CCL2 and Alzheimer disease: None of these chemokine genes associated with AD in our Han Chinese population could be validated in the ADSP dataset [44], although we found that four genes (CCL2, CCR6, CXCL6, CX3CR1) were associated with AD at the gene-burden level under correction for different covariates, including the principal components, sequencing center, sex, age, and APOE ε4 and ε2 dosages, with the SKAT-O analysis [63] by using the ADSP dataset [44] (Additional file 1: Table S3).