High NfL levels in serum and CSF have been detected in several neurodegenerative and neuroinflammatory disorders, including Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington disease, multiple sclerosis (MS) and meningitis, which correlated with the severity and progress of disease, brain and spine magnetic resonance pathological changes (especially atrophy), and “new” demyelinating lesions in MS [18,19,20,21,22,28]. The gene discussed is NEFL; the disease is Parkinson disease.