Familial amyloid polyneuropathy (FAP) is a most often length-dependent axonal neuropathy, often part of a multisystem disorder also affecting other organs, such as cardiac, gastrointestinal, genitourinary, renal, meningeal and eye tissue. It is most frequently the result of a mutation in the TTR gene, most commonly a p.Val50Met mutation. TTR-FAP is a rare autosomal dominant heritable disabling, heterogeneous disease in which early diagnosis is of pivotal importance when attempting treatment. This paper discusses the course of four Belgian FAP patients with different TTR mutations (p.Val48Met; p.Val52Ala; p.Ala59Val; p.Val50Met). We also review the diagnosis and differential diagnosis of TTR-FAP, diagnostic studies, follow-up, its current treatment and those in development, prognosis and the importance of genetic counseling. At first, TTR-FAP is often misdiagnosed as a chronic inflammatory demyelinating polyneuropathy or chronic idiopathic axonal polyneuropathy. Genetic testing is obligatory to confirm the diagnosis of TTR-FAP, except in familial cases. Biopsy samples are an asset in diagnosing TTR-FAP but can be falsely negative. At the moment, tafamidis meglumine is considered as first-line treatment in stage I neurological disease. Patients eligible for liver transplantation should be carefully selected when first-line therapy fails.
Keywords: Genetic testing; Liver transplantation; Tafamidis meglumine; Transthyretin familial amyloid polyneuropathy.