Here, we report a colony of humanized TLR7/TLR8 (hu TLR7/8) mice that developed a severe immune mediated phenotype prior to 6 months of age, although the phenotype was distinct from previous reports of SLE-like disease in Tlr7+/Yaa congenic mice [9], [12]. This evidence concerns the gene TLR8 and systemic lupus erythematosus.