The diagnosis of amyloidosis depends on finding deposits with congo red birefringence in affected tis-sue.These deposits comprise fibrils of highly ordered proteins or protein fragments that generally contain prominent β-pleated sheet domains. Many proteins have regions that can aggregate into amyloid fibrils.Often only a small fragment of a larger molecule is compatible with fibril geometry and thus fibril formation occurs after cleaving the parent protein. Amyloid deposits can be found in any tissue.However, some depostis have no pathologic consequence while others can cause serious organ dysfunction by interrupting individual cellular physiology, cell-cell interactions and/or tissue integrity. When specific organ dysfunction has been identified, biopsy of that tissue often is the simplest diagnostic method(e.g.heart,kidney,liver). An alternative diagnostic approach for systermic amyloidosis is to examine tissue derived by aspiration of the abdominal fat pad. Both prognosis and treatment are based on identifying the protein in the fibril.Often, this protein can be iden-tified by immunofluorescence. Amyloid proteins vary widely and include immuno-globulins,inflammatory molecules, hormone precursors and inherited variants of normal serum proteins. Inherited forms of amyloidosis are uncommon but well-recognized. They often involve specific organs-e.g. heart,peripheral nerves,or blood vessels. Most have autosomal dominant inheritance.
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