Focal segmental glomerulosclerosis (FSGS) is not a single disease. Instead, it is a histopathological entity that is the manifestation of a wide range of clinical insults that injure the podocyte, a key structural element in the glomerular filtration barrier. The current classification of FSGS includes four subtypes – primary immune-mediated, genetic, secondary, and undetermined cause. Based on this scheme, patients are treated empirically with a combination of non-specific renoprotective drugs and immunosuppressive agents in an effort to reduce proteinuria and preserve kidney function.