A STUDY OF IDIOPATHIC TORSION DYSTONIA IN A NON-JEWISH FAMILY - EVIDENCE FOR GENETIC-HETEROGENEITY

A gene (DYT1) for idiopathic torsion dystonia (ITD) was mapped to chro mosome 9q34 in non-Jewish and Jewish families; the dystonia in these f amilies usually began in childhood, with the limb muscles affected fir st. The role of the DYT1 gene in adult-onset and cervical- or cranial- onset ITD is unknown. We examined 53 individuals from four generations of a non-Jewish North American family with adult-onset ITD. There wer e seven affected family members, with a mean age at onset of 28.4 year s (range, 7 to 50 years). in six of the seven, the neck was affected f irst. All seven developed cervical dystonia, and dysarthria or dysphon ia occurred in five. Linkage data excluded the region containing the D YT1 locus, indicating that DYT1 was not responsible for ITD in this fa mily. This study provides evidence that a gene other than DYT1 is resp onsible for some cases of adult cervical-onset dystonia.