Familial amyloid polyneuropathy in Taiwan: identification of transthyretin variant (Leu55-->Pro).

We report a family with familial amyloid polyneuropathy (FAP), showing an early-onset and a fatal outcome before age 30. Transthyretin (TTR) gene analysis showed one point mutation (T-->C change) in the second base of codon 55, and the corresponding amino acid substitution of proline (Pro) for leucine (Leu) was confirmed at the protein level. This is the first FAP family of Taiwanese origin demonstrating a causative gene abnormality, and FAP with TTR-Pro55 was considered to be more serious compared with other forms of FAP.