Characterization of New Phenotypes of Patients With Spinal Muscular Atrophy Treated With SMN Restoring Therapy

Inclusion Criteria:

• Genetically confirmed infantile or juvenile spinal muscular atrophy

• Treated with a therapy that restores SMN protein expression (e.g. nusinersen,risdiplam, onasemnogene abeparvovec)

• Aged 0 to 15 years inclusive

• Informed consent signed by both parent(s)/legal guardian(s) and patient's assent

• Affiliated or beneficiary of a health insurance plan*. * for inclusion in France

Exclusion Criteria:

• Other condition likely to interfere significantly with ASI assessment and clearlyunrelated to the disease

• Other associated neurological disease

• Current pregnancy or breast-feeding (a pregnancy test will also be performed atinclusion).

Please note that patients with a specific contraindication to MRI (i.e. metallic foreign body, claustrophobia and other reasons determined by the investigators) will be allowed to participate in the study, but MRI will not be performed.