Elevated CHI3L1 expression has been observed in patients with acute brain pathologies such as traumatic brain injury (TBI) and cerebral ischemia [17, 22, 23], as well as in patients with CNS tumors such as gliomas [16, 24, 25], including neurodegenerative disorders such as Alzheimer’s disease (AD) [26], Parkinson’s disease (PD) [27], amyotrophic lateral sclerosis (ALS) [28], and Creutzfeldt-Jakob disease (CJD) [29, 30] and neuroinflammatory diseases such as multiple sclerosis (MS) [8], neuromyelitis optica (NMO) [31], and HIV-associated dementia (HAD) [32]. The gene discussed is CHI3L1; the disease is neuromyelitis optica.