**Question:** IgA nephropathy is characterised by:

**Core Concept:** IgA nephropathy is a chronic kidney disease caused by the deposition of IgA immune complex in the glomeruli, leading to inflammation and damage to the kidneys.

**Why the Correct Answer is Right:** IgA nephropathy is primarily caused by the deposition of IgA immunoglobulins in the mesangium of glomeruli, resulting in inflammation and damage to the glomeruli. This leads to progressive deterioration of kidney function over time.

**Why Each Wrong Option is Incorrect:**

A. **Incorrect:** This option is incorrect because IgA nephropathy is primarily characterized by the deposition of IgA immune complexes, not IgG or IgM.

B. **Incorrect:** Although glomerular hypertension and proteinuria are common features of IgA nephropathy, they are not the primary characteristics of the disease. The focus should be on the IgA immune complex deposition.

C. **Incorrect:** This option is incorrect because IgA nephropathy is primarily characterized by the deposition of IgA immune complexes, not IgG or IgM.

D. **Incorrect:** Although renal insufficiency can occur in advanced cases of IgA nephropathy, it is not the primary feature of the disease. The focus should be on the IgA immune complex deposition and subsequent inflammation.

**Clinical Pearl / High-Yield Fact:** IgA nephropathy is the most common primary glomerulonephritis in the western world and is associated with increased risk of hypertension, end-stage renal disease, and cardiovascular complications.

**Correct Answer:** D. **Correct:** IgA nephropathy is characterized by the deposition of IgA immune complexes, leading to inflammation and damage to the glomeruli. This results in hypertension, proteinuria, and renal insufficiency as the disease progresses.

**Explanation:** IgA nephropathy is a chronic kidney disease caused by the deposition of IgA immune complexes in the mesangium of glomeruli, leading to inflammation and damage. This leads to hypertension, proteinuria, and renal insufficiency as the disease progresses. The correct answer is option D, which highlights the primary feature of IgA nephropathy, i.e., the deposition of IgA immune complexes in the glomeruli. The other options (A, B, and C) are incorrect because they focus on secondary features (hypertension, proteinuria, and renal insufficiency) rather than the primary cause (IgA immune complex deposition).