Human samples
Human frozen postmortem tissues were obtained from the Mayo Clinic Brain Bank (Jacksonville, FL USA). Notably, 3 of the 12 control brains were obtained via the Einstein Aging Study. All brains were acquired with informed consent, and procedures were conducted according to the approved Institutional Review Board protocol (IRB# 15.009452). Data analysis was conducted as exempt human research, considering that these were postmortem brain samples, and they were not specifically collected for this study. The samples were dissected from the dorsolateral prefrontal cortex (Brodmann area 9; BA9; hereafter “frontal cortex”) and/or motor cortex (Brodmann area 4; BA4), which are of particular relevance for ALS and FTD pathological diagnosis, respectively. A total of 17 donors with C9-ALS (N = 6), C9-FTD (N = 5), or controls determined to have no remarkable pathology…
