Familial amyloid polyneuropathy (FAP) is a genetic disease leading to the production of a variant transthyretin (TTR) or a beta variant β2-microglobulin.
Peripheral nerve amyloidosis is the cardinal feature of familial amyloid polyneuropathy (FAP) but can also be seen in primary light chain (AL) amyloidosis and dialysis (beta 2-microglobulin) related amyloidosis.