1 Department of Molecular Neuroscience, University College London Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, Queen Square, London, UK; Department of Neurology, Oslo University Hospital, Oslo, Norway. Electronic address: lasse.pihlstrom@medisin.uio.no.
2 Department of Molecular Neuroscience, University College London Institute of Neurology, London, UK; National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.