Table 1 Etiologic classification of FSGS

Primary (idiopathic) FSGS

Secondary FSGS

1. Genetic mutations

  NPHS1

  NPHS2

  CD2AP

  TRPC6

  ACTN4

  INF2

  ANLN

  ARHGAP24

  ARHGDIA

  WT-1

  LMX1B

  LAMB2

  PAX2

  COQ2, COQ6, PDSS2, ADCK4

2. Virus associated

 HIV

 Parvovirus B19

3. Medication

 Heroin

 Interferon-α

 Lithium

 Pamidronate/alendronate

 Anabolic steroids

4. Adaptive structural-functional responses e.g., glomerular hypertrophy or hyperfiltration

4.1 Reduced kidney mass

 Oligomeganephronia

 Unilateral kidney agenesis

 Kidney dysplasia

 Reflux nephropathy

 Surgical kidney ablation

 Chronic allograft nephropathy

 Any advanced kidney disease with reduction in functioning nephrons

4.2 Initially normal kidney mass

 Diabetes mellitus

 Hypertension

 Obesity

 Cyanotic congenital heart disease

 Sickle cell anemia

5. Malignancy (lymphoma)

6. Nonspecific pattern of FSGS caused by kidney scarring

Focal proliferative glomerulonephritis (IgA nephropathy, lupus nephritis, pauci-immune focal necrotizing and crescentic glomerulonephritis)

Hereditary nephritis (Alport syndrome)

Membranous glomerulopathy

Thrombotic microangiopathy