TARDBP and proteostasis deficiencies: To explore if dysregulated alternative splicing could play a role in the pathophysiology of TDP-43 proteinopathies, we measured inclusion levels of TDP-43-mediated alternative exons in IBM muscles (Fig. 9a, Supplementary Data 6) as well as in pathological brain regions of ALS and FTLD cases with reported TDP-43 pathology (ALS-TDP and FTLD-TDP) (Fig. 9b, c, Supplementary Data 6).