A Yorkshire family with adult-onset cranio-cervical primary torsion dystonia

Although a family history is described in approximately 20% of patients, large families with adult-onset craniocervical primary (idiopathic) torsion dystonia (PTD) are rare. We report a new British family with cranio-cervical dystonia. Seventeen members of the family were examined. Five cases were diagnosed as definite PTD and one as probable PTD. Mean age at onset was 29 years (range, 19-40 yrs). The phenotype was characterized by adult-onset cranio-cervical dystonia in all affected cases. A few cases had additional voice tremor and/or postural arm tremor. The GAG deletion in the DYT1 gene was excluded in the index case. Linkage analysis was performed between the disease and several marker loci spanning DYT6 and DYT7 regions, and haplotypes were reconstructed in all subjects. Although linkage analysis was not completely informative, reconstructed haplotypes excluded linkage between the disease and either DYT6 or DYT7. This report confirms that familial cranio-cervical dystonia is genetically heterogeneous, and further studies of other PTD families with similar clinical features are needed to identify other new genes.