BLK and systemic lupus erythematosus: Genes like CFH, HLA-DRA, HLA-DRB1, PXK, BLK, UBE2L3 and MTMR3 are shared loci between IgAN and SLE/LN based on GWAS, which highlights pathways including MHC class-II antigen presentation, complement regulation, signaling by the BCR, autophagy, and ubiquitin/proteasome-dependent degradation shared between these two complex diseases (18, 27, 31).