Linear deposition of IgG on glomerular basement membrane is seen in –
💡 Explanation
## **Core Concept**
The question tests the understanding of immunofluorescence patterns in kidney diseases, specifically the linear deposition of IgG on the glomerular basement membrane (GBM). This pattern is characteristic of diseases where autoantibodies target the GBM. The GBM is a critical component of the glomerulus, and its integrity is essential for proper kidney function.
## **Why the Correct Answer is Right**
The correct answer, **Goodpasture's syndrome**, is a rare autoimmune disease characterized by the production of autoantibodies against the alpha-3 chain of type IV collagen in the GBM. These autoantibodies, typically of the IgG class, deposit linearly along the GBM, leading to inflammation and damage. This results in rapidly progressive glomerulonephritis and sometimes pulmonary hemorrhage. The linear deposition of IgG on immunofluorescence microscopy is diagnostic of Goodpasture's syndrome.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not correspond to Goodpasture's syndrome.
- **Option B:** This option is incorrect as it does not match the description of linear IgG deposition on GBM.
- **Option C:** This option is incorrect because it also does not correspond to the condition described.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Goodpasture's syndrome often presents with a combination of renal and pulmonary symptoms, such as hematuria, proteinuria, and hemoptysis. Rapid diagnosis and treatment are crucial to prevent irreversible damage. The presence of anti-GBM antibodies on serological testing supports the diagnosis.