SUMO4 and amyotrophic lateral sclerosis: These results were confirmed on the protein level by Western blot analysis of lysates of skin biopsy-derived fibroblasts of patient TALS004-01, which were also shown to harbor the SUMO4:c.2T>C variant (Fig. 1c) and to contain significantly decreased unconjugated SUMO4 protein levels compared to fibroblasts of two sex- and age-matched non-ALS controls without rare SUMO4 variants (Fig. 1d, e).