HTT and proteostasis deficiencies: The aggregated proteins include several proteins that are associated with neurodegenerative disease or other proteinopathies, such as huntingtin (HTT), TDP‐43, Gelsolin, Lysozyme, the heterogeneous nuclear ribonucleoproteins A2B1 (HNRNPA2B1), HNRNPA1, and in one of the LC‐MS/MS replicates, the valosin‐containing protein, VCP (Haltia et al, 1990; Pepys et al, 1993; DiFiglia et al, 1997; Hirabayashi et al, 2001; Watts et al, 2004; Neumann et al, 2006; Kimonis et al, 2008; Kim et al, 2013).