SMN2 and proximal spinal muscular atrophy: Nusinersen is a fully modified 2ʹ-MOE polysaccharide ASO that modifies the splicing of the SMN2 pre-mRNA.565 It promotes the production of functional full-length SMN protein throughout the spinal column and central nervous system (including motor neurons) by inducing the retention of exon 7 in SMN2. 566 A few clinical trials have demonstrated that the intrathecal administration of nusinersen to SMA patients is well tolerated and results in improved motor function.