What is amyloidosis?

Updated: May 09, 2019
  • Author: Robert O Holmes, Jr, DO; Chief Editor: Herbert S Diamond, MD  more...
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Amyloidosis is a clinical disorder caused by extracellular and/or intracellular deposition of insoluble abnormal amyloid fibrils that alter the normal function of tissues. Only 10% of amyloidosis deposits consist of components such as glycosaminoglycans (GAGs), apolipoprotein-E (apoE), and serum amyloid P-component (SAP), while nearly 90% of the deposits consist of amyloid fibrils that are formed by the aggregation of misfolded proteins. These proteins either arise from proteins expressed by cells at the deposition site (localized), or they precipitate systemically after production at a local site (systemic). [5] In humans, about 23 different unrelated proteins are known to form amyloid fibrils in vivo. [6]

Many mechanisms of protein function contribute to amyloidogenesis, including “nonphysiologic proteolysis, defective or absent physiologic proteolysis, mutations involving changes in thermodynamic or kinetic properties, and pathways that are yet to be defined.” [6]

For patient education information, see the Brain and Nervous System Center, as well as Mad Cow Disease and Variant Creutzfeldt-Jakob Disease.

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