The disease is caused by a genetic disorder which results in a defect in a protein called Torsin A.[1] A mutation in the DYT1 gene causes the loss of an amino acid, glutamic acid, in the Torsin A protein. The defective protein creates a disruption in communication in neurons that control muscle movement and muscle control. This mutation is most usually inherited from a parent, but can occur sporadically.[2] The disease is caused by a dominant allele, meaning that the person affected needs only one copy of the mutated DYT1 gene to have symptoms.[3] However, only 30 to 40 percent of those that do have the gene actually have symptoms, leading researchers to believe that there are other factors involved.[4]