Myoclonic dystonia

Myoclonic dystonia, also called myoclonus dystonia syndrome, is a rare movement disorder in which spontaneous muscle contractions cause abnormal posture. People with it show rapid, jerky movements of the upper limbs (myoclonus) together with distortion of body orientation from simultaneous activation of opposing muscles (dystonia). It results from loss-of-function mutations in the SGCE gene, which codes for epsilon sarcoglycan, a membrane protein found in neurons and muscle fibers. The disease is dominantly inherited, but because SGCE is imprinted and only the paternal copy is expressed, children usually fall ill only when the mutation comes from the father. There is no cure; ethanol often eases symptoms, which is why it is also called alcohol-responsive dystonia, and benzodiazepines such as clonazepam or deep brain stimulation are options.