CD79A and digestive system infectious disorder: A deeper understanding of the dysregulation of IgA from the perspectives of intestinal infections and gut microbiome should be of pivotal significance in understanding the pathogenesis of IgAN and diseases in which IgA is involved, such as IgA vasculitis, ankylosing spondylitis, Sjögren's syndrome, alcoholic liver cirrhosis, celiac disease, inflammatory bowel disease (IBD), and dermatitis herpetiformis.