Higher levels of serum or CSF NfL have been associated with MRI lesions, spinal cord and brain atrophy, gadolinium-enhancing lesions, increasing age, recent clinical relapses, clinical disability, and treatment efficacy in MS (Barro et al., 2018, Benkert et al., 2022, Brune et al., 2022, Disanto et al., 2017, Gunnarsson et al., 2011, Hakansson et al., 2017, Ineichen et al., 2021, Piehl et al., 2018, Preziosa et al., 2020, Tavazzi et al., 2020, Varhaug et al., 2018). Here, NEFL is linked to myeloid sarcoma.