Mutations of NPHS1, NPHS2, or WT1 may be responsible for severe forms of nephrotic syndrome in children, progressing to end-stage renal failure. Recent studies have shown that congenital nephrotic syndrome may be secondary to mutations of one of these three genes and that some patients have a digenic inheritance of NPHS1 and NPHS2 mutations. The clinical spectrum of NPHS2 mutations has broadened, with the demonstration that mutations in the respective gene podocin may be responsible for nephrotic syndrome occurring at birth, in childhood, or in adulthood. It is now well recognized that podocin mutations are found in 10%-30% of sporadic cases of steroid-resistant nephrotic syndrome with focal segmental glomerulosclerosis. Data from large cohorts indicate that the risk of recurrence of nephrotic syndrome after renal transplantation in patients with podocin mutations is very low.