A Study of the Safety of Nusinersen (Spinraza®) and Its Effects on Motor Function in Koreans Living With SMA Treated During Their Usual Medical Care

In this study, researchers will learn more about the effects of nusinersen, also known as Spinraza®, in Korean participants with spinal muscular atrophy, also known as SMA. This is a drug available for doctors to prescribe for people with SMA. This is known as an "observational" study, which collects health information about study participants without changing their medical care. In Korea, some medicines for rare diseases are allowed to be reviewed for up to 10 years when there are no other treatment options. This study was set up to support that review by collecting more information about nusinersen. In this study, researchers wanted to learn more about its safety and how it may help patients receiving it as part of their routine medical care in Korea. The main goal of the study is to learn about the long-term safety of nusinersen in Korean participants with SMA. The main question researchers want to answer are: • How many participants have adverse events and serious adverse events during the study? Researchers will also learn more about: * How does nusinersen affect the participants' muscle function and ability to move? * How long participants live after joining the study? * How many participants need help with their breathing during this study? This study will be done as follows: * Participants will join the study after signing an informed consent form, also known as an ICF. * During the study, health information from the participants' regular visits to their doctor will be collected about every 4 months. * During each visit, doctors will measure the participants' motor function with different tests. They will also check the participants' overall health and ask how they are feeling. * Each participant will be in the study for up to 2 years.

Key Inclusion Criteria: * Currently receiving or about to initiate treatment with commercial Spinraza in the postmarketing setting * Genetic documentation of 5q-linked SMA Key Exclusion Criteria: * Hypersensitivity to the active substance or any of the excipients of Spinraza * Ongoing participation or participation within 6 months or 5 half-lives of the agent (whichever is longer) of enrollment in other interventional clinical trials for the treatment of SMA * Inability to comply with study requirements NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.