Narod SA. Tamoxifen ChemopreventionâEnd of the Road?. JAMA Oncol. 2015;1(8):1033â1034. doi:10.1001/jamaoncol.2015.2247. Download citation file:
About Rare Diseases. A rare disease is defined by the European Union as one that affects less than 5 in 10,000 of the general population. There are between 6,000 and 8,000 known rare diseases. Around five new rare diseases are described in medical literature each week.
There are more than 7000 diagnosed rare diseases and many more undiagnosed diseases. About 1 in 12 people (nearly three million Canadians) have a rare disease. Most known rare disorders are severe and chronic, with many being degenerative and life threatening.