Amyloidosis-associated kidney disease.

The amyloidoses are a group of disorders in which soluble proteins aggregate and deposit extracellularly in tissues as insoluble fibrils, causing progressive organ dysfunction. The kidney is one of the most frequent sites of amyloid deposition in AL, AA, and several of the hereditary amyloidoses. Amyloid fibril formation begins with the misfolding of an amyloidogenic precursor protein. The misfolded variants self-aggregate in a highly ordered manner, generating protofilaments that interact to form fibrils. The fibrils have a characteristic appearance by electron microscopy and generate birefringence under polarized light when stained with Congo red dye. Advances in elucidating the mechanisms of amyloid fibril formation, tissue deposition, and tissue injury have led to new and more aggressive treatment approaches for these disorders. This article reviews the pathogenesis, diagnosis, clinical manifestations, and treatment of the amyloidoses, focusing heavily on the renal aspects of each of these areas.