Rapid-onset dystonia-parkinsonism: More than just dystonia

INTRODUCTION Rapid-onset dystonia-parkinsonism (RDP) is caused by mutations in a neuronspecific subunit of the sodium/potassium-transporting ATPase (Na, K-ATPase). As an inherited form of dystonia, it is also known as DYT12. Originally described in a large mid-Western family (1), RDP is now recognized worldwide as one of the rare causes of dystonia parkinsonism (2). The term RDP, coined by Dobyns et al. in the first description published in 1993, was meant to describe the syndrome of dystonia, bradykinesia, and postural instability. Despite the inclusion of some traits of parkinsonism, tremor at onset of symptoms is absent in RDP. Many of the patients with RDP report triggering events immediately prior to the abrupt onset over hours to weeks of severe dystonia. There is no treatment for RDP, but 20 years of study have expanded our understanding of the disease, pathophysiology, and the potential for the study of RDP to impact other areas of neuroscience.