Podocytopathies

Abstract

Podocytes are the cells located on the outer (urinary) aspect of the glomerular capillary wall and are also known as visceral glomerular epithelial cells. Podocytopathies are diseases where the cell that is primarily injured/dysfunctional is the podocyte. The term is most literally applied to a group of genetically mediated conditions where a mutation in a podocyte-specific gene leads to a clinical phenotype including proteinuria. These relatively rare genetic conditions have been enormously important in helping us to understand podocyte biology, structure and function [reviewed in 1]. The knowledge thus acquired has accelerated our ability to study podocytes in other disease situations, including some of the most common forms of acquired kidney disease such as diabetic nephropathy. Minimal change nephropathy (MCN) and focal segmental glomerulosclerosis (FSGS) are the two forms of acquired glomerular disease that are most widely accepted to be podocytopathies: both are covered in separate chapters so that only the general concepts of podocytopathies illustrated by these diseases will be covered here. There is evidence of podocyte injury, plus good reasons for believing that the extent thereof is an important prognostic factor, in a variety of other renal diseases including diabetic nephropathy, membranous glomerulonephritis, IgA nephropathy and even renal transplant glomerulopathy, so that some degree of podocytopathy could be said to be a very widespread phenomenon. For the sake of brevity, I will focus on the issues raised by the genetic podocytopathies and by MCN and FSGS.