Amyloidosis
Viewed 391 times
-
The term amyloidosis includes a group of disorders caused by abnormal folding, clumping, (aggregation) and/or accumulation of particular proteins (amyloids, fibrous proteins and their precursors) outside of the cell (extracellular), but within the tissues of various organs of the body. The accumulated amyloid causes the progressive malfunction of the affected organ. Normally, proteins are broken down at about the same rate as they are produced, however these unusually stable proteins are deposited more rapidly than they can be broken down. The accumulation may be localized, general, or systemic. These are listed below:
The most widely used classification of the amyloidoses is based on the biochemical nature of the fiber-like protein structures (fibrils) and on the nature of the precursor proteins that give rise to the amyloids (See Disorder Subdivisions section). The different amyloidoses are named by combining the upper case ‘A’ (for amyloid) with an abbreviation of the name of the protein that makes up the fibril. There are at least twenty (20) different types of fibrils that make up the human amyloidoses, and each is responsible for a unique clinical presentation.
Older discussions of amyloidosis refer often to primary amyloidosis or to myeloma-associated amyloidosis, the fibril protein of each of which is an immunoglobulin light chain peptide or fragment. The newer classification labels both of these as light chain amyloidosis or AL. Similarly, what had been classified as secondary amyloidosis, that is amyloidosis as secondary to another disorder such as familial Mediterranean fever, rheumatoid arthritis and other inflammatory diseases are now known as A amyloidosis or AA. Most cases of senile cardiac amyloidosis or familial amyloid neuropathy have fibrils which consist of transport protein transthyretin and are now classified as ATTR.
The Light chain amyloidosis (AL) form of the disorder occurs most often, but not always, in association with myelomas, that is, multiple tumors of the bone marrow. AL affects the kidney, heart, intestinal tract, liver and/or spleen. Kidney or cardiac involvement may result in renal or congestive heart failure, respectively.
The AA form of amyloidosis is frequently associated with chronic inflammatory disease, such as rheumatoid arthritis, chronic infections or familial Mediterranean fever. AA Amyloidosis also affects the kidneys, liver and spleen. The adrenal glands, lymph nodes, and vascular system may be become involved as well. When some inflammatory diseases are treated with recurrent injections, the inflammation of the skin that occurs seems to induce AA Amyloidosis. Malfunctioning of the kidneys, as in nephrotic syndrome and kidney (renal) failure, causes the most fatalities in AA Amyloidosis. This type of Amyloidosis is reported in approximately one percent of cases of chronic inflammatory diseases in the United States.
Beta2-microglobulin amyloidosis (Aß2M) or Hemodialysis-associated amyloidosis is seen in patients who have experienced long-term kidney dialysis which is a procedure in which accumulated impurities or wastes in the blood are removed by mechanical filtration.
The Familial or Hereditary Amyloidoses are a series of genetically transmitted diseases that typically affect the kidney, heart, skin, and other organs of the body.
