Blackler et al. reported that the DR4tgLdlr−/− mice, mice generated by crossing HLA-DRB1*04:01 transgenic mice with Ldlr−/− (LDL knockout mice), showed comparable atherosclerosis levels to Ldlr−/− mice on a high-fat diet, despite their lower LDL levels (Blackler et al., 2023). Here, LDLR is linked to atherosclerosis.