BTN1A1 and ischemic stroke: Moreover, BTN2A1 is another protein in the butyrophilin protein family and it binds to CD209 on monocytes and dendritic cells, through which mediates internalization of various pathogens.[52] Genetic associations with plasma protein levels of BTN2A1 were colocalized with its gene expression levels in the heart left ventricles.[20] We found BTN2A1 and CD209 were on our validated list of causal candidate proteins for ischemic stroke (Figure 3), recapitulating the potential involvement of BTN‐mediated immune responses in pathogenesis of ischemic stroke.