In the past few years, antisense oligonucleotides (ASO) have become a trendsetting class of marketed drugs. The best known ASO is nusinersen/Spinraza®, developed by Ionis and Biogen for spinal muscular atrophy (SMA). The same oligonucleotide sequence can be used for all patients with SMA. This is a life-changing drug, as infants with the most aggressive form of SMA have a projected life span of less than a year. Instead of being on a respirator, infants are thriving and meeting developmental milestones.