Etiology of musician's dystonia: familial or environmental?

To test the hypothesis that there is familial aggregation of dystonia and other movement disorders in relatives of patients with musician's dystonia (MD) and to identify possible environmental triggers.

The families of 28 index patients with MD (14 with a reported positive family history of focal task-specific dystonia [FTSD] and 14 with no known family history [FH-]) underwent a standardized telephone screening interview using a modified version of the Beth Israel Dystonia Screen. Videotaped neurologic examinations were performed on all participants who screened positive and consensus diagnoses established. All patients were investigated for DYT1 dystonia and suitable families were tested for linkage to DYT7. All family members were administered questionnaires covering potential triggers of FTSD.

A diagnosis of dystonia was established in all 28 index patients and in 19/97 examined relatives (MD: n = 8, other FTSD: n = 9, other dystonias: n = 2), 5 of whom were members of FH- families. In 27 of the 47 affected individuals, additional forms of dystonia were seen; other movement disorders were observed in 23 patients. In total, 18 families were multiplex families with two to four affected members. Autosomal dominant inheritance was compatible in at least 12 families. The GAG deletion in DYT1 was absent in all patients. Linkage to DYT7 could be excluded in 1 of the 11 informative families. With respect to potential environmental triggers, there was no significant difference between patients with MD/FTSD compared to unaffected family members.

Our results suggest a genetic contribution to musician's dystonia with phenotypic variability including focal task-specific dystonia.