Conflict of interest statement: Competing Interests: JDB has served as a 
consultant to Biogen Idec and as a paid speaker for Oakstone Publishing. He 
receives research report from the Muscular Dystrophy Association and ALS Therapy 
Alliance. JMS has served as a consultant to Biogen Idec, Cytokinetics, Trophos, 
ISIS, Glaxo Smith Kline, and receives research support from the Muscular 
Dystrophy Association, ALS Association, ALS Therapy Alliance, Cytokinetics, 
Biogen Idec, Sanofi Aventis, Neuraltus. RC is employed at the National Institute 
of Neurological Disorders and Stroke. DS, over the last 24 months, has served as 
a biostatistical consultant to Averion, Inc, Gerson Lehrman Group, Guidepoint 
Global, Neuronova, Cytokinetics, Glaxo Smith Kline, Merck, Aggennix, Pfizer, 
Biogen Idec, and Elan. He has received research support from AstraZeneca, Roche, 
CytRx, and ISIS. MK has no relevant disclosures to report. DF has received 
research funds from Euroimmune, Allere, Focus, Biokit, BioRad and Diasorin, 
Chronic Fatigue Initiative. LK has no relevant disclosures to report. WSD has no 
relevant disclosures to report. FV has no relevant disclosures to report. AP 
receives revenue related to antibody patent licenses from Athena; owns stock in 
Johnson & Johnson; directs the Washington University Neuromuscular Clinical 
Laboratory which performs antibody testing; and receives research support from 
the National Institutes of Health, Muscular Dystrophy Association, Neuromuscular 
Research Fund, Insmed, Knopp, Cytokinetics, Biogen Idec, ISIS, Genzyme, GSK, 
Ultragenyx & Sanofi. JBC has no relevant disclosures to report. JK has no 
relevant disclosures to report. ES has no relevant disclosures to report. JR has 
served on scientific advisory boards and/or as a consultant for Hill-ROM Inc, 
Cytokinetics and Avanir Pharmaceuticals. RP has no relevant disclosures to 
report. JG receives research support from the Muscular Dystrophy Association and 
from the National Institute of Neurological Disorders and Stroke. KR has no 
relevant disclosures to report. JR has research funding from National Institutes 
of Health, Department of Defense, P2ALS, Muscular Dystrophy Association, Robert 
Packard Center for ALS Research at Johns Hopkins. He has acted as a consultant 
to Biogen Idec, Cytokinetics and Psyadon Pharmaceuticals, Inc. DJG has no 
relevant disclosures to report. MEC served on DSMB for Synapse and Trophos and 
was a consultant for TEVA, Millenium, GlaxoSmithKline and Biogen. This does not 
alter the authors' adherence to all the PLOS ONE policies on sharing data and 
materials.