Loss of FUS functionality is relevant to the pathogenesis of FTLD/ALS by demonstrating that formation of the FUS intranuclear complex with splicing factor, proline-, and glutamine-rich (SFPQ), an RNA-binding protein, in neurons is compromised by FTLD/ALS-associated mutations (Ishigaki et al., 2017). Here, SFPQ is linked to amyotrophic lateral sclerosis.