Genetic studies of familial amyloid polyneuropathy in the Arao district of Japan

The predominant amyloid fibril proteins isolated from kidneys of four patients with familial amyloid polyneuropathy (FAP) from three genealogically independent families in the Arao district of Japan have been analysed for the primary structure. Irrespective of the patient or the family, the major protein isolated consisted of some components of a prealbumin variant, in which an amino acid substitution of methionine for valine occurred at position 30, with a heterogenous N-terminus caused by some degradation of N-terminal amino acids in the prealbumin subunit. It is likely that this prealbumin variant is concerned with the process of this hereditary disease, rather than being a genetic polymorphism of prealbumin. Further, we conclude that the FAP families of the Arao focus may have a common ancestor.