Indeed, several in vitro studies of purified ALS/FTD-linked mutant forms of TDP-43, FUS, hnRNPA1, and TIA-1 show that they exhibit aberrant phase separation, accelerate the formation of solid or gel-like structures and lead to thioflavin positive fibrillar aggregates (Molliex et al., 2015; Patel et al., 2015; Conicella et al., 2016; Mackenzie et al., 2017; McGurk et al., 2018). This evidence concerns the gene HNRNPA1 and amyotrophic lateral sclerosis.