Accepted for Publication: July 3, 2013.
Published Online: October 14, 2013. doi:10.1001/jamaneurol.2013.4111.
Study concept and design: Manford, Taylor, Chinnery.
Acquisition of data: Spyropoulos, Manford, Alston, Yu-Wai-Man, He, Chinnery.
Analysis and interpretation of data: Spyropoulos, Manford, Horvath, Yu-Wai-Man, Taylor, Chinnery.
Drafting of the manuscript: Spyropoulos, Manford, Chinnery.
Critical revision of the manuscript for important intellectual content: Horvath, Alston, Yu-Wai-Man, He, Taylor, Chinnery.
Obtained funding: Chinnery.
Administrative, technical, or material support: Manford, Taylor, Chinnery.
Study supervision: Manford, Taylor, Chinnery.
Conflict of Interest Disclosures: None reported.
Funding/Support: The Wellcome Trust sponsored this study.
Role of the Sponsor: The Wellcome Trust had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We are grateful to Catherine Zhang for her help collecting some of the clinical data.