Congenital Nephrotic Syndromes
Congenital and infantile nephrotic syndromes are those that manifest during the first year of life. They include diffuse mesangial sclerosis and Finnish-type nephrotic syndrome.
Nephrotic syndrome is more prevalent among children than adults.
Congenital and infantile nephrotic syndromes are generally rare inherited defects in glomerular filtration. Symptoms are centered around proteinuria, edema, and hypoproteinemia. These diseases are best diagnosed by their gene mutations, because their presentations and histopathologies are not sufficiently specific. Early, aggressive treatment may include ACE inhibitors, angiotensin receptor II blockers, and NSAIDs (eg, indomethacin) for proteinuria; diuretics, IV albumin, and fluid restriction for edema; and antibiotics, anticoagulation, and hypernutrition. Nephrectomy, followed by dialysis or kidney transplantation, may be necessary to stop the proteinuria.
This nephrotic syndrome is rare. Inheritance is variable. It is caused by a mutation in the PLCE1 gene, which codes for phospholipase C epsilon. Progression to end-stage renal failure occurs by age 2 or 3 yr.
Patients with severe proteinuria may require bilateral nephrectomy because of severe hypoalbuminemia; dialysis should be initiated early to ameliorate nutritional deficits and mitigate failure to thrive. The disorder usually recurs in a renal graft.
This syndrome is an autosomal recessive disorder that affects 1/8200 Finnish neonates and is caused by a mutation in the NPHS1 gene, which codes for a podocytic slit-diaphragm protein (nephrin).
Finnish-type nephrotic syndrome is rapidly progressive and usually necessitates dialysis within 1 yr. Most patients die within 1 yr, but a few have been supported nutritionally until renal failure occurs and then managed with dialysis or transplantation. However, the disorder may recur in a renal graft.
Several other rare congenital nephrotic syndromes are now genetically characterized. These disorders include
Corticosteroid-resistant nephrotic syndrome (defective NPHS2 gene coding for podocin),
Familial focal segmental glomerulosclerosis (defective ACTN 4 gene coding for alpha-actin 4),
Denys-Drash syndrome, which is characterized by diffuse mesangial sclerosis, male pseudohermaphroditism, and Wilms tumor (defective WT1 gene)