C9orf72 and amyotrophic lateral sclerosis: These ALS-related miRNAs are highly enriched for a sequence motif (GDCGG; D = G, A, or U), and were previously found downregulated in serum samples of fALS patients with different genetic causes (FUS, SOD1, and C9orf72) of the disease [64], as well as in the majority (>60%) of sALS patients [65].