Hereditary and acquired amyloid neuropathies

Amyloid neuropathies occur in a context of hereditary (FAP) or acquired amy loidosis. They present usually as severe and progressive polyneuropathy and carry a poor prognosis. Most FAP are associated with endoneurial deposits of variant transthyretin (TTR) with substitution of one aminoacid and are s econdary to a point mutation of the TTR gene. Portugal is the main endemic area of TTR-FAP, secondary to point mutation of exon 2. However, around the world, 50 other TTR gene mutations have been recently reported, each one i n few families. Genetic studies are useful for diagnosis of FAP in patients with a positive family history and for identification of the cause of seem ingly sporadic cases. TTR gene analysis is also useful for genetic counsell ing including antenatal diagnosis in variants with early onset. Gelsolin-FA P are the second variety and present as a benign cranial and sensory polyne uropathy and affect essentially Finnish patients. Acquired amyloid neuropat hy concerns only immunoglobulin light chain amyloidosis (AL) and are freque ntly associated with renal manifestations and monoclonal protein in serum o r urine. Specific treatment of amyloid polyneuropathy varies with the varie ty of amyloidosis including liver transplantation in TTR-FAP, at the onset of the disease or chemotherapy for immunoglobulin light chain amyloidosis.