Clinical Presentation of Amyloid A Amyloidosis

Amyloid is an eosinophilic substance which appears “apple-green birefringence” in Congo red stained tissue sections under polarized light. This standard histological analysis is supported with immunochemistry technic using specific antibodies directed against most of the common human amyloid proteins, and also amyloid proteins can be identified with characteristic fibrillar appearance by electron microscopy (1). Amyloidosis is a name given to a heterogenous group diseases. It is caused by the extracellular amyloid deposition as insolubl fibrillar aggregates that destroy normal tissue architecture and interfere normal function of tissues and organs. The biochemical nature of the precursor protein forming the amyloid fibrils differs in the different clinical conditions such as chronic inflammatory infectious or non-infectious diseases, malignancies, hereditary diseases and other less common disorders. Identification of the type of amyloidosis is important to assess clinical management, prognosis and treatment. Amyloid fibril protein nomenclature “2010 recommendations of the nomenclature commitee of the International Society of Amyloidosis“ was reported and 27 human fibril proteins were described. In current nomenclature, a prefix “A” shows amyloid, followed by an abbreviation orginated from the name of the precursor protein (for example, AL addresses amyloid derived from immunglobulin light chain, AH shows amyloid derived from immunglobulin heavy chain, AA indicates amyloid derived from serum amyloid A (SAA) protein, Aß2M shows amyloid orginated from ß2 microglobulin, ATTR describes amyloid derived from transthretin, and others). The amyloidoses can be classified according to localized or systemic deposits along with its biochemical nature (2). Localised amyloid depositions usually lead to mechanical interference and generally are considered to be benign. Alzheimer’s disease is the only form of localized amyloid fibril deposition which often leads to serious disorder. Systemic amyloid forms include mainly immunoglobulin light chain (AL) amyloidosis, secondary, reactive (AA amyloidosis), hereditary familial form (for example, ATTR amyloidosis) and dialysis-related (A┚2M) amyloidosis (3,4). AA, AL and ATTR amyloidosis involve more than 90% of systemic amyloidosis (5). AL amyloidosis is the most common form of systemic amyloidosis in western world. The ratio AL/AA amyloidosis appears 2/1 in the Netherlands (6). A retrospective study from