In a study evaluating genetic carriers of the C9ORF72 mutation and manifesting an ALS or an FTD phenotype, ALS patients showed higher CSF levels of CHIT1 and neurofilament medium polypeptide (NEFM), and the ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1, an enzyme related to neuronal development) levels were upregulated in ALS patients, while neuronal pentraxin receptor (NPTXR, a protein operating as a trans-synaptic organizer) levels were downregulated in FTD [119]. Here, UCHL1 is linked to frontotemporal dementia.