Dystonia

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal movements and postures. Dystonias are clinically and genetically highly heterogeneous. Phenotypically, dystonias are classified as isolated, combined (in combination with another movement disorder), or complex dystonia (usually as one of several disease manifestations in a complex syndrome). It has recently been suggested to replace the original genetic classification (DYT1-DYT25) by a combined phenotype-gene term, such as DYT-TOR1A for DYT1 dystonia. While the (genetic) causes of most dystonias are still unknown, mutations in 16 genes have been identified to result in isolated or combined dystonia and more than 80 genes are known for complex dystonias. The proteins encoded by these genes have diverse cellular function including dopamine signaling, transcriptional regulation, transport in and within cells, or energy metabolism. Notably, a considerable number of dystonia genes have also been linked to other diseases, a phenomenon called pleiotropy.