Renal Pathology — MCQs
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Which of the following is not a non-proliferative glomerulonephritis?
Pauci-immune glomerulonephritis is seen in which of the following conditions?
An 8-month-old male infant presents with progressive renal and hepatic failure. Despite intensive medical therapy, the infant dies. At the time of autopsy, the external surfaces of his kidneys are found to be smooth, but the cut section reveals numerous cysts that are lined up in a row. What is the mode of inheritance of this renal abnormality?
A 40-year-old hypertensive male was admitted to the hospital with sudden onset of headache and altered sensorium. On examination, his blood pressure was observed to be 220/110 mm Hg. The patient died four hours later. What is the likely pathological finding in his kidneys?
Mesangial deposits of Lambda chain are seen in which condition?
Which of the following is MOST relevant in renal vascular hypertension?
Which of the following is seen in nephrotic syndrome?
What is the commonest histological finding in hypertensive nephrosclerosis?
Which of the following is NOT a steroid-responsive glomerulonephritis?
Which of the following proteins is most commonly associated with steroid-resistant nephrotic syndrome?
Renal Pathology Indian Medical PG Practice Questions and MCQs
Question 121: Which of the following is not a non-proliferative glomerulonephritis?
- A. Membranous glomerulonephritis
- B. Mesangiocapillary glomerulonephritis (Correct Answer)
- C. Diabetic glomerulosclerosis
- D. Amyloidosis
Explanation: ### Explanation Glomerular diseases are broadly classified into **Proliferative** and **Non-proliferative** patterns based on light microscopy findings. This distinction is crucial for NEET-PG as it correlates with clinical presentation (Nephritic vs. Nephrotic syndrome). **Why Option B is Correct:** **Mesangiocapillary Glomerulonephritis (MCGN)**, also known as **Membranoproliferative Glomerulonephritis (MPGN)**, is a **proliferative** glomerulonephritis [1]. As the name suggests, it is characterized by the proliferation of mesangial cells and increased mesangial matrix, along with the interposition of mesangial cell processes into the capillary basement membrane, leading to the classic "tram-track" appearance [2]. It typically presents with a mixed nephritic-nephrotic picture. **Why Other Options are Incorrect:** * **A. Membranous Glomerulonephritis:** Despite the name, there is no cellular proliferation. It is characterized by diffuse thickening of the glomerular capillary wall due to subepithelial immune complex deposits ("Spike and Dome" appearance) [1]. * **C. Diabetic Glomerulosclerosis:** This is a metabolic/hemodynamic injury resulting in basement membrane thickening and nodular (Kimmelstiel-Wilson lesions) or diffuse mesangial matrix expansion, but **not** true cellular proliferation [1]. * **D. Amyloidosis:** This involves the extracellular deposition of fibrillar proteins. While it causes glomerular damage and massive proteinuria, it is a non-proliferative process [1]. **NEET-PG High-Yield Pearls:** * **Non-proliferative (Nephrotic):** Minimal Change Disease (MCD), Focal Segmental Glomerulosclerosis (FSGS), Membranous GN, Diabetic Nephropathy, and Amyloidosis [1]. * **Proliferative (Nephritic):** Post-Streptococcal GN (PSGN), Rapidly Progressive GN (RPGN), MPGN/MCGN, and IgA Nephropathy [1]. * **MPGN Hallmark:** "Tram-track" or "Double contour" appearance of the GBM due to mesangial interposition [2]. * **MPGN Type II (Dense Deposit Disease):** Associated with **C3 Nephritic Factor** and hypocomplementemia. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 915-921. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 925-926.
Question 122: Pauci-immune glomerulonephritis is seen in which of the following conditions?
