatments for rare diseases, which once drew little interest from major drugmakers. 

A look at some key statistics on rare diseases:

- Patients with a rare disease in the U.S.: 30 million, nearly 1 in 10 people.

- Rare disease patients worldwide: 350 million, more than cancer and AIDS patients combined.

- Percentage of rare disease patients who are children: 50 percent.

- Threshold to be classified as a rare disease: fewer than 200,000 Americans affected.

- Number of known rare diseases: 7,000, with more discovered every year.

- Percentage of rare diseases caused by abnormal genes: 80 percent.

- Percentage of rare diseases with an FDA-approved treatment: 5 percent.

- Rare-disease drugs approved in the 1970s: fewer than 10.

- Rare-disease drugs approved since the 1983 Orphan Drug Act: 220.

- Rare-disease drugs approved in 2014: 17.

- New medicines in development for rare diseases: more than 450.

- U.S. venture capital funding of companies developing rare-disease drugs in 2003: $268 million. In 2013, $557 million.