In addition to the well-described “snowball” lesions of the corpus callosum on MRI [44] and elevated total protein in cerebrospinal fluid found in the majority (> 80%) of patients diagnosed Susac syndrome [45], preliminary findings suggest that elevated serum neurofilament light chain and serum glial fibrillary acidic protein could be useful biomarkers of disease activity and treatment efficacy [46, 47]. The gene discussed is GFAP; the disease is Susac syndrome.