In addition, it is important to emphasize that the association signals elicited by the CHI3L1 variant for the mediation effect of PC3 on AD risk (i.e., rs7551263; Table 3) are not correlated (r2 = 0.04) with the lead CHI3L1 variants of the PC4 main effect (e.g., rs10399931; Table 2). This evidence concerns the gene CHI3L1 and Alzheimer disease.