IFNB1 and primary progressive multiple sclerosis: Exclusion criteria for study 2 [17] included neuromyelitis optica, PPMS, SPMS or progressive relapsing forms, relapse within 30 days, prior treatment with cyclophosphamide or mitoxantrone within 12 months, systemic corticosteroid therapy within 30 days, treatment with interferon beta, glatiramer acetate, natalizumab, plasmapheresis or intravenous immune globulin within 60 days or non-lymphocyte-depleting immunosuppressive therapies within 90 days.