In total, the studies examining the association of the TNF-α G-308A polymorphism with IgAN included 1486 cases (with IgA nephropathy), and 1715 healthy controls, whereas the studies that examined only the association of the TNF-α G-308A polymorphism with progression of IgAN included overall 196 cases (progressors), and 526 controls (non-progressors). This evidence concerns the gene TNF and IgA glomerulonephritis.