A 25-year-old woman is found to have AA amyloidosis complicating rheumatoid arthritis. The amyloid protein AA is derived from which circulating precursor protein?
- A Serum amyloid A protein (SAA), an acute-phase reactant ✓
- B Serum immunoglobulin light chains
- C Transthyretin (TTR) produced by the liver
- D Beta-2 microglobulin from haemodialysis
Explanation
AA amyloidosis (secondary amyloidosis) is derived from serum amyloid A (SAA), an acute-phase protein produced by the liver during chronic inflammatory states such as rheumatoid arthritis, chronic infections, familial Mediterranean fever, and IBD. Persistent SAA elevation leads to deposition of its N-terminal fragment as AA fibrils, predominantly in the kidneys, spleen, and adrenal glands. AL amyloid derives from immunoglobulin light chains (plasma cell dyscrasias); ATTR from transthyretin (hereditary or senile); Aβ2M from beta-2 microglobulin in dialysis-related amyloidosis.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.