Serum amyloid A (SAA)

Author: Sheren Younes, M.D. (see Authors page)
Editorial Board Member Review: Lauren N. Stuart, M.D., M.B.A.

Revised: 2 November 2017, last major update September 2017

Copyright: (c) 2002-2017,, Inc.

PubMed Search: (Serum amyloid A [title]) (SAA [title]) "loattrfree full text"[sb]

Cite this page: Younes, S. Serum amyloid A (SAA). website. Accessed October 19th, 2018.
  • Acute phase protein, which has diagnostic, therapeutic and prognostic implications in a wide variety of diseases
  • First recognized in serum with its cross reactivity with antisera to amyloid AA of secondary amyloid; both proteins have precursor / product relationship
  • 104 AA residues
  • N terminal is usually 76 residues identical to protein AA
  • Four genes encode SAA isoforms (SAA1, SAA2, SAA3 and SAA4); it spans 10 kb within the p15.1 region of chromosome 11
  • Each gene encodes a different protein
  • Synthesized in liver
  • In blood, SAA is associated with HDL in acute phase response
  • Expressed variants of protein and mRNA in different tissues, not only liver, also breast, colon, adipocytes, brain (Curr Med Chem 2016;23:1725)
Role of SAA in pathogenesis of different diseases
Role in pathology
Microscopic (histologic) images

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Fig. H: SAA in hepatic adenoma