GFAP and Parkinson disease: Evidence suggests that CSF and blood biomarkers closely reflecting the pathophysiology of Parkinson's disease, such as major intermediary filament of astrocytes glial fibrillary acidic protein (GFAP) (16), a marker of astroglial activation YKL-40 (17) and proinflammatory cytokines tumor necrosis factor-alpha, IL-6, and IL-12 (12), may have diagnostic and prognostic value.