Mutation in NPHS1 gene causes which disease?
**Core Concept**
The NPHS1 gene encodes for the protein nephrin, which plays a crucial role in maintaining the integrity of the glomerular filtration barrier in the kidney. Mutations in this gene lead to a disruption in the normal functioning of the glomerulus, resulting in a specific kidney disease.
**Why the Correct Answer is Right**
The correct answer is Focal Segmental Glomerulosclerosis (FSGS), a disease characterized by scar tissue in the glomeruli, leading to proteinuria and renal failure. The mutation in NPHS1 impairs the nephrin protein's ability to maintain the charge barrier and size selectivity barrier, allowing proteins and albumin to leak into the urine. This results in the characteristic FSGS lesions on biopsy.
**Why Each Wrong Option is Incorrect**
**Option A:** Minimal Change Disease (MCD) - MCD is caused by mutations in the NPHS2 gene, not NPHS1. It's characterized by normal glomeruli on biopsy but massive proteinuria.
**Option B:** Membranous Nephropathy - This disease is caused by autoimmune reactions or infections, not mutations in the NPHS1 gene.
**Option C:** Alport Syndrome - This is a genetic disorder caused by mutations in the COL4A3, COL4A4, or COL4A5 genes, not NPHS1.
**Clinical Pearl / High-Yield Fact**
When evaluating a patient with nephrotic syndrome, it's essential to consider the underlying genetic cause, as this can guide treatment and prognosis. For example, FSGS due to NPHS1 mutations often requires aggressive treatment to prevent progression to end-stage renal disease.
**Correct Answer: C. Focal Segmental Glomerulosclerosis (FSGS)**