Cervical dystonia in monozygotic twins: case report and review of the literature

We report on monozygotic male twins of German origin with early onset cervical dystonia. No other family members were affected. Although identical in age of onset and clinical course, there were phenotypic variations. While the second-born, more affected twin suffered from a symmetric retrocollis, the twin brother mainly presented with a spasmodic torticollis to the left. Dystonia remained focal in both siblings. A DYT1 gene deletion was excluded. Including our patients, hitherto only four twin pairs with idiopathic dystonia have been reported. Although dystonia in twins can be remarkably uniform in some cases, major differences in terms of disease progression, remissions, and disability may be found. These observations underline the role of inheritance in the pathogenesis of idiopathic dystonia but also indicate that some other factors contribute to the clinical presentation of dystonia.