Accepted for Publication: June 13, 2014.
Published Online: October 6, 2014. doi:10.1001/jamaneurol.2014.2082.
Study concept and design: Pulst.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Neuenschwander, Thai, Pulst.
Critical revision of the manuscript for important intellectual content: Figueroa, Pulst.
Statistical analysis: Neuenschwander, Thai.
Obtained funding: Pulst.
Administrative, technical, or material support: Figueroa.
Study supervision: Pulst.
Conflict of Interest Disclosures: Dr Pulst has received royalties from Cedars-Sinai Medical Center and is a consultant for Progenitor Lifesciences. No other disclosures were reported.
Funding/Support: This work was supported in part by grants RC4NS073009, R21NS079852, R21NS081182, and R01NS33123 from the National Institute of Health (Dr Pulst) and by the University of Utah’s ACCESS and Bioscience Undergraduate Research Programs.
Role of the Funder/Sponsor: The funders 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: After the manuscript was accepted for publication, Lattante et al described the contribution of ATXN2 intermediary polyglutamine expansions in a spectrum of neurodegenerative disorders (Lattante S, Millecamps S, Stevanin G, et al; French Research Network on FTD and FTD-ALS. Contribution of ATXN2 intermediary polyQ expansions in a spectrum of neurodegenerative disorders. Neurology. 2014;83:990-995).
Additional Contributions: We are grateful to the patients with ALS and their spouses. We thank the investigators who sent detailed data for use in the meta-analysis. They received no compensation for these contributions.
Correction: This article was corrected online December 8, 2014, for an error in reference 19.