C9orf72 and amyotrophic lateral sclerosis: Perturbed phase separation and membraneless organelle formation appears to explain one of the key pathological features of C9orf72-ALS/FTD, the nuclear depletion and cytoplasmic aggregation of TDP-43 present in 97% and 45% of ALS and FTD cases respectively (Ling et al., 2013).