- A. Post-transplant glomerulopathy
- B. Microscopic polyangiitis (Correct Answer)
- C. Henoch-Schonlein nephritis
- D. Lupus nephritis
Explanation: **Pauci-immune glomerulonephritis (GN)** is characterized by necrotizing glomerular inflammation with **minimal or no deposition of immune complexes** or antibodies on immunofluorescence (IF) or electron microscopy [1]. It is the hallmark of **ANCA-associated vasculitides** [1]. 1. **Why Microscopic Polyangiitis (MPA) is correct:** MPA is a small-vessel vasculitis strongly associated with **p-ANCA (anti-MPO)** [3]. In the kidneys, it presents as a focal segmental necrotizing GN that progresses to **Crescentic GN (Type III)** [2]. Because the pathogenesis is mediated by activated neutrophils rather than trapped immune complexes, IF shows a "pauci" (few) immune pattern [3]. Other examples include Granulomatosis with Polyangiitis (GPA) and Eosinophilic Granulomatosis with Polyangiitis (EGPA) [2]. 2. **Why other options are incorrect:** * **Post-transplant glomerulopathy:** Characterized by double contouring of the glomerular basement membrane (GBM) due to chronic antibody-mediated rejection; it is not a primary pauci-immune process. * **Henoch-Schönlein Purpura (HSP) / IgA Vasculitis:** This is an **immune-complex mediated** disease. IF characteristically shows granular **IgA deposits** in the mesangium [5]. * **Lupus Nephritis:** A classic example of **Type III Hypersensitivity**, showing a "Full House" pattern on IF (IgG, IgM, IgA, C3, and C1q deposits). **High-Yield Clinical Pearls for NEET-PG:** * **Crescentic GN Classification:** * **Type I:** Anti-GBM disease (Linear IgG deposits, e.g., Goodpasture syndrome) [4]. * **Type II:** Immune Complex mediated (Granular deposits, e.g., PSGN, SLE) [4]. * **Type III:** Pauci-immune (ANCA-associated) [1]. * **MPA vs. GPA:** MPA lacks the granulomatous inflammation and upper respiratory involvement typically seen in GPA (Wegener’s) [2]. * **Serology:** MPA is most commonly **p-ANCA** positive, while GPA is **c-ANCA (anti-PR3)** positive [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 917-918. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 536-537. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 518-519. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, p. 915. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 535-536.
Question 123: An 8-month-old male infant presents with progressive renal and hepatic failure. Despite intensive medical therapy, the infant dies. At the time of autopsy, the external surfaces of his kidneys are found to be smooth, but the cut section reveals numerous cysts that are lined up in a row. What is the mode of inheritance of this renal abnormality?
- A. Autosomal dominant
- B. Autosomal recessive (Correct Answer)
- C. X-linked dominant
- D. X-linked recessive
Explanation: The clinical presentation and autopsy findings are classic for **Autosomal Recessive Polycystic Kidney Disease (ARPKD)**. **Why Option B is Correct:** ARPKD typically presents in the neonatal period or infancy. The hallmark gross finding is a **smooth external surface** (unlike the bosselated/nodular surface in the adult form) with a cut section showing **radially arranged, cylindrical/fusiform cysts** that extend from the medulla to the cortex. These cysts are formed by the dilation of collecting ducts [1]. Crucially, ARPKD is almost always associated with **congenital hepatic fibrosis**, leading to the combined renal and hepatic failure seen in this infant. It is caused by mutations in the **PKHD1 gene** on chromosome 6, which encodes **fibrocystin** [1]. **Why Other Options are Incorrect:** * **Option A (Autosomal Dominant):** ADPKD (Adult-onset) usually presents in the 3rd or 4th decade of life. Grossly, the kidneys are massive and have a **multicystic, irregular (bosselated) surface** with no specific radial orientation of cysts. * **Options C & D (X-linked):** While some rare renal syndromes (like Alport syndrome) can be X-linked, the major cystic diseases of the kidney are not inherited via sex chromosomes. **NEET-PG High-Yield Pearls:** * **ARPKD Triad:** Bilateral enlarged smooth kidneys + Congenital Hepatic Fibrosis + Potter sequence (due to oligohydramnios). * **Imaging:** On ultrasound, ARPKD kidneys appear "bright" or echogenic due to numerous small cyst interfaces. * **Genetics:** ADPKD involves **PKD1** (85%, Chromosome 16) or **PKD2** (15%, Chromosome 4). ARPKD involves **PKHD1** (Chromosome 6) [1]. * **Survival:** If the infant survives the neonatal period, the primary long-term complication is portal hypertension due to hepatic fibrosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 952-953.
