Acknowledgements
We acknowledge EU Framework 7 (Euro-motor), JPND/MRC SOPHIA, STRENGTH and ALS-CarE project grants. JCK and JRH hold MNDA/MRC Lady Edith Wolfson Fellowships. We are grateful to patients and controls who donated biosamples for research.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.