For the forward MR analysis, PTSD was found to reduce the levels of CD62L− dendritic cell (DC) (beta = −0.254, FDR = 0.01), CD86+ myeloid DC (beta = −0.238, FDR = 0.014), CD62L− myeloid DC (beta = −0.26, FDR = 0.01), CD62L− CD86+ myeloid DC absolute count (beta = −0.264, FDR = 0.024), and CD62L− CD86+ myeloid DC (beta = −0.328, FDR = 0.002). Here, SELL is linked to post-traumatic stress disorder.