In particular, this regards to the glial fibrillary acidic protein (GFAP), which is a promising biomarker of disease progression, with the highest concentration in patients with marked neurological disability (Axelsson et al., 2011), and chitinase 3‐like 2, which is associated with long‐term disability progression in progressive MS patients (Comabella et al., 2021). The gene discussed is GFAP; the disease is myeloid sarcoma.