SUMO4 and amyotrophic lateral sclerosis: The latter assumption is corroborated by the fact that exposure to certain potentially pertinent oxidative stress-related factors, i.e., head trauma or tumor with and without treatment by radiation or chemotherapy, were significantly more frequent in patients carrying the SUMO4:c.2T>C variant compared to non-carriers in our ALS cohort (p = 0.012; Tables 2, 3).