Amyloidosis

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Amyloidosis
Classification and external resources
Small bowel duodenum with amyloid deposition congo red 10X
ICD-10 E85.
ICD-9 277.3
DiseasesDB 633
eMedicine med/3377  med/3888
MeSH D000686

In medicine, amyloidosis refers to a variety of conditions in which amyloid proteins are abnormally deposited in organs and/or tissues, causing disease. A protein is amyloid if, due to an alteration in its secondary structure, it takes on a particular insoluble form, called the beta-pleated sheet.[1]

The term "amyloidosis" refers to a histological finding occurring in several different disease processes that have little in common with each other, and without additional information, the finding is of limited clinical use.[2]

Contents

[edit] Diagnosis

Amyloid can be diagnosed on microscopic examination of affected tissue. Amyloid deposits can be identified histologically by Congo red staining[3] and viewing under polarized light where amyloid deposits produce a distinctive 'apple green birefringence'. Further, specific tests are available to more precisely identify the amyloid protein. Biopsies are taken from affected organs (for example, the kidney), or often in the case of systemic amyloid, from the rectum or anterior abdominal adipose tissue.

In addition, all amyloid deposits contain serum amyloid P component (SAP),[4] a circulating protein of the pentraxin family. Radionuclide SAP scans have been developed which can anatomically localize amyloid deposits in patients.

[edit] Classification of amyloid

Approximately 25 different proteins are known that can form amyloid in humans. Most of them are constituents of the plasma.

Different amyloidoses can be systemic (affecting many different organ systems) or organ-specific. Some are inherited, due to mutations in the precursor protein. Other forms are due to different diseases causing overabundant or abnormal protein production-such as with over production of immunoglobulin light chains in multiple myeloma (termed AL amyloid), or with continuous overproduction of acute phase proteins in chronic inflammation (which can lead to AA amyloid).

There are at least 15 biologically distinct forms of amyloid, some more clinically significant than others. Following is a brief description of the more common types of amyloid:

Abb. Amyloid type Description
AL amyloid light chain Contains immunoglobulin light-chains (λ,κ) derived from plasma cells
AA amyloid associated Non-immunoglobulin protein made in the liver
Aβ β amyloid Found in Alzheimer disease brain lesions
ATTR Transthyretin A mutant form of a normal serum protein that is deposited in the genetically determined familial amyloid polyneuropathies. TTR is also deposited in the heart in senile systemic amyloidosis.[5]
Aβ2 m β2 microglobulin Not to be confused with Aβ, β2m is a normal serum protein, part of major histocompatability complex (MHC) Class 1 molecules. Can occur in long term haemodialysis.
PrP Prion related protein In Prion diseases, misfolded prion proteins deposit in tissues and resemble amyloid proteins.

OMIM includes the following:

OMIM Gene Name Number
176300 TTR Senile systemic amyloidosis (type 1)
105120 GSN Finnish type amyloidosis (type 5)
105150 CST3 Cerebral amyloid angiopathy, Icelandic type (type 6)
105210 TTR Leptomeningeal amyloidosis (type 7)
105200 APOA1, FGA, LYZ Familial visceral amyloidosis (type 8)
105250 OSMR Primary cutaneous amyloidosis (type 9)
176500 ITM2B Cerebral amyloid angiopathy, British type -
609065, 605714 APP Dutch type / Italian type / Iowa type -

[edit] Classification of amyloidosis

The amyloidoses can be classified as systemic or localised, primary or secondary, or according to which type of amyloid is deposited. By convention, a combination of these approaches are used clinically.

  • Systemic amyloidoses are those which affect more than one body organ or system. Localised amyloidoses affect only one body organ or tissue type.
  • Primary amyloidoses arise from a disease with disorderd immune cell function such as multiple myeloma and other immunocyte dyscrasias.

Secondary (reactive) amyloidoses are those occurring as a complication of some other chronic inflammatory or tissue destructive disease.

  • The different types of amyloid deposited (see table, above) may be either primary or secondary, systemic or localised.

[edit] Systemic amyloidosis

The common systemic amyloidoses:

Category Amyloid type Precursor protein Associated diseases
Immunocyte dyscrasias (primary amyloidosis) AL Immunoglobin light chains (Bence Jones protein) Multiple myeloma, other monoclonal B-cell proliferations
Reactive systemic (secondary amyloidosis) AA SAA Chronic inflammatory conditions
Haemodialysis associated Aβ2 m β2 microglobulin Chronic renal failure
Hereditary AA SAA Familial mediterranean fever
Hereditary ATTR transthyretin Familial amyloidotic polyneuropathies
Systemic senile amyloidosis ATTR transthyretin Systemic senile amyloidosis

[edit] Organ-specific amyloidosis

Main article: Organ-limited amyloidosis

In almost all of the organ-specific pathologies, there is significant debate as to whether the amyloid plaques are the causal agent of the disease or instead a downstream consequence of a common idiopathic agent.

[edit] Famous People who have contracted Amyloidosis

[edit] References

  1. ^ Atlas of Pathology.
  2. ^ Gertz MA (June 2004). "The classification and typing of amyloid deposits". Am. J. Clin. Pathol. 121 (6): 787–9. doi:10.1309/TR4L-GLVR-JKAM-V5QT. PMID 15198347. 
  3. ^ Satoskar AA, Burdge K, Cowden DJ, Nadasdy GM, Hebert LA, Nadasdy T (June 2007). "Typing of amyloidosis in renal biopsies: diagnostic pitfalls". Arch. Pathol. Lab. Med. 131 (6): 917–22. PMID 17550319. 
  4. ^ Togashi S, Lim SK, Kawano H, et al (November 1997). "Serum amyloid P component enhances induction of murine amyloidosis". Lab. Invest. 77 (5): 525–31. PMID 9389795. 
  5. ^ Hassan W, Al-Sergani H, Mourad W, Tabbaa R (2005). "Amyloid heart disease. New frontiers and insights in pathophysiology, diagnosis, and management". Tex Heart Inst J 32 (2): 178–84. PMID 16107109. 

[edit] External links

v • d • e
Metabolic disease: amyloidosis (E85, 277.3)
Forms of amyloid
Systemic amyloidosis
Organ-limited amyloidosis