IgA nephropathy.

Immunoglobulin A nephropathy results from the abnormal deposition of IgA immunoglobulin in the glomerulus, which leads to the characteristic presentation of painless hematuria. It is the most common glomerulonephritis worldwide. Originally described 30 years ago, it was thought to follow a benign course. We now know that IgA nephropathy leads to progressive renal destruction in about one third of affected patients. Alteration in glycosylation of circulating IgA may be an important pathophysiologic mechanism that predisposes to IgA deposition, although how this leads to parenchymal damage remains unclear. Hypertension, high-grade proteinuria, and elevated serum creatinine levels are known risk factors for progressive renal destruction. In addition to these well-recognized risk factors, there appear to be genetic variants, particularly within the angiotensin-converting enzyme gene, that portend a worse outcome.