Question 124: A 40-year-old hypertensive male was admitted to the hospital with sudden onset of headache and altered sensorium. On examination, his blood pressure was observed to be 220/110 mm Hg. The patient died four hours later. What is the likely pathological finding in his kidneys?
- A. Small kidney with granular surface
- B. Small kidney with petechial hemorrhages (Correct Answer)
- C. Large kidney with waxy appearance
- D. Large kidney with granular surface
Explanation: ### Explanation The clinical presentation of severe hypertension (220/110 mm Hg) associated with neurological symptoms (headache, altered sensorium) and sudden death points toward a diagnosis of **Malignant Hypertension** (or Hypertensive Emergency) [1]. **1. Why Option B is Correct:** In Malignant Hypertension, the kidneys undergo rapid damage. The characteristic gross appearance is the **"Flea-bitten Kidney."** This is characterized by **petechial hemorrhages** on the cortical surface, which occur due to the rupture of arterioles or glomerular capillaries under extreme pressure. Histologically, this corresponds to **fibrinoid necrosis** of arterioles [3] and **hyperplastic arteriolosclerosis** (onion-skinning) [4]. While the kidneys may be normal-sized initially, they are often described as small if there was pre-existing chronic hypertension. **2. Why the Other Options are Incorrect:** * **Option A:** Small kidneys with a granular surface are characteristic of **Benign Nephrosclerosis** (chronic, stable hypertension) [2]. The granularity is due to alternating areas of ischemic tubular atrophy and compensatory hypertrophy of nephrons. * **Option C:** A large kidney with a waxy appearance is the classic description of **Renal Amyloidosis**. The "waxy" texture is due to the deposition of extracellular amyloid fibrils. * **Option D:** Large kidneys with a granular surface are not a standard presentation for hypertensive disease. Large kidneys are more typical of acute processes (like Acute Glomerulonephritis) or infiltrative diseases (like Amyloidosis or Polycystic Kidney Disease). ### NEET-PG High-Yield Pearls * **Flea-bitten Kidney Differential:** Malignant Hypertension, Subacute Bacterial Endocarditis (SBE), Polyarteritis Nodosa (PAN), and Henoch-Schönlein Purpura (HSP). * **Histology Hallmark:** Look for **"Onion-skinning"** (proliferation of smooth muscle cells) and **Fibrinoid Necrosis** in Malignant Hypertension [4]. * **Benign vs. Malignant:** Benign hypertension causes *Hyaline* arteriolosclerosis; Malignant hypertension causes *Hyperplastic* arteriolosclerosis [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 276-277. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 541-542. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 498-499. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, p. 945.
Question 125: Mesangial deposits of Lambda chain are seen in which condition?
- A. Amyloidosis (Correct Answer)
- B. Focal segmental glomerulosclerosis
- C. Membranoproliferative glomerulonephritis
- D. Membranous nephropathy
Explanation: **Explanation:** **Amyloidosis** (specifically AL type) is characterized by the extracellular deposition of misfolded monoclonal light chains [3]. In about 75% of AL amyloidosis cases, the **Lambda (λ) light chain** is the precursor protein [1] (unlike multiple myeloma, where Kappa is more common). These light chains deposit in the renal mesangium and capillary loops, eventually forming organized 7–12 nm non-branching fibrils [2]. On immunofluorescence (IF), these show strong positivity for Lambda light chains. **Why other options are incorrect:** * **Focal Segmental Glomerulosclerosis (FSGS):** This is a podocytopathy. IF is typically negative, though non-specific IgM and C3 trapping may be seen in scarred areas. It does not involve light chain deposition. * **Membranoproliferative Glomerulonephritis (MPGN):** This is characterized by the deposition of immune complexes (IgG/IgM) and complement (C3) or C3 alone (in C3 glomerulopathy). It is not defined by isolated light chain deposits. * **Membranous Nephropathy:** This is caused by subepithelial deposits of IgG (usually IgG4) and C3. In primary cases, these are directed against the PLA2R receptor. **High-Yield Clinical Pearls for NEET-PG:** * **Staining:** Amyloid shows **Apple-green birefringence** under polarized light after **Congo Red** staining [4]. * **Electron Microscopy:** Shows haphazardly arranged, **non-branching fibrils** (7–12 nm) [2]. * **LCDD vs. Amyloidosis:** In Light Chain Deposition Disease (LCDD), **Kappa (κ)** chains are more common, and they do *not* form fibrils [1] or stain with Congo Red. * **Gold Standard:** The most sensitive site for biopsy in suspected systemic amyloidosis is the **abdominal fat pad** or rectal mucosa, though renal biopsy is definitive for renal involvement. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 942-943. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 533-534. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 264-266. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 268-269.
