C9orf72 and amyotrophic lateral sclerosis: If aberrant R-loop formation turns out to be a key pathogenic factor in C9orf72-related ALS/FTD, then ASO chemistries capable of preventing or otherwise abrogating such R-loop formation should be investigated for their therapeutic potential, as has been seen previously in myotonic dystrophy not only with LNA-gapmer but also with LNA-mixmer oligonucleotides [129].