IgA nephropathy (IgAN) is a kidney disorder characterized by the buildup of immunoglobin A (IgA) in the glomeruli, which are bundles of capillaries that filter blood in the kidney. In advanced stages of the disease, the buildup of IgA in the glomeruli disrupts kidney functioning and, in approximately 30% to 40% of cases, leads to kidney failure. IgA is thought to form complexes with IgG, IgM, and C3 proteins in the blood and then accumulate in the glomeruli during filtration. However, the accepted explanation does not explain a unique hallmark of the disease: during the initial stages of IgAN, IgA deposition is seen in the mesangium, an area composed of mesangial cells and matrix within the glomerulus. In a study that was published in Science Advances on March 22, 2023, a group of researchers from Japan has uncovered the reason for IgA deposition being restricted to the mesangium. The researchers, including Professor Daisuke Kitamura from Tokyo University of Science and Dr. Yoshihito Nihei and Professor Yusuke Suzuki from Juntendo University, investigated the development of IgAN using specially bred mice, called gddY mice, which exhibit a disease similar to human IgAN. The open-access article is titled “Identification of IgA Autoantibodies Targeting Mesangial Cells Redefines the Pathogenesis of IgA Nephropathy.”