C9orf72 and amyotrophic lateral sclerosis: This is in line with the findings of various other studies showing pre-symptomatic cortical hyperexcitability in FALS patients36, 37, 38 and wobbler mouse39, altered electrical properties in the spinal cord neurons of transgenic SOD1 G93A mice40, 41, 42, 43, 44 and the iPSC generated by ALS patients carrying SOD1, C9orf72 or FUS mutations45, and in zebrafish embryos transiently expressing mutant FUS34.