AA amyloidosis (reactive/secondary amyloidosis) develops in patients with chronic inflammatory conditions. The serum precursor protein that forms AA fibrils is:
- A Serum amyloid P component (SAP)
- B Immunoglobulin light chains (Bence-Jones protein)
- C Serum amyloid A (SAA), an acute-phase reactant ✓
- D Transthyretin (TTR)
Correct answer: C. Serum amyloid A (SAA), an acute-phase reactant
Explanation
AA amyloidosis is composed of AA protein derived from serum amyloid A (SAA), a liver-produced acute-phase reactant that is chronically elevated in rheumatoid arthritis, tuberculosis, chronic osteomyelitis, and familial Mediterranean fever. AL amyloidosis (most common systemic form) is derived from immunoglobulin light chains in plasma cell dyscrasias. Transthyretin forms ATTR amyloidosis (familial and senile cardiac). SAP is a universal component of all amyloid deposits but is not the fibril-forming precursor.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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