**Core Concept:** Fibronectin nephropathy is a rare clinical entity characterized by immune complex glomerulonephritis due to the deposition of immune complexes containing fibronectin, which is a plasma glycoprotein. It is associated with various conditions, including systemic lupus erythematosus, antiphospholipid syndrome, and hepatitis C virus infection.

**Why the Correct Answer is Right:**

Correct Answer: D (None of the above)

Fibronectin nephropathy typically presents with nephrotic syndrome, hematuria, hypertension, and progressive renal dysfunction. The correct answer is right because the features listed are common among fibronectin nephropathy patients but are not unique to this condition. Other features that are specific to fibronectin nephropathy include:

- Presence of elevated serum fibronectin levels
- Positive antifibronectin antibodies in the serum
- Evidence of immune complex deposition in the glomeruli on renal biopsy

**Why Each Wrong Option is Incorrect:**

A. Presence of elevated serum fibronectin levels: All patients with fibronectin nephropathy have elevated serum fibronectin levels, making this incorrect.

B. Positive antifibronectin antibodies in the serum: Although antifibronectin antibodies are often present in fibronectin nephropathy, they are not unique to this condition. They can also be found in other conditions like systemic lupus erythematosus, which is why this option is incorrect.

C. Evidence of immune complex deposition in the glomeruli on renal biopsy: While immune complex deposition is a hallmark of fibronectin nephropathy, it is also found in other conditions like lupus nephritis. This makes this option incorrect.

**Clinical Pearl:** Antibodies to fibronectin are often present in patients with fibronectin nephropathy. However, these antibodies are not specific to this condition and can also be found in other conditions such as systemic lupus erythematosus. Therefore, it is essential to consider other differential diagnoses when evaluating a patient with fibronectin nephropathy-like symptoms and signs.