Familial Mediterranean fever is a hereditary inflammatory disorder that affects groups of people originating from around the Mediterranean Sea (hence its name). It's prominently present in the Armenian people, Sephardi Jews (and, to a much lesser extent, Ashkenazi Jews), Greeks, and people from Turkey and the Arab countries.
The symptoms are generally self-limiting and will disappear of their own accord. Analgesics and anti-inflammatories can be used to treat the symptoms of attacks. However, FMF patients appear to be at risk for more serious disorders such as amyloidosis and vasculitis.
Familial Mediterranean fever at NIH