We would like to extend our thanks to the individuals whose participation made this research possible. This work was supported financially by a Strategic Award from the Medical Research Council and Wellcome Trust (WT089698/Z/09/Z) and a grant from the Bachman-Strauss Dystonia Parkinsonism Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The work was undertaken at University College London Hospitals (UCLH) and University College London (UCL), which receive support from the funding streams of the Department of Health’s National Institute for Health Research Biomedical Research Centres. Expression data were provided by the UK Human Brain Expression Consortium (UKBEC), which comprises John A. Hardy, M.R., D.T., Michael Weale, Adaikalavan Ramasamy, Colin Smith, and Robert Walker. UKBEC members are affiliated with the UCL Institute of Neurology (J.A. Hardy, M.R., and D.T.), King’s College London (M. Weale and A. Ramasamy), and the University of Edinburgh (C. Smith and R. Walker).