Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis accounts for approximately 20% of cases of the nephrotic syndrome in children and 40% of such cases in adults, with an estimated incidence of 7 per 1 million.(1) It is the most common primary glomerular disorder causing end-stage renal disease in the United States, with a prevalence of 4%.(2) The cardinal feature is progressive glomerular scarring. Early in the disease course, glomerulosclerosis is both focal, involving a minority of glomeruli, and segmental, affecting a portion of the glomerular globe. With progression, more widespread and global glomerulosclerosis develops. Since the first clinical-pathological studies of the disease in the 1970s,(3) there has been renewed interest because of the increasing incidence of the disease,(4) better understanding of causation, and identification of the podocyte as the major cellular target.(5) The discovery that mutations in podocyte genes are associated with genetic focal segmental glomerulosclerosis has advanced the field of podocyte biology and stimulated new approaches to diagnosis and management.(6)