Similarly, FTD patients, compared with other NDDs such as AD, showed higher CSF NfL levels [108], and NfL dosage helped to distinguish FTD from FTD phenocopies (subjects without signs of neurodegeneration, e.g., no frontotemporal atrophy in MRI, FDG-PET hypometabolism and stable serial clinical and neuropsychology assessment over time) [109]. This evidence concerns the gene NEFL and Alzheimer disease.