FUS and amyotrophic lateral sclerosis: Lastly, we investigated the degree of UMN involvement in patients carrying mutations in the four major ALS-associated genes, namely c9orf72, SOD1, TARDBP and FUS. Interestingly, we observed that patients carrying the c9orf72 hexanucleotide repeat expansion had higher PUMNS values compared to individuals without the mutation (13 [0–28] vs. 9 [0–29]; p = 0.01), suggesting a phenotype characterized by UMN signs in this group.