IgA nephropathy has all the following characteristics except –
**Core Concept**
IgA nephropathy, also known as Berger's disease, is a kidney disease characterized by the deposition of IgA antibodies in the glomeruli, leading to inflammation and damage. This condition is a common cause of recurrent hematuria, particularly after respiratory or gastrointestinal infections.
**Why the Correct Answer is Right**
IgA nephropathy typically presents with episodic hematuria, often in association with IgA levels that rise in response to infections. The disease is mediated by the deposition of IgA1 molecules, which are particularly susceptible to proteolytic cleavage, leading to the formation of galactose-deficient IgA1 (Gd-IgA1) that triggers an immune response. The mesangial deposition of IgA and complement components, such as C3, is a hallmark of the disease.
**Why Each Wrong Option is Incorrect**
**Option A:** IgA nephropathy is primarily characterized by the deposition of IgA1 antibodies in the glomeruli, and IgA2 deposition is not a hallmark of the disease.
**Option B:** IgA nephropathy is typically associated with mesangial proliferation and deposition of IgA and complement components, rather than pure membranous nephropathy.
**Option C:** IgA nephropathy is not primarily associated with the deposition of IgG or C3 alone, but rather the combination of IgA and complement components, particularly C3.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that IgA nephropathy can be triggered by infections, particularly respiratory and gastrointestinal pathogens, which can cause a rise in IgA levels and exacerbate the disease.
**Correct Answer:** A.