CHI3L1 and frontotemporal dementia: YKL-40 showed higher values in FTD-ALS than in bvFTD (p = 0.033) and CBS (p = 0.016) (Fig. 4a), as well as in TDP with ALS in comparison with TDP without ALS (p = 0.004) and FTLD-TAU (p = 0.010) (Fig. 4b).