**2.1 Inborn nephrotic syndrome**

Congenital nephrotic syndrome is the type of nephrotic syndrome which occurs in first 3 months of life and is due to genetic causes mostly by alterations in the gene encrypting nephrin, a podocyte opening diaphragm protein. For the first time, these mutations were expressed in the Finnish, from then the name congenital nephrotic syndrome of the Finnish type (CNF) [1]. Though the incidence of CNF is high in Finland it also occurs in other populations also. Congenital nephrotic syndrome is not either equivalent with CNF, reason is that alterations in other genes encrypting podocyte opening diaphragm proteins, early-onset nephrotic syndrome can also be caused by proteins such as podocin. Upto 40% of all cases of nephrotic syndrome occurring in the first 3 months of life are due to alterations in a sequence of podocin gene [2] in the earliest 3 months of life. Nephrotic syndrome may also be part of multisystemic syndromes such as nail-patella syndrome, Pierson syndrome, Denys-Drash syndrome, and others or a sequence of congenital infections such as cytomegalovirus and syphilis (**Table 1**).


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**Table 2.**

*Causes and Pathophysiology of Nephrotic Syndrome in Childhood*

IgM nephropathy

(DMS)

dominant FSGS

Penicillamine ACEIs Pamidronate Gold Lithium Mercury Interferon Heroin

Mitochondrial cytopathies Glycogen storage disease Fabry's disease

Obesity (usually with FSGS) Bee stings (MCNS) Pregnancy Oligomeganephronia

Membranous nephropathy (MN)

results Autosomal dominant FSGS

Above the infancy and above the first year of life, maximum of the nephrotic syndrome cases are idiopathic. MCNS (Minimal-Change Nephrotic Syndrome) is the most usual deviation, and is responsible for more than 80% of all cases [3]. Focal segmental glomerulosclerosis (FSGS), Membranoproliferative glomerulonephritis (MPGN), and mesangial multiply glomerulonephritis are the other less common histopathologic types in this age group (**Table 2**). For a few cases in this age group genetic disease is also responsible. 10–25% of all cases of familial and sporadic SRNS were caused by

> Membranoproliferative glomerulonephritis (MPGN) Minimal change nephrotic syndrome (MCNS) Focal segmental glomerulosclerosis (FSGS) Mesangial proliferative glomerulonephritis

Hereditary Mutation in *WT1* gene results autosomal dominant diffuse mesangial Sclerosis

Mutation in gene encoding transient receptor potential cation channel 6 *(TRPC6)*

Mutation in gene encoding CD2-associated protein *(CD2AP)* results autosomal

Mutation in gene encoding *α-actinin 4* leads to autosomal dominant FSGS Mutation in podocin*(NPHS2)* gene results autosomal recessive FSGS

Lymphoma (Hodgkin's most likely can lead to minimal change)

*DOI: http://dx.doi.org/10.5772/intechopen.86825*

**2.2 Nephrotic syndrome after infancy**

Idiopathic C1q nephropathy

Drugs NSAIDs

Metabolic diseases Glutaric acidemia

Blood and oncologic

Infections HIV

Others Food allergies

diseases

General diseases Systemic lupus erythematosus Sarcoidosis Diabetes mellitus Henoch-Schönlein purpura

> Leukemia Sickle cell disease

> Malaria Filariasis Schistosomiasis Hepatitis B and C

*Causative factors of nephrotic syndrome above 3 months of life.*

## **Table 1.**

*Causative factors of congenital nephrotic syndrome (CNS) in 0–3 months of age.*
