Inflammatory bowel diseases such as ulcerative colitis and Crohn’s disease are often combined with IgA nephropathy (11, 12).Besides, IgAN susceptibility loci can be divided into two categories according to the relationship with the intestinal disease (13, 14): the first category share with inflammatory disease (IBD)susceptibility loci such as HLA-DQ/DR, CARD9 and HORMAD2; the second involves genes encoding for the maintenance of intestinal immune barrier integrity and regulation of intestinal mucosal immune response such as DEFA, TNFSF13, VAV3, ITGAM-ITGAX and PSMB8. The gene discussed is CARD9; the disease is Crohn disease.