Amyloidosis of the kidneys was diagnosed in a 58-year-old man who had chronic suppurative osteomyelitis. Which of the following proteins is the most likely precursor of amyloid fibers seen in the kidney biopsy?

Question

A. immunoglobulin light chain
B. serum amyloid A protein
C. transthyretin
D. amylin
E. A4 protein (A? protein)

Answer 1

B
Amyloidosis that develops in patients who have chronic supportive diseases is derived from serum amyloid A protein. Serum amyloid A protein is secreted by the liver, stimulated by the cytokines formed at the site of inflammation. Immunoglobulin light chain is the precursor of amyloid in multiple myeloma. Transthyretin, a liver-derived plasma protein, named so because it is involved in the transport of thyroid hormones and retinoic acid, is the precursor of amyloid deposited in nerves in familial neuropathy and senile cardiac amyloidosis. Amylin is found in the amyloid forming in some diabetics inside the islets of Langerhans. A4 protein is the precursor of amyloid found in the brain of patients affected by Alzheimer's disease.