/Demographic and clinical characteristics for the cross-sectional and longitudinal cohorts are summarized in Tables 1 and 2 respectively. These included 105 ALS patients comprising 42 with fast disease progression (ALS-F; PRL > 1.0), 37 slow progressing cases (ALS-S; PRL < 0.5), 26 ALS patients carrying the C9orf72 hexanucleotide repeat expansion (C9+ve), 3 C9orf72-ve (C9-ve) patients found to have the ATX-2 gene expansion and 77 healthy controls (HC).