We found that levels of YKL-40 in DLB patients with a t-tau/Aβ1–42 ratio indicative of AD pathophysiology (>0.52) were higher than those with a normal t-tau/Aβ1–42 ratio (<0.52, Fig. 3a, p = 0.04). This evidence concerns the gene CHI3L1 and Alzheimer disease.