Congenital nephrotic syndrome is a rare kidney disease which manifests in infants during the first 3 months of life, and is characterized by high levels of protein in the urine (proteinuria), low levels of protein in the blood, and swelling. This disease is primarily caused by genetic mutations which result in damage to components of the glomerular filtration barrier and allow for leakage of plasma proteins into the urinary space. Signs and symptoms
Urine protein loss leads to total body swelling (generalized edema) and abdominal distension in the first several weeks to months of life. Fluid retention may lead to cough (from pulmonary edema), ascites, and widened cranial sutures and fontanelles. High urine protein loss can lead to foamy appearance of urine. Infants may be born prematurely with low birth weight, and have meconium stained amniotic fluid or a large placenta. Complications
Frequent, severe infections: urinary loss of immunoglobulins
Malnutrition and poor growth
Blood clots (hypercoagulability): imbalance of plasma coagulation factors from urine protein loss
Hypothyroidism: urinary loss of thyroid-binding protein
Poor bone health associated with vitamin D deficiency: urinary loss of vitamin D binding protein
Acute kidney injury
Chronic kidney disease and ultimately end-stage kidney disease

Causes
Primary (genetic) causes
Mutations in the following five genes account for greater than 80% of the genetic causes of congenital nephrotic syndrome:
NPHS1 (Finnish Type): The gene NPHS1 encodes for the protein nephrin. This genetic variant is characterized by severe protein loss in the first several days to weeks of life.
Children who have a history of stroke from thrombotic complications can have neurologic delays.Undiagnosed cases are often fatal in the first year due to blood clots, infections or other complications. References
External links
OMIM: 256300 Congenital nephrotic syndrome, Finnish type; Congenital nephrotic syndrome 1 at NIHs Office of Rare Diseases
OMIM: 609049 Pierson syndrome; Microcoria and congenital nephrotic syndrome at NIHs Office of Rare Diseases