In an attempt to provide further insights into the alterations occurring during the neurodegenerative process in C9ALS/FTD skin fibroblasts, we characterize the oxidative stress, autophagy flux, SUMO2/3 protein levels as well as the mitochondrial function in skin fibroblast cultures from C9orf72 patients. Here, C9orf72 is linked to frontotemporal dementia.