Table 2.

Characteristic clinical and pathology features of the six forms of FSGS

Characteristic Features	Primary FSGS	Adaptive FSGS	APOL1 FSGS	Genetic FSGS	Infection/Inflammation Associated	Medication-Associated FSGS
Mechanism of Podocyte Injury	Circulating factor, possibly a cytokine	Mismatch between metabolic load and glomerular capacity	APOL1 variant–initiated inflammation	High-penetrance genetic variants (Mendelian or mitochondrial inheritance)	Postulated role of IFN and possible other cytokines	Presumed direct effect on podocytes
History	Acute onset of edema	Reduced renal mass: low birth weight, oligomeganephronia, ureteral reflux, morbid obesity; increased single-nephron GFR: cyanotic congenital heart disease, sickle cell anemia	Family history, may be unremarkable	Family history, may be unremarkable with recessive inheritance genes	HIV, CMV, possible: parvovirus B19, Still disease, natural killer cell leukemia	Bisphosphonate, lithium
Laboratory tests	Many have high-grade proteinuria and nephrotic syndrome	Any level of proteinuria, serum albumin may be normal	Any level of proteinuria	Any level of proteinuria	Any level of proteinuria	Any level of proteinuria
Renal pathology	Widespread foot process effacement	Large glomeruli, perihilar sclerosis variant most typical, partial foot process effacement	May resemble primary or adaptive forms	Variable	Variable	Variable
Treatment and response	May respond to IST	Responds well to RAAS antagonism, often with >50% proteinuria reduction	May respond to therapies used for primary and adaptive forms	High-penetrance genetic mutations: usually does not respond to IST	Treat the virus	Stop the medication
Recurrence after renal transplant	Possible	Unlikely	Possible	Unlikely	Possible if infection/inflammation persists	Unlikely

CMV, cytomegalovirus; IST, immunosuppressive therapy; RAAS, renin-angiotensin-aldosterone system; CG, collaspsing glomerulopathy. Modified from Kopp (24), with permission.