IgA Nephropathy

IgA nephropathy (IgAN, Berger disease) is a chronic kidney disease caused by deposition of galactose-deficient IgA1 (Gd-IgA1) antibodies in the glomerular mesangium. The disease involves a multi-hit pathogenesis: elevated levels of abnormally glycosylated IgA1, formation of autoantibodies against Gd-IgA1, immune complex formation, and mesangial deposition triggering inflammation and glomerular injury. The clinical course is highly variable. Some patients have benign recurrent episodes of visible hematuria with preserved kidney function, while others develop progressive proteinuria, hypertension, and declining GFR leading to end-stage kidney disease. Risk factors for progression include persistent proteinuria above 1g/day, hypertension, reduced GFR at diagnosis, and certain histologic features on kidney biopsy (Oxford MEST-C classification). Treatment has historically focused on blood pressure control with RAAS blockade and immunosuppression in selected cases. The FDA recently approved targeted complement inhibitors and endothelin receptor antagonists specifically for IgAN, marking a new era of disease-specific therapy.