Question 126: Which of the following is MOST relevant in renal vascular hypertension?
- A. Aldosterone (Correct Answer)
- B. Renin
- C. Hypokalemia
- D. Angiotensin II
Explanation: **Explanation:** Renovascular hypertension is caused by renal artery stenosis, which leads to decreased renal perfusion [1]. This triggers the **Renin-Angiotensin-Aldosterone System (RAAS)** [1]. While Renin and Angiotensin II are mediators in this cascade, **Aldosterone** is considered the most relevant end-effector in the context of clinical pathology and the maintenance of hypertension. 1. **Why Aldosterone is Correct:** Aldosterone acts on the distal convoluted tubules and collecting ducts to increase sodium and water reabsorption while excreting potassium and hydrogen ions [2]. This volume expansion, coupled with the systemic effects of the RAAS activation, is the primary driver of sustained hypertension [1]. In medical exams, when asked for the "most relevant" factor in the context of the hormonal profile of this condition, Aldosterone represents the definitive secondary hyperaldosteronism that characterizes the disease. 2. **Why other options are incorrect:** * **Renin:** It is the initiating enzyme (secreted by Juxtaglomerular cells), but it acts as a catalyst rather than the final effector of volume expansion [1]. * **Angiotensin II:** While it is a potent vasoconstrictor and stimulates aldosterone release, it has a very short half-life and is a middle step in the cascade [1]. * **Hypokalemia:** This is a *consequence* of high aldosterone levels (due to potassium wasting), not a cause or the most relevant factor in the hypertensive mechanism itself. **High-Yield Clinical Pearls for NEET-PG:** * **Goldblatt Kidney:** The classic experimental model for renovascular hypertension. * **Causes:** Atherosclerosis (common in elderly) and Fibromuscular Dysplasia (common in young females; "string of beads" appearance on angiography) [1]. * **Diagnosis:** Digital Subtraction Angiography (Gold Standard); Doppler Ultrasound (Initial). * **Key Finding:** Elevated Plasma Renin Activity (PRA) in the affected renal vein. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 945-946. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1129-1130.
Question 127: Which of the following is seen in nephrotic syndrome?
- A. Low serum calcium (Correct Answer)
- B. Raised AT–III
- C. Low lipid
- D. Platelet activation
Explanation: **Explanation:** Nephrotic syndrome is characterized by massive proteinuria (>3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia [1]. **1. Why Low Serum Calcium is correct:** In nephrotic syndrome, hypoalbuminemia is a hallmark feature [1]. Since approximately 40-50% of serum calcium is bound to albumin, a decrease in serum albumin leads to a decrease in the **total serum calcium** levels. Furthermore, there is urinary loss of **Vitamin D-binding protein**, leading to a deficiency of 25-hydroxyvitamin D3, which further impairs intestinal calcium absorption. (Note: Ionized calcium levels usually remain normal). **2. Analysis of Incorrect Options:** * **B. Raised AT-III:** Incorrect. There is actually a **loss of Antithrombin III (AT-III)** in the urine due to its low molecular weight. This deficiency, along with increased synthesis of clotting factors, contributes to a hypercoagulable state and increased risk of renal vein thrombosis. * **C. Low lipid:** Incorrect. **Hyperlipidemia** is a classic feature. Hypoalbuminemia triggers the liver to increase the synthesis of lipoproteins (VLDL, LDL) to maintain oncotic pressure, and there is decreased clearance of lipids due to reduced lipoprotein lipase activity. * **D. Platelet activation:** While nephrotic syndrome is a prothrombotic state, "Platelet activation" is a secondary physiological process rather than a primary diagnostic laboratory finding of the syndrome itself. The question focuses on the biochemical changes directly resulting from protein loss. **NEET-PG High-Yield Pearls:** * **Most common cause in children:** Minimal Change Disease (MCD) [2]. * **Most common cause in adults:** Focal Segmental Glomerulosclerosis (FSGS) (globally) [2] or Membranous Nephropathy [2]. * **Hypercoagulability:** Most commonly associated with **Membranous Nephropathy**; Renal Vein Thrombosis is a classic complication. * **Urinary sediment:** Characterized by "Fatty casts" and "Maltese cross" appearance under polarized light due to lipiduria. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 126-127. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 919-921.
