In a recent study, levels of CSF YKL-40 were higher in frontotemporal lobar degeneration patients with tau pathology compared with Alzheimer’s disease patients, and the sAPPβ/YKL-40 ratio was sufficiently distinguished between the groups (AUC: 0.70, 95% CI: 0.61–0.79) [196]. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.