Familial amyloid polyneuropathy (FAP) is most commonly associated with variant plasma transthyretin, although it has also been described in association with mutant apolipoprotein A-1 and gelsolin. There are now approximately 26 point mutations in the transthyretin gene associated with FAP. Because of the overlapping clinical phenotypes described with these mutations, it is now more appropriate to classify the various forms of FAP according to the underlying genetic defect rather than on clinical grounds. Many questions concerning the amyloidogenic nature of transthyretin and the variability of organ involvement depending on the underlying mutation remain unanswered. The recent use of liver transplantation for treatment appears to be promising.