Question 128: What is the commonest histological finding in hypertensive nephrosclerosis?
- A. Proliferative endarteritis
- B. Necrotizing arteriolitis
- C. Hyaline arteriosclerosis (Correct Answer)
- D. Cystic medial necrosis
Explanation: **Explanation:** **Hypertensive nephrosclerosis** (specifically benign nephrosclerosis) is the renal manifestation of chronic, long-standing essential hypertension. **1. Why Hyaline Arteriosclerosis is correct:** Chronic hemodynamic stress (high blood pressure) causes plasma proteins to leak across the injured vascular endothelium into the vessel wall [1]. This, combined with increased smooth muscle cell matrix production, results in the characteristic **homogeneous, pink, "glassy" thickening** of the arteriolar walls known as **hyaline arteriosclerosis** [2]. This narrows the lumen, leading to chronic ischemia, tubular atrophy, and interstitial fibrosis [1], giving the kidney a "grainy" or "leather-grain" appearance. [3] **2. Why the other options are incorrect:** * **Proliferative endarteritis & Necrotizing arteriolitis:** These are the hallmarks of **Malignant Hypertension** (hypertensive emergency). Proliferative endarteritis shows "onion-skin" concentric laminations [2], while necrotizing arteriolitis involves fibrinoid necrosis of the vessel wall. * **Cystic medial necrosis:** This is a degenerative change of the large arterial media (notably the aorta), characterized by the loss of elastic fibers and smooth muscle. It is classically associated with **Marfan Syndrome** and aortic dissection, not hypertensive nephrosclerosis. **High-Yield Clinical Pearls for NEET-PG:** * **Benign Nephrosclerosis:** Associated with Hyaline Arteriosclerosis; kidneys are symmetrically shrunken with a **finely granular surface** [1]. * **Malignant Nephrosclerosis:** Associated with Hyperplastic Arteriolitis (Onion-skinning); kidneys show **"flea-bitten"** appearance (petechial hemorrhages). * **Key Histology:** Hyaline change is most prominent in the **afferent arterioles**. * **Demographics:** More common and severe in African Americans and patients with concomitant Diabetes Mellitus. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 943-945. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 498-499. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 541-542.
Question 129: Which of the following is NOT a steroid-responsive glomerulonephritis?
