- Amyloidosis is the general term used to refer to the extracellular tissue deposition of highly ordered fibrils composed of low molecular weight subunits of a variety of proteins, many of which, in their native form, circulate as normal constituents of plasma.
- Amyloid deposits may result in a wide range of clinical manifestations depending upon their type, location, and amount.
- In the genesis of amyloid deposits, previously soluble precursor peptides undergo conformational changes that lead to the adoption of a predominantly antiparallel beta-pleated sheet configuration, allowing them to stack as protofilaments in a twisted fibrillar configuration
- Amyloid has a characteristic gross pathologic and microscopic appearance, demonstrating birefringence with polarized light microscopy of Congo red stained tissue, which may have a typical “apple-green” dichroic appearance
- One third of amyloid disease is hereditary, in which case there is normally an early age of onset. Half of amyloid-related diseases are sporadic and have a late age of onset – in these cases, the protein aggregation may be associated with aging-related decline in protein regulation. Some medical treatments are associated with amyloid disease, but this is rare