Glomerular diseases: genetic causes and future therapeutics.

The glomerulus consists of capillary tufts, a mesangial cell component and the Bowman capsule. The glomerular filtration barrier is composed of glomerular endothelial cells, a basement membrane, and podocytes. Particular components of the slit diaphragm and the glomerular basement membrane strictly orchestrate the integrity of the glomerular filtration barrier. The basement membrane is made of a highly crosslinked macromolecular meshwork of type IV collagen, proteoglycans, and laminin. Genetic forms of glomerular disease are predominantly caused by genetic defects in these molecular structures or in factors that regulate the glomerular filtration barrier. In addition, abnormal IgA1 glycosylation can increase susceptibility to IgA nephropathy. Dysregulation of the complement system or of platelet activation can lead to the development of endocapillary lesions, which manifest as thrombotic microangiopathy. Glomerular dysfunction is also encountered in several genetic metabolic and mitochondrial disorders. Discoveries of mutations in a range of genes have provided new insights into the mechanisms of glomerular disease. In this Review, we summarize recent progress in the genetics and therapeutics of a number of glomerular diseases.