Focal dystonia, the most common form of dystonia, is often task-specific and referred to as FTSD. Specific learned motor tasks, such as writing or playing a musical instrument, can trigger muscle spasms and interfere with performance while other actions are unaffected. FTSD has a frequency of 1 in 3,400 in the general population but increases to 1 in 200 among musicians (Pullman and Hristova, 2005). [from
OMIM]