Its physiological role is not completely understood but YKL-40 is elevated in the brain and cerebrospinal fluid (CSF) in several neurological and neurodegenerative diseases associated with inflammatory processes.
Expert opinion/commentary: CSF YKL-40 represents a pathophysiological biomarker reflecting immune/inflammatory mechanisms in neurodegenerative diseases, associated with tau protein pathology.
An increase in YKL-40 levels seems to correlate with disease severity and poor prognosis in many diseases, including several neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis, and Alzheimer's disease (AD).