From Genetics to Transcriptomics to Unravel the Mechanisms Behind a Poor Outcome in Multiple Sclerosis

Inclusion Criteria : Common criteria for retrospective MS patients: * Patients aged 18 years or older * Clinical isolated syndrome (CIS) with or without dissemination in space * Patients affiliated to an appropriate health insurance Criteria for Aggressive MS group • Start of a 2nd line therapy within the two years following the CIS Criteria for Non aggressive MS group * No conversion according to McDonald criteria from clinical isolated syndrome to multiple sclerosis within 2 years or * Conversion based to McDonald criteria treated or not with first line disease modifying therapy within 2 years. * Have a minimum of least 2 years of follow-up. Healthy volunteers * Aged 18 years or older * No history of clinically isolated syndrome or MS Pairing criteria : * Age +/- 5 years * Sex Prospective MS Patients * Patients aged 18 years or older * Clinical isolated syndrome (CIS) with or without dissemination in space * Patients affiliated to an appropriate health insurance Exclusion Criteria : * Ongoing participation to a another study * Refusal to genetic analyses * Immunosuppressive drug at the time of blood collection * Plasma exchange or corticosteroid treatment within the four weeks prior to blood sample * Adults under a legal protection regime (guardianship, trusteeship, judicial safeguard) * Pregnancy