C9orf72 and frontotemporal dementia: UCHL1 was also elevated in CSF in comparisons of all other symptomatic groups with age matched non‐carrier controls (sporadic ALS log2fold change 0.53, FDR‐adjusted p‐value <0.001; C9orf72 ALS log2fold change 0.51, FDR‐adjusted p‐value <0.001; sporadic FTD log2fold change 0.41, FDR‐adjusted p‐value = 0.007; C9orf72 FTD log2fold change 0.31, FDR‐adjusted p‐value = 0.010) (Fig S2).