A newborn boy presents with edema and heavy proteinuria within the first week of life. The placenta weighs more than 25% of his birth weight. Both parents are healthy and of Finnish descent. Renal biopsy later shows microcystic dilatation of proximal tubules and diffuse foot process effacement without immune deposits. The defective protein is:

• A Nephrin ✓
• B Alpha actinin 4
• C Podocin
• D Type IV collagen alpha 5 chain

Explanation

Congenital nephrotic syndrome of the Finnish type results from homozygous or compound heterozygous NPHS1 mutations encoding nephrin, a slit diaphragm protein. It presents with proteinuria in utero, massive edema at birth, a large placenta, and a characteristic microcystic tubular pattern on biopsy. Podocin (NPHS2) mutations cause steroid-resistant nephrotic syndrome presenting in childhood, typically after the first year, while TRPC6 and alpha actinin 4 cause adult onset autosomal dominant FSGS.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.