Serum Neurofilament-light Chain and GFAP Levels in Patients From the OFSEP Cohort at Different Landmarks of Multiple Sclerosis

Inclusion Criteria:

• The patient has been correctly informed.

• The patient must have given their informed and signed consent.

• The patient must be insured or beneficiary of a health insurance plan.

• The patient is at least (≥)15 years old.

• The patient has MS according to diagnosis criteria (Thompson et al. 2017) and:

• Participates to the OFSEP-HD cohort (ancillary study);

• Has a Expanded Disability Status Scale score comprised between 0 - 7.0;

• With or without Disease Modifying Drug;

• For Work Package 3: patients enrolled in any OFSEP-HD centre that meet landmarkcriteria for an active MS (relapse, or Expanded Disability Status Scaleprogression, or active MRI) during follow-up;

• For Work Package 4: patients with a stable disease enrolled in OFSEP-HD studyin Nîmes or Nantes University Hospitals.

Exclusion Criteria:

• Within the past three months, the patient has participated in another interventionalstudy that may interfere with the results or conclusions of this study.

• The patient is in an exclusion period determined by a previous study.

• The patient is under judicial protection.

• The patient refuses to sign the consent.

• It is impossible to correctly inform the patient (inability to understand the study,language problem).

• The patient is pregnant or breast-feeding.

• The patient is under 15 years old.

• Inability to answer questionnaires.

• Clinically isolated syndrome (CIS) that does not meet the criteria of MS.

• Radiologically isolated syndrome (RIS).

• Patient with Neuromyelitis optica spectrum disorder.