Amyloidosis

Amyloidosis refers to a variety of conditions in which amyloid, an abnormal proteinaceous substance formed from misfolding of proteins is deposited between cells of various tissues and organs of the body. The symptoms and clinical findings of amyloidosis vary based on the quantity of deposits and the organs affected.

Amyloid

Amyloid is a fibrillar protein and by electron microscopy it is seen to be composed of nonbranching filaments of indefinite length and diameter of 8 to 10nm. On x-ray crystallography and infrared spectroscopy amyloid proteins exhibit a characteristic beta pleated sheet structure which is responsible for the distinctive staining and apple green-colored birefringence in polarized light with Congo red stain.

Classification

The modern classification of amyloid disease uses an abbreviation of the protein that makes up the majority of deposits, prefixed with the letter A for amyloid.
Major protein Precursor protein Description
AL amyloid light chain Contains immunoglobulin light-chains (λ,κ) derived from plasma cells
AA amyloid associated Non-immunoglobulin protein made in the liver
β amyloid Found in cerebral plaques deposited in Alzheimer disease
ATTR Transthyretin A mutant form of a normal serum protein that is deposited in the genetically determined familial amyloid polyneuropathies
Aβ2 m β2 microglobulin β2m is a normal serum protein, part of major histocompatibility complex (MHC) Class 1 molecules and is the major protein in haemodialysis associated amyloidosis

Clinical findings

Amyloidosis can be present without any manifestations or may cause serious illness depending on the quantity of deposits and the organs affected. Early manifestations of the disease are often vague and may include weakness, syncope, weight loss or lack of appetite. Specific findings appear later and relate to the pattern of organ involvement. Kidneys, spleen, liver, heart, peripheral nerves, skin, tongue and bowels are the major organs that are often involved.
Amyloidosis of the kidney is the most common and most serious form of the disease. Renal involvement leads to nephrotic syndrome, which is characterized by severe loss of protein in the urine and swelling of the face and extremities.



about                    contact us              disclaimer             faqs                    privacy           LifeHugger © 2008-2017