Another SSO with a significant historyis nusinersen, a modified SSO which targets survival motor neuron1 and 2 (SMN1 and SMN2, respectively) pre-mRNA in patients with SMA.The severity of SMA is dependent primarily on the absence of SMN1and the absence of SMN2 to a lesser extent. The gene discussed is SMN2; the disease is proximal spinal muscular atrophy.