Last edited 05/2019 and last reviewed 05/2019

Different proteins can be deposited as amyloid in various tissues

  • deposition can be restricted to one specific site (such as pancreas, brain, larynx) (localized amyloidosis) or can be found throughout the body (systemic amyloidosis)
    • are a many types of localized amyloidosis including cerebral endocrine, and cutaneous amyloidosis
      • only the name amyloid is identical, but the localised types of amyloid mentioned above are completely different because of different precursor proteins

  • five main types of systemic amyloidosis are:
    • systemic forms of amyloid that should be distinguished from each other (four acquired and one hereditary) are AA, AL, Aß2M, and two ATTR types:
      • acquired AA amyloidosis
        • caused by chronic inflammation
        • serum amyloid A protein (SAA), an acute phase reactant, is the precursor protein of this type
        • proteinuria and loss of renal function are the most prominent clinical characteristics

      • acquired AL amyloidosis
        • caused by a plasma cell dyscrasia
        • precursor protein of this type is a kappa or lambda immunoglobulin light chain
        • clinical characteristics of this type are very diverse, such as cardiomyopathy, hepatomegaly, nephrotic syndrome, severe diarrhoea, carpal tunnel syndrome, and neuropathy (peripheral as well as autonomic neuropathy)

      • acquired Aß2M amyloidosis
        • caused by chronic dialysis because of complete renal failure
        • precursor protein of this type is ß2-microglobulin because high serum levels are the result of the impossibility to excrete this protein
        • clinical characteristics of this type are carpal tunnel syndrome and joint problems (shoulders, wrists, fingers, hips, vertebral column, etc.)

      • acquired ATTR amyloidosis
        • found at older age (especially older than 80 years)
        • the normal wild type precursor protein transthyretin (TTR) is the characteristic protein
        • clinically characterised by a slowly progressive cardiomyopathy

      • hereditary ATTR amyloidosis
        • caused by more than 80 autosomal dominant hereditary point mutations of the precursor protein transthyretin (TTR)
        • clinical characteristics of this type are peripheral and autonomic neuropathy, but also cardiac, renal, and ocular involvement can be seen