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Pathogenesis of AA amyloidosis

Peter D Gorevic, MD
Section Editor
Helen J Lachmann, MA, MB, BChir, MD, FRCP, FRCPath
Deputy Editor
Paul L Romain, MD


AA amyloid results from the deposition in tissue of serum amyloid A (SAA) protein, which is a major acute phase reactant. Amyloidosis encompasses a group of diseases caused by misfolding and extracellular accumulation of proteins as fibrillar deposits. These fibrils stain with Congo red and produce pathognomonic green birefringence when viewed by microscopy under crossed polarized light. The process of amyloid formation and deposition causes tissue toxicity and progressive organ dysfunction.

The pathogenesis of AA amyloidosis is presented here. The clinical manifestations, diagnosis, and treatment of this disorder, an overview of amyloidosis, and the pathogenesis of other forms of amyloidosis are discussed separately. (See "Causes and diagnosis of AA amyloidosis and relation to rheumatic diseases" and "Treatment of AA (secondary) amyloidosis" and "Overview of amyloidosis".)


All forms of amyloidosis, including AA amyloidosis, are characterized by codeposition of other molecules, including [1,2]:

Serum amyloid P component (SAP), a member of the pentraxin family that includes C-reactive protein

Glycosaminoglycans, notably heparan sulfate

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Literature review current through: Nov 2017. | This topic last updated: May 04, 2017.
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