Accepted for Publication: August 16, 2013.
Published Online: January 6, 2014. doi:10.1001/jamaneurol.2013.4808.
Conflict of Interest Disclosures: Dr Tassone has been a consultant for Novartis and Genentech. No other disclosures were reported.
Funding/Support: This work was supported by grant HD02274 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Role of the Sponsor: The funding organization had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Information: This work is dedicated to the memory of Matteo.
Additional Contributions: Randi J. Hagerman, MD, provided helpful comments.