RESUMO
IgA nephropathy [IgAN] is the most prevalent form of glomerulonephritis in countries where renal biopsy is widely practised. It is characterized clinically by the association of macroscopic haematuria and mucosal infection, and pathologically by the predominant deposition of IgA in the mesangium. The epidemiological and clinical aspects of the disease are considered and immunodysfunction summarized. The known abnormalities within the gastrointestinal lamina propria are discussed in the context of the mucosal plgA response and oral tolerance. Prognosis, and the lack of an effective treatment is outlined. Although there is overwhelming evidence of widespread abnormalities within the IgA immune systems in IgAN, our present techniques have not allowed us to pinpoint the origin of glomerular IgAN. However there is increasing evidence that abnormalities of mucosal immunity may result in an impaired ability to handle the normal environmental antigen load. This may play an important role in the pathogenesis of this common glomerulonephritis