In a prior feasibility study, these four proteins were associated with MS disease activity.50 Further, the three proteins (APLP1, CNTN2, GFAP) in addition to the best known NfL play roles in MS pathogenesis, including demyelination and remyelination,51,52 grey matter pathology,53 and T cell dysregulation.54,55 Given the complex pathogenesis of MS, our findings suggested that a serum multi-protein biomarker profile encompassing proteins involved in different MS pathogenesis pathways is superior to a single protein biomarker in informing real-world MS disability status. Here, NEFL is linked to myeloid sarcoma.