- A. Post-streptococcal glomerulonephritis
- B. Minimal change disease
- C. Membranoproliferative glomerulonephritis (Correct Answer)
- D. Focal segmental glomerulosclerosis
Explanation: ### Explanation The responsiveness of glomerulonephritis (GN) to corticosteroids depends on the underlying pathophysiology—specifically whether the disease is driven by reversible podocyte injury or an inflammatory process that can be suppressed by steroids. **Why Option C is Correct:** **Membranoproliferative Glomerulonephritis (MPGN)** is notoriously resistant to steroid monotherapy. Whether Type I (immune-complex mediated) or Type II (Dense Deposit Disease/complement-mediated), MPGN involves structural changes like "tram-tracking" of the basement membrane and persistent complement activation. Treatment usually focuses on managing the underlying cause or using aggressive immunosuppressants (like Mycophenolate Mofetil or Rituximab) rather than steroids alone, which show poor efficacy in inducing remission [5]. **Why the Other Options are Incorrect:** * **Minimal Change Disease (MCD):** This is the "prototype" of steroid-responsive nephrotic syndrome [1]. Over 90% of children achieve complete remission with corticosteroids, as they stabilize podocyte function [1], [2]. * **Focal Segmental Glomerulosclerosis (FSGS):** While more resistant than MCD, steroids remain the **first-line** treatment [2]. A significant subset of patients (especially those with primary FSGS) are "steroid-sensitive," though many may eventually become steroid-dependent or resistant [3]. * **Post-streptococcal Glomerulonephritis (PSGN):** This is a self-limiting condition. While steroids are not typically *indicated* because the disease resolves spontaneously with supportive care, it is not classified as "steroid-resistant" in the same pathological sense as MPGN. (Note: In the context of NEET-PG, if a question asks for a disease that does *not* respond to steroids among chronic/progressive GN, MPGN is the classic answer). **High-Yield Clinical Pearls for NEET-PG:** * **MCD:** Most common cause of nephrotic syndrome in children; characterized by effacement of podocyte foot processes on Electron Microscopy [2]. * **MPGN:** Characterized by **hypocomplementemia** (low C3). Type II is specifically associated with **C3 Nephritic Factor**. * **FSGS:** Most common cause of nephrotic syndrome in adults in many regions; often associated with HIV, heroin use, and obesity [4]. * **Rule of Thumb:** Podocytopathies (MCD, FSGS) are generally more steroid-responsive than "proliferative" or "structural" glomerulopathies (MPGN) [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 922-923. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 927-928. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 530-531. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 531-532. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 926-927.
Question 130: Which of the following proteins is most commonly associated with steroid-resistant nephrotic syndrome?
- A. Nephrin
- B. Alpha-actinin-4
- C. Podocin (Correct Answer)
- D. Transient Receptor Potential 6
Explanation: ### Explanation The correct answer is **Podocin**. **1. Why Podocin is Correct:** Podocin is a protein encoded by the **NPHS2** gene, located on chromosome 1q25-31. It is a component of the slit diaphragm of the glomerular podocyte [1]. Mutations in the NPHS2 gene are the most common genetic cause of **Steroid-Resistant Nephrotic Syndrome (SRNS)** presenting in childhood. Clinically, these patients typically manifest with **Focal Segmental Glomerulosclerosis (FSGS)** and do not respond to corticosteroid therapy, often progressing to end-stage renal disease (ESRD) [1], [2]. **2. Analysis of Incorrect Options:** * **Nephrin (Option A):** Encoded by the **NPHS1** gene. Mutations in nephrin cause **Congenital Nephrotic Syndrome of the Finnish type**. While it presents early (infancy), it is distinct from the classic NPHS2-associated SRNS. * **Alpha-actinin-4 (Option B):** Mutations in the *ACTN4* gene cause an **autosomal dominant** form of FSGS. It typically presents later in adolescence or adulthood, rather than being the "most common" association for SRNS. * **TRPC6 (Option D):** Transient Receptor Potential 6 is a cation channel. Mutations lead to adult-onset FSGS via increased calcium signaling in podocytes. **3. NEET-PG High-Yield Pearls:** * **NPHS1 (Nephrin):** Finnish type Congenital Nephrotic Syndrome (Chromosome 19q). * **NPHS2 (Podocin):** Steroid-Resistant Nephrotic Syndrome / FSGS (Chromosome 1q). * **Slit Diaphragm:** The primary filtration barrier for proteins; Nephrin and Podocin are its most critical structural components [1]. * **Clinical Tip:** If a pediatric patient with nephrotic syndrome fails to respond to steroids, the most likely underlying pathology is FSGS, and the most likely genetic mutation involves Podocin [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 919-924. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 530-531.
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Congenital Anomalies of the Kidney
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Glomerular Diseases
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Tubular and Interstitial Diseases
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Cystic Diseases of the Kidney
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Urinary Tract Obstruction and Stones
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Renal Tumors
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Kidney in Systemic Diseases
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Renal Transplantation Pathology
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Urinary Tract Infections
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