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.
Definition of RAREFACTION. 1. : the action or process of rarefying. 2. : the quality or state of being rarefied. 3. : a state or region of minimum pressure in a medium traversed by compressional waves (as sound waves). â rarÂ·eÂ·facÂ·tionÂ·al \-shnÉl, -shÉ-nÉl\ adjective. See rarefaction defined for kids. ADVERTISEMENT.