In mice models of SCD, unless HPX is present or replenished, heme causes endothelial cells to present surface adhesion molecules leading to stasis and vaso-occlusion in part via toll-like receptor-4 (TLR4) activation (Belcher et al., 2014) and pulmonary endothelia to produce neutrophil extracellular traps (Chen et al., 2014). The gene discussed is TLR4; the disease is Schnyder corneal dystrophy.