IgA nephropathy (IgAN) is the most common form of glomerulonephritis, a principal cause of ESRD worldwide, affecting up to 1.3% of the population. Kidneys of patients with IgA nephropathy show deposits of IgA-containing immune complexes with proliferation of the glomerular mesangium. Typical clinical features include onset before age 40 with hematuria and proteinuria, and episodes of gross hematuria following mucosal infections are common; 30% of patients develop progressive renal failure. [From OMIM]