RESEARCH ARTICLE Clinical features and outco lo

Full list of author information is available at the end of the articleBackground Focal segmental glomerulosclerosis (FSGS) is one of the most common glomerular diseases leading to end-stage renal disease (ESRD); accounting for 20 to 25 % of adult patients undergoing kidney biopsy for evaluation of idio-pathic glomerulonephritis (GN) [1]. The estimated inci-dence of FSGS is 7 per 1 million in the United States [2] and 5.6 % of primary glomerular diseases in Korea [3]. A key pathological finding of FSGS on light microscopy is a segmental obliteration involving some portion of glom-erular capillaries by the extracellular matrix, but not all glomeruli [4,5]. On electron microscopy, diffuse efface-ment of foot-process without other abnormalities in the glomerular basement membrane is a prominent finding [5]. It is essentially considered a ‘podocytopathy’, which is asso-ciated with various insults directed to podocytes [6]; how-ever, the idiopathic form is most common. The underlying cause of FSGS is uncertain although circulating permeabil-ity factors may play a major role in its pathogenesis [7]