A 22-year-old man evaluated for persistent microscopic hematuria has normal blood pressure, normal renal function, no deafness, and no ocular abnormality. His father has isolated hematuria. Electron microscopy shows diffuse uniform thinning of the glomerular basement membrane to approximately 180 nm with no splitting and no deposits. Immunofluorescence is negative. What is the most likely diagnosis?

• A Alport syndrome with early onset
• B Thin basement membrane lesion (benign familial hematuria) ✓
• C IgA nephropathy with minimal light microscopic change
• D C3 glomerulopathy with occult deposits

Explanation

Benign familial hematuria results from heterozygous COL4A3 or COL4A4 mutations, giving uniformly thinned GBMs with an autosomal dominant family history, preserved renal function, and no extrarenal features. In contrast, Alport syndrome is X linked or recessive with GBM splitting and basket weaving, progressive renal failure, sensorineural deafness, and ocular lesions, all absent here. Negative immunofluorescence excludes IgA nephropathy and C3 glomerulopathy.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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