What is amyloidosis?
Amyloidosis describes diseases characterized by the abnormal deposition of fibrils in extracellular tissues derived from an abnormal protein that is bound to serum amyloid P protein.
When this abnormal protein is a LC (usually λ), it is known as primary or AL amyloidosis. Other causes include the hereditary/genetic (AH; e.g., transthyretin) or secondary amyloidosis when chronic inflammation (e.g., familial Mediterranean fever) is associated with increased serum amyloid A protein (AA amyloid). These fibrils form tissue deposits within the body, especially the kidney, heart, liver, nerves, and gut. Although associated with myeloma in around 10% of patients, the majority present with organ dysfunction as a result of tissue infiltration rather than bone destruction.