A Study of Multiple Doses of Nusinersen (ISIS 396443) Delivered to Infants With Genetically Diagnosed and Presymptomatic Spinal Muscular Atrophy

Key Inclusion Criteria:

1. Age ≤ 6 weeks at first dose.
2. Genetic documentation of 5q SMA homozygous gene deletion or mutation or compound heterozygous mutation.
3. Genetic documentation of 2 or 3 copies of survival motor neuron 2 (SMN2).
4. Ulnar compound muscle action potential (CMAP) ≥ 1 mV at Baseline.
5. Gestational age of 37 to 42 weeks for singleton births; gestational age of 34 to 42 weeks for twins.
6. Meet additional study related criteria.

Key Exclusion Criteria:

1. Hypoxemia (oxygen saturation <96% awake or asleep without any supplemental oxygen or respiratory support).
2. Any clinical signs or symptoms at Screening or immediately prior to the first dosing (Day 1) that are, in the opinion of the Investigator, strongly suggestive of SMA.
3. Clinically significant abnormalities in hematology or clinical chemistry parameters.
4. Treatment with an investigational drug given for the treatment of SMA biological agent, or device. Any history of gene therapy, prior antisense oligonucleotide (ASO) treatment, or cell transplantation.
5. Meet additional study related criteria.

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