FUS and amyotrophic lateral sclerosis: •High nuclear FUS expression was observed in fibroblasts in both controls and patients. Protein placement in mutant carriers was seen in both nucleus and cytoplasm (mostly cytoplasm).•Stress treatment caused the mis-localization of large amounts of FUS proteins in the cytoplasm and placement in the structure of SGs, instead time-dependent reduction was seen in all cases.•Fibroblasts mutant carriers had more SGs than ALS and control samples and persevere in the cell longer.