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.
In the UK, a single rare disease may affect up to about 30,000 people. The vast majority of rare diseases will affect far fewer than this â some will affect only a handful, or even a single person in the whole of the UK. 80% of rare diseases have a genetic component. Often rare diseases are chronic and life-threatening.