CSF analytes of total tau and beta-amyloid1-42 were obtained using previously reported procedures and evaluated with either a sandwich ELISA 2 (INNOTEST, Innogenetics, Ghent, Belgium) or a LUMINEX xMAP platform (INNO-BIA AlzBio3, Innogenetics). A ratio of total tau to beta-amyloid (t-tau:Aβ) was generated across platforms using an autopsy-validated conversion factor that has been cross-validated across two independent series (Irwin et al., 2012 (link)). Specifically, it has been demonstrated that a t-tau:Aβ ratio above threshold (>0.34) is 95.5% accurate across two autopsy series (Irwin et al., 2012 (link)). In this study cohort 11 patients had autopsy or a genetic mutation consistent with FTLD pathology and all of them were correctly classified with CSF as having FTLD pathology. Using this threshold we identified 72 patients with a CSF profile not consistent with AD, which we presume is FTLD, and 21 patients had a CSF profile consistent with AD. Our cohort that contains 22.5% AD cases provides a representative sample that is consistent with previous reports suggesting that approximately 20–30% of clinical FTD cases have AD pathology (Harris et al., 2013 (link); Lee et al., 2011 (link)).