FAP Neuropathy and Emerging Treatments

Transthyretin familial amyloid polyneuropathy (TTR-FAP) classically presents as a length dependent small fiber polyneuropathy in endemic countries like Portugal. In nonendemic countries, it may mimic a variety of chronic polyneuropathies, with several phenotypes: ataxic, upper limb onset neuropathy, or motor. In these cases, there is usually a late onset and no positive family history. TTR gene sequencing appears the most pertinent first-line test for diagnosis. Cardiac involvement of various severities is common in FAP. Liver transplantation remains the standard antiamyloid therapy with better results in Val30Met TTR-FAP of early onset. Antiamyloid medication has been developed. (1) TTR stabilizers: Tafamidis was the first drug approved in Europe in stage 1 (walking unaided) TTR-FAP to slow progression of the disease; diflunisal has been assessed in a phase 3 clinical trial; (2) TTR gene silencing is a new strategy to inhibit production of both mutant and nonmutant TTR with antisense oligonucleotides or SiRNA (2 ongoing phase 3 clinical trials).