Following the successful development and US FDA approval of nusinersen, an antisense oligonucleotide for the treatment of spinal muscular atrophy (105), tofersen, an antisense oligonucleotide targeting SOD1gene product, was developed by Ionis/Biogen and tested in a phase III trial on 108 participants with SOD1-ALS (106). Here, SOD1 is linked to proximal spinal muscular atrophy.