1 Division of Neurology and the Mah Pooi Soo & Tan Chin Nam Centre for Parkinson's & Related Disorders, Department of Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
2 Department of Medicine, Hospital Sultanah Nur Zahirah, Kuala Terengganu, Malaysia.
3 Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
4 Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
5 Departments of Genetics and Genomic Sciences and Neurology, Mount Sinai School of Medicine, New York, NY, USA.
6 Department of Neurology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.