Amyloidosis

Amyloidosis is a rare disease that results from the buildup of misfolded proteins known as amyloids. When proteins that are normally dissolvable in water fold to become amyloids, they become insoluble and deposit in organs or tissues, disrupting normal function. The type of protein that is misfolded and the organ or tissue in which the misfolded proteins are deposited determine the clinical manifestations of amyloidosis.

There are four main types of amyloidosis, each due to the deposition of a specific protein. The most common type is AL amyloidosis, caused by the deposition of light chain proteins produced by plasma cells in different disease states. The second most common is AA amyloidosis due to the accumulation of S amyloid A protein or SAA, which occurs in association with chronic infections - e.g. tuberculosis - or inflammatory illnesses such as rheumatoid arthritis. The third and the fourth type are due to the deposition of a genetically defective or normal form of a protein called transthyretin respectively. Other minor forms of amyloid are also known.