- Acroparaesthesia The currently available therapeutic approaches are either liver transplantation (as the liver mainly produces transthyretin this is a feasible approach) or as of more recently also a TTR-tetramer stabilizing agent (Tafamidis). Tafamidis (Vyndaqel®) gained the European approval under "exceptional circumstances"in November 2011 for treating FAP in adults with a symptomatic polyneuropathy.In light of the potential therapy of this very rare disease this study aims to determine the prevalence of TTR-FAP in a selected, clinical subpopulation. New methods, like mass-spectrometry give a good chance to characterize specific metabolic alterations in the blood (plasma) of affected patients that allow diagnosing in the future the disease earlier, with a higher sensitivity and specificity. Therefore it is the goal of the study to identify and validate a new biochemical marker from the plasma of the affected patients helping to benefit other patients by an early diagnose and thereby with an earlier treatment.