 IgM nephropathy, IgMN, is a rare form of kidney disease that affects people in both developed and developing countries. It is characterized by abnormally high levels of immune complexes in the bloodstream, which can lead to inflammation and damage to the kidneys. Symptoms may include nephritic syndrome, subnephrodic proteinuria, or hematuria. In some cases, IgMN can be treated with steroids, but many patients require additional treatment, such as rotexamab or stem cell transplantation. This article was authored by Aruna Vaniker.