CCR9 and Alzheimer disease: Although we found five genes (CCL3, CCR7, CCR9, CCRL2, and XCR1) were nominally associated with AD in the combined Han Chinese sample in the gene-based burden test (Additional file 1: Table S2), none of the associations can be verified in the populations of European ancestry based on a data-mining of the ADSP dataset [44] (Additional file 1: Table S3).