The primary objective of this study is to evaluate the safety of nusinersen sodium injection in the postmarketing setting in China.The secondary objectives are to collect data on the efficacy and the pharmacokinetics of nusinersen sodium injection in the post-marketing setting in China.

Key Inclusion Criteria:

• Ability of the participant or his/her legally authorized representative (e.g., parent or legal guardian), as appropriate and applicable, to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information in accordance with national and local subject privacy regulations.
• The decision to newly prescribe nusinersen sodium injection according to the local marketing authorization, including documentation of 5q SMA diagnosis, has been made by the Investigator and agreed to by the participant (or legally authorized representative)

Key Exclusion Criteria:

• Hypersensitivity to the active substance or any of the excipients of nusinersen sodium injection.
• Current or past administration of nusinersen sodium injection, in either a commercial or a clinical study setting.
• Other unspecified reasons that, in the opinion of the Investigator or the Sponsor, make the participant unsuitable for enrollment.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Participants who are prescribed nusinersen sodium injection in China according to the local marketing authorization (including documentation of 5q SMA diagnosis), agree to the collection and use of data as specified in the protocol, and meet the eligibility criteria.

In accordance with Biogen's Clinical Trial Transparency and Data Sharing Policy on https://www.biogentrialtransparency.com/