Abstract
A large non-Jewish Italian family affected by idiopathic torsion dystonia with autosomal dominant transmission and almost complete penetrance is reported. The prevalent phenotype was characterised by early onset with cranial-cervical involvement and progression to a segmental distribution; progression to generalisation was also found. Among 45 people examined, 14 were considered definitely or probably affected by idiopathic torsion dystonia. Eight definitely affected members had mean age (SD) at onset of 15.6 (12.5); idiopathic torsion dystonia started in the cranial-cervical region in six of them, in the upper limbs in two; in four cases dystonia progressed to other body regions, in two cases a generalisation was seen. Linkage analysis with 9q34 markers excluded the region containing the DYT1 locus in this family; linkage to the dopa-responsive dystonia markers was also excluded. A comparison of the phenotype in the present family and other non-DYT1 families shows striking overlapping features differing from those of DYT1 idiopathic torsion dystonia.