C9orf72 and amyotrophic lateral sclerosis: Although the precise pathophysiology of C9-ALS remains unclear, 1) loss of function of C9ORF72 protein,4 2) HRE of DNA/RNA-mediated toxicity,5,6 and 3) toxic repeat-associated non-ATG translation (RAN-T) products7,8 have been suggested as possible causes of neurotoxicity.