A child was diagnosed of having Finnish type of nephrotic syndrome. It is caused by defect in following protein:
**Core Concept**
Finnish type of nephrotic syndrome, also known as Congenital Nephrotic Syndrome of the Finnish type (CNF), is a rare genetic disorder characterized by massive proteinuria and renal failure in infants. It is caused by a mutation in a specific gene that encodes a crucial protein essential for the proper functioning of the kidney's filtration system.
**Why the Correct Answer is Right**
The correct answer is a defect in the NPHS1 gene, which encodes for the protein Nephrin. Nephrin is a transmembrane protein that plays a key role in maintaining the integrity of the glomerular filtration barrier in the kidneys. In CNF, mutations in the NPHS1 gene lead to the production of a truncated or dysfunctional Nephrin protein, resulting in the collapse of the glomerular filtration barrier and massive proteinuria.
**Why Each Wrong Option is Incorrect**
**Option A:** Podocin is another protein involved in the glomerular filtration barrier, but mutations in the NPHS2 gene, which encodes for Podocin, are associated with steroid-resistant nephrotic syndrome, not Finnish type of nephrotic syndrome.
**Option B:** Factor H is a protein involved in the complement system, but mutations in the CFH gene, which encodes for Factor H, are associated with atypical hemolytic uremic syndrome, not Finnish type of nephrotic syndrome.
**Option C:** Factor B is another protein involved in the complement system, but mutations in the CFB gene, which encodes for Factor B, are associated with atypical hemolytic uremic syndrome, not Finnish type of nephrotic syndrome.
**Clinical Pearl / High-Yield Fact**
Nephrin is a transmembrane protein that plays a critical role in maintaining the integrity of the glomerular filtration barrier. Mutations in the NPHS1 gene, which encodes for Nephrin, are a common cause of congenital nephrotic syndrome of the Finnish type.
**Correct Answer:** C. Factor B