The GAG deletion in Tor1A (DYT1) is a rare cause of complex musician's dystonia.

Focal dystonia is the most common form of primary dystonia characterized by involuntary twisting, abnormal postures and repetitive movements in a specific body part. Musician’s dystonia (MD) is a type of focal task-specific dystonia that presents with loss of voluntary motor control of extensively trained movements when a musician is playing his instrument. The pathophysiology of focal dystonia remains largely unknown, however, we have recently reported an aggregation of different types of movement disorders in the families of MD patients suggesting a genetic contribution to the disease [1]. To date, seven genes have been mapped for hereditary primary dystonia, however only two of these genes have been identified [2]: The three-base pair GAG deletion in the Tor1A gene (DYT1) typically causes early, limb-onset, generalized dystonia. While this mutation has also been identified in rare focal dystonia cases [2], it was previously excluded in a small group of MD patients [3]. Likewise, mutations in the recently identified THAP1 gene (DYT6) cause early-onset generalized or segmental dystonia but have also been found in rare focal dystonia patients [2]. We have recently screened a large series of MD patients for THAP1 mutations and identified one variant of unknown pathogenicity in the 50untranslated region [4]. To further elucidate the role of Tor1A in MD, we here screened a large number of patients for mutations.