Congenital nephrotic syndrome, Finnish type

Congenital nephrotic syndrome, Finnish type (CNF), also known as nephrosis 1 or congenital nephrotic syndrome type 1, is a severe inherited kidney disorder characterized by massive proteinuria (protein loss in the urine) that begins in utero and becomes clinically apparent at birth or within the first three months of life. It is caused by mutations in the NPHS1 gene, which encodes nephrin, a critical protein component of the glomerular filtration barrier in the kidneys. The disease was first described in Finland, where it occurs with notably higher frequency than in other populations. The hallmark features include heavy proteinuria, severe hypoalbuminemia (low blood albumin levels), generalized edema (swelling), and hyperlipidemia (elevated blood lipids). Affected infants typically present with a large placenta (greater than 25% of birth weight), premature birth, and rapidly progressive edema. The massive protein loss leads to susceptibility to infections, thrombotic complications, and failure to thrive. Elevated maternal serum and amniotic fluid alpha-fetoprotein levels during pregnancy can serve as prenatal indicators of the condition. There is no curative medical therapy for CNF. Management focuses on supportive care including intravenous albumin infusions, nutritional supplementation, anticoagulation therapy, infection prophylaxis, and treatment with ACE inhibitors or indomethacin to reduce proteinuria. Unilateral or bilateral nephrectomy may be performed to control protein loss, followed by dialysis. Kidney transplantation is the definitive treatment and is typically performed when the child reaches an adequate size, usually around 1–2 years of age. Without transplantation, the disease is fatal in early childhood. Recurrence of nephrotic syndrome after transplantation is uncommon but can occur in patients who develop anti-nephrin antibodies.

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