The diagnostic potential of CSF NfL has been studied in several neurodegenerative disorders, including Alzheimer’s disease (AD) [49,50,51,52], amyotrophic lateral sclerosis (ALS) [53,54,55], multiple sclerosis (MS) [47], frontotemporal dementia (FTD) [56,57,58,59] and sporadic Creutzfeldt–Jakob disease (sCJD) [60,61]. Here, NEFL is linked to early-onset autosomal dominant Alzheimer disease.