BTN2A2 and rheumatoid arthritis: Especially, 20 genes including 11 ‘overlapped’ (ABCF1, FLOT1, HLA-F, IER3, TUBB, ZKSCAN4, BTN3A3, HSP90AB1, CUTA, BRD2, HLA-DMA), 5 ‘European-specific’ (PHTF1, RPS18, BAK1, TNFRSF14, SUOX) and 4 ‘Asian-specific’ (RNASET2, HFE, BTN2A2, MAPK13) genes were differentially expressed between RA patients and health controls in three studies or four studies (Table 1 and S4 Table), and these genes were regarded as ‘highly verified’ RA-associated genes.