BTN2A2 and megaloblastic anemia: Correlation analysis showed that the expression of CD200, SIPRA, CD276, PDCD1LG2, and TNFSF15 was found significantly correlated with IGS, respectively (Figure 2A, Figure S4A), while the expression of BTN2A2, BTN3A1, CD160, CD200, CD276, and CEACAM1 was found significantly correlated with BGS, respectively (Figure 2B, Figure S4B).