Renal Pathology Practice Questions

Q: Most common mutation in Alport syndrome is in COL4A5, which is transmitted as?

X-linked. **Explanation:** Alport Syndrome is a hereditary nephritis caused by mutations in the genes encoding the **Type IV collagen** chains, which are essential components of the glomerular basement membrane (GBM), cochlea, and lens [1]. **1. Why X-linked is correct:** The most common form of Alport Syndrome (approximately **80% of cases**) is caused by a mutation in the **COL4A5** gene, located on the **X chromosome** [1]. This gene encodes the $\alpha$5 chain of Type IV collagen. Because it is X-linked, males are typically more severely affected, often progressing to end-stage renal disease (ESRD), while females are often carriers with milder symptoms (like isolated hematuria) [1]. **2. Why other options are incorrect:** * **Autosomal Recessive (Option B):** This accounts for about 15% of cases and involves mutations in **COL4A3 or COL4A4** (located on Chromosome 2). It presents with early-onset renal failure in both genders. * **Autosomal Dominant (Option A):** This is the rarest form (approx. 5%) and also involves mutations in **COL4A3 or COL4A4**, but follows a dominant inheritance pattern with slower progression. * **Variable (Option D):** While Alport syndrome is genetically heterogeneous, the specific question asks for the transmission of the **COL4A5** mutation, which is strictly X-linked. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Hereditary nephritis (hematuria/ESRD), Sensorineural deafness, and Ocular defects (e.g., **Anterior Lenticonus**). * **Electron Microscopy (Gold Standard):** Shows characteristic **"Basket-weave appearance"** due to irregular thickening, thinning, and splitting of the lamina densa. * **Immunofluorescence:** Shows a "negative" or "loss of expression" for $\alpha$3, $\alpha$4, and $\alpha$5 collagen chains in the GBM [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 929-930.

Q: Alport syndrome is due to defective-

Collagen. **Explanation:** **Alport Syndrome** is a hereditary nephropathy caused by mutations in the genes encoding the **Type IV collagen** chains (specifically α3, α4, or α5) [1]. Type IV collagen is a crucial structural component of the basement membranes in the glomerulus, the cochlea, and the lens of the eye. 1. **Why Collagen is Correct:** The defect leads to an abnormal glomerular basement membrane (GBM). Under electron microscopy, this manifests as a characteristic **"basket-weave" appearance** due to irregular thinning and thickening with longitudinal splitting of the lamina densa. 2. **Why other options are incorrect:** * **Elastin:** Defects in elastin are associated with conditions like Williams syndrome or cutis laxa, not Alport syndrome. * **Fibrillin:** Mutations in Fibrillin-1 lead to **Marfan Syndrome**, characterized by skeletal, ocular (ectopia lentis), and cardiovascular issues. * **Proteoglycan:** While proteoglycans are part of the extracellular matrix, they are not the primary structural defect in Alport syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Most commonly **X-linked Dominant** (COL4A5 mutation) [1]. * **Classic Triad:** 1. **Hereditary Nephritis:** Progressing to end-stage renal disease (ESRD) [1]. 2. **Sensorineural Hearing Loss:** Bilateral, high-frequency [1]. 3. **Ocular Defects:** Anterior lenticonus (pathognomonic) and maculopathy. * **Diagnosis:** Electron microscopy is the gold standard (Basket-weave appearance). Immunohistochemistry showing absence of α5 collagen staining in the GBM can also be helpful [1]. * **Note:** If the question asks for the specific collagen type, it is **Type IV** ("Can't see, can't pee, can't hear a high-C"). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 929-930.

Q: The gross specimen section of kidney depicts which of the following?

Polycystic kidney. ***Polycystic kidney*** - Shows **multiple cysts** of varying sizes throughout the renal parenchyma, causing significant **kidney enlargement**. - The cysts replace normal kidney tissue and give the characteristic **"bunch of grapes"** appearance on gross examination. *Renal cell carcinoma* - Presents as a **solid mass** with areas of **necrosis** and **hemorrhage**, not multiple cysts. - Typically shows a **golden-yellow color** with variegated appearance due to lipid content. *Medullary cystic kidney* - Features **small cysts** confined to the **corticomedullary junction**, with overall **kidney shrinkage**. - Results in **small, scarred kidneys** rather than the enlarged cystic appearance seen here. *Hydatid cyst* - Appears as a **single, large cyst** with **thick walls** and **daughter cysts** inside. - Caused by **Echinococcus granulosus** infection and typically involves the **liver** more commonly than kidneys.

Question 1

Most common mutation in Alport syndrome is in COL4A5, which is transmitted as?

Accepted Answer

X-linked

Answer

Autosomal dominant

Answer

Autosomal recessive

Answer

Variable, autosomal dominant or autosomal recessive

Question 2

Alport syndrome is due to defective-

Accepted Answer

Collagen

Answer

Elastin

Answer

Fibrillin

Answer

Proteoglycan

Question 3

Which of the following conditions is characterized by Type III Rapidly Progressive Glomerulonephritis (RPGN)?

Accepted Answer

Granulomatosis with polyangitis

Answer

Systemic Lupus Erythematosus (SLE)

Answer

IgA nephropathy

Answer

Cryoglobulinemia

Question 4

What is the most common lesion in diabetic nephropathy?

Accepted Answer

Diffuse glomerulosclerosis

Answer

Fibrin caps

Answer

Capsular drops

Answer

Kimmelstiel Wilson nodule

Question 5

A 37-year-old man develops pulmonary hemorrhage and glomerulonephritis. Lung biopsy with immunofluorescence demonstrates IgG deposition along the basement membrane. These antibodies are most likely directed against which of the following types of collagen?

Accepted Answer

Type IV

Answer

Type I

Answer

Type II

Answer

Type III

Question 6

Hemodialysis-associated amyloid is deposited in which of the following?

Accepted Answer

Knee joint

Answer

Tongue

Answer

Liver

Answer

Tongue

Question 7

Which of the following conditions is characterized by highly selective proteinuria?

Accepted Answer

Minimal change disease

Answer

Mesangial proliferative nephritis

Answer

Membranous glomerulonephritis

Answer

Focal glomerulosclerosis

Question 8

Immune complex-mediated glomerular damage is seen in all except?

Accepted Answer

Goodpasture's syndrome

Answer

Membranoproliferative GN

Answer

Crescentric GN

Answer

Focal segmental GN

Question 9

The gross specimen section of kidney depicts which of the following?

Accepted Answer

Polycystic kidney

Answer

Renal cell carcinoma

Answer

Medullary cystic kidney

Answer

Hydatid cyst

Question 10

Complement level is reduced in which of the following conditions?

Accepted Answer

Membranoproliferative glomerulonephritis

Answer

Minimal change disease

Answer

Membranous nephropathy

Answer

Focal and segmental glomerulosclerosis

Renal Pathology — MCQs

Renal Pathology — MCQs

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