Familial amyloid polyneuropathy (FAP) is a hereditary form of amyloidosis most commonly caused by mutations in transthyretin (TTR) and was initially reported from endemic foci in Portugal, Japan and Sweden. However, development in gene diagnostic techniques revealed that FAP patients are more widely distributed and have varied phenotypes even in the same mutation.1 ,2 For example, Japanese patients who have early onset FAP with amyloidogenic TTR Val30Met mutation (FAP amyloidogenic transthyretin (ATTR) Val30Met) in endemic foci in Kumamoto and Nagano prefectures exhibit clinicopathological features distinct from those of late-onset FAP ATTR Val30Met patients in non-endemic areas.2 Because late-onset FAP ATTR Val30Met in non-endemic areas is now more prevalent than expected, this entity may represent …