TDP-43 and FUS variants affect multiple levels of gene and protein expression including DNA repair, RNA splicing, transport and translation that could contribute,36, 40, 41, 42, 43 but we observed transcription sites appearing only transiently, if at all, in motor neurons expressing ALS variants, pointing to the major impairment in HSPA1A induction being at the transcriptional level. This evidence concerns the gene TARDBP and amyotrophic lateral sclerosis.