Footnotes

• Contributors BW and CDW: major role in the acquisition of data; wrote the manuscript. RG and AH: designed and conceptualised the project; interpreted the data; revised the manuscript for intellectual content. ACL: interpreted the data; revised the manuscript for intellectual content. MO: designed and conceptualised the project; analysed and interpreted the data; revised the manuscript for intellectual content. BW submitted the manuscript.

• Funding The work was supported in part by grants from the German Federal Ministry of Education and Research (project FTLDc 01GI1007A, MND-Net 01GI0704), PreFrontAls (01ED1512), The ALS Association, the Thierry Latran Foundation and the Charcot Foundation for ALS Research.

• Competing interests BW has received honoraria from Biogen for a lecture. RG has received honoraria from Biogen as an advisory board member. ACL received financial research support from AB Science, Biogen Idec, Cytokinetics, GSK, Orion Pharma, Novartis, TauRx Therapeutics and Teva Pharmaceuticals. He also has received honoraria as a consultant from Mitsubishi, Orion Pharma, Novartis and Teva, and as an advisory board member of Biogen, Treeway and Hoffmann-La Roche. MO received honoraria as consultant for Biogen, Axon and Fujirebio. CDW has received honoraria from Biogen as an advisory board member and for lectures, and as a consultant from Hoffmann-La Roche.

• Patient consent for publication Not required.

• Provenance and peer review Not commissioned; externally peer reviewed.