Genetic disease and amyloid

Amyloid results from the deposition, principally in connective tissue, of polymers that are for the most part incompletely digested precursor proteins. In man the resulting deposits are very resistant to resorption or digestion: their relentless accumulation often causes death by interfering with the function of vital organs such as the kidneys, heart, and gut. There are three definitive methods for recognising amyloid. (1) The dye congo red is bound more strongly by amyloid than by human albumin (Bennhold, 1922). It then exhibits a green bire-fringence in polarised light (Missmahl, 1957). (2) Electron microscopy reveals a characteristic fibrillar structure (Cohen and Calkins, 1959) that is non-branching, of variable length, and 8-15 nm wide