This concentration-dependent phase separation has been reported for multiple LCR/PrLD-containing proteins, including ALS disease-causing proteins FUS, hnRNPA1, TIA1, and polyQ protein WHI312; because the polyQ tract is a predicted PrLD21,22, polyQ-ataxin-1 is expected to behave in this way in cells. Here, HNRNPA1 is linked to amyotrophic lateral sclerosis.