1. Department of Public Health and Primary Care; Leiden University Medical Center; Leiden the Netherlands
2. Department of Neurology; Leiden University Medical Center; Leiden the Netherlands
3. Department of Neurology; Ulm University Hospital; Ulm Germany
4. Department of Epidemiology; Leiden University Medical Center; Leiden the Netherlands
5. Department of Neurodegenerative Disease; University College London Huntington's Disease Centre, University College London Institute of Neurology; London United Kingdom