However, it is important to note that an elevation in NfL levels is common in other neurodegenerative diseases, including Alzheimer’s disease,81 Parkinson’s disease82 and multiple sclerosis,83 suggesting that NfL is a general marker of neurodegeneration induced axonal damage rather than specific to disease processes in frontotemporal dementia or amyotrophic lateral sclerosis. This evidence concerns the gene NEFL and neurodegenerative disease.