NON-DYT1 DYSTONIA IN A LARGE ITALIAN FAMILY

A large non-Jewish Italian family affected by idiopathic torsion dysto nia with autosomal dominant transmission and almost complete penetranc e is reported. The prevalent phenotype was characterised by early onse t with cranial-cervical involvement and progression to a segmental dis tribution; progression to generalisation was also found. Among 45 peop le examined, 14 were considered definitely or probably affected by idi opathic torsion dystonia. Eight definitely affected members had mean a ge (SD) at onset of 15.6 (12.5); idiopathic torsion dystonia started i n the cranial-cervical region in six of them, in the upper limbs in tw o; in four cases dystonia progressed to other body regions, in two cas es a generalisation was seen. Linkage analysis with 9q34 markers exclu ded the region containing the DYT1 locus in this family; linkage to th e 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.