Question

Electron microscopy is diagnostic in:

• A. Goodpasture's syndrome
• B. Alport's syndrome
• C. Wegener's syndrome
• D. Churg-Strauss syndrome

Hint:

Look for the hereditary type IV collagen defect with a basket-weave GBM.

Answer 1

The Correct Option is B

Step 1: The question asks which renal disease is diagnosed mainly by the ultrastructural (electron microscopy) appearance of the glomerular basement membrane (GBM), rather than by light microscopy or immunofluorescence alone.
Step 2: Alport's syndrome is a hereditary nephritis caused by a mutation in the gene coding for the alpha-5 chain of type IV collagen. The defect produces a characteristic GBM change that is only visible on electron microscopy.
Step 3: On EM, the GBM in Alport's syndrome shows irregular thinning and thickening with splitting and lamellation of the lamina densa, giving a basket-weave appearance. This finding is essentially diagnostic of the disease.
Step 4: Why the others are wrong. Goodpasture's syndrome is diagnosed by linear immunofluorescence (anti-GBM antibody) and crescents on light microscopy, not by EM. Wegener's (granulomatosis with polyangiitis) and Churg-Strauss are ANCA-associated vasculitides diagnosed by serology, light microscopy (necrotizing granulomas, pauci-immune crescents) and clinical features.
Step 5: Therefore the disease in which EM is the diagnostic tool is Alport's syndrome.
Answer: Option B (Alport's syndrome).