CSF biomarkers can provide evidence for the presence of beta amyloid 1-42 (AB42) accumulation and downstream neuronal dementia in AD [tau and tau phosphorylated at threonine 181 (p-tau)], while isolated elevation of tau may also be seen in FTD and intermediate concentrations of CSF biomarkers often occur in DLB and VaD (Mattsson et al., 2012; Schoonenboom et al., 2012; Blennow et al., 2015; Ewers et al., 2015; Llorens et al., 2016). This evidence concerns the gene MAPT and Alzheimer disease.