NfL is a major structural protein only expressed in neurons and an indicator of axonal degeneration and injury used as a blood and CSF biomarker in the assessment of neurodegenerative diseases including frontotemporal lobal degeneration, amyotrophic lateral sclerosis, Alzheimer’s disease (AD), Multiple Sclerosis and primary tauopathies (15–17). The gene discussed is NEFL; the disease is Alzheimer disease.