However, NfL lacks disease specificity, as elevated levels are also observed with normal aging and across a range of neurodegenerative disorders, including multiple sclerosis (MS), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), multiple system atrophy (MSA), and Parkinson’s disease (PD). This evidence concerns the gene NEFL and multiple system atrophy.