DISEASE OF THE MONTH IgA Nephropathy: Recent Developments

IgA nephropathy (IgAN), a mesangial proliferative glomerulonephritis (GN), is the most common GN in all parts of the world where renal biopsy is widely practiced. It is unique among glomerular diseases in being defined by immunohistochemical findings, i.e., mesangial deposition of IgA, rather than by light microscopy. Because the clinical features of IgAN were discussed in 1997 (1), we focus on recent developments in IgAN. Henoch-Schönlein purpura (HSP) is an IgA-mediated systemic vasculitis in which the glomerular disease may be indistinguishable from IgAN. IgAN seems to be a kidney-restricted form of HSP. HSP is not discussed in detail here; the reader is referred to the recent review by Rai and colleagues (2).