In which of the following are linear IgA deposits in mesangium noted –
**Core Concept**
Linear IgA deposits in the mesangium are a hallmark of a specific immunoglobulin-mediated glomerulonephritis. This condition involves the deposition of linear IgA antibodies along the glomerular basement membrane, which is a characteristic feature of Linear IgA Disease (LAD).
**Why the Correct Answer is Right**
Linear IgA Disease is characterized by the presence of linear IgA antibodies that target the collagen IV network within the glomerular basement membrane. These antibodies are directed against the alpha-3 chain of collagen IV, leading to the activation of the complement system and subsequent mesangial deposits. The mesangium is a region of the glomerulus where the afferent and efferent arterioles converge, and it plays a crucial role in the regulation of capillary flow and filtration.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because IgA nephropathy, also known as Berger's disease, is characterized by mesangial IgA deposits, but they are not typically linear.
**Option B:** This option is incorrect because membranous nephropathy involves subepithelial deposits, not mesangial deposits.
**Option C:** This option is incorrect because minimal change disease is characterized by normal light microscopy findings, with no evidence of mesangial deposits.
**Clinical Pearl / High-Yield Fact**
Linear IgA Disease is a rare cause of nephritis, but it is an important consideration in patients with a history of skin lesions or autoimmune disorders.
**Correct Answer:** C. Linear IgA disease.