CD79A and proliferative glomerulonephritis: (1) Acute onset diffuse abdominal colicky pain (may include intussusception and gastrointestinal bleeding)(2) Histology showing leukocytoclastic vasculitis or proliferative glomerulonephritis with predominant IgA deposition.(3) Acute onset arthralgia or arthritis(4) Either proteinuria or haematuria