Beside the frequent genetic etiologies in PNP (pmp22, MFN2) one cause of a genetic polyneuropathy may be a hereditary amyloidosis. These have been described as endemic in Sweden, Portugal or Japan. The most common form of the hereditary familial amyloidotic neuropathy (FAP) is the Transthyretin-related FAP, however two other amyloidogenic proteins have been described: Apolipoprotein A-I and Gelsolin (Ando et al., 2005; Adams et al., 2010). This study focuses on TTR-FAP (OMIM: #105210, OMIM: *176300), whose prevalence shall be determined in a cohort of 500 patients with polyneuropathy of unknown etiology. The TTR-FAP is an autosomal dominant disease, the exact prevalence of which is unknown but estimated to be around 1:100,000 to 1:1,000,000 in the normal population (Orphanet, ORPHA 85447). While the diagnosis of the amyloidotic neuropathy can be conducted histologically, a molecular genetic approach is necessary to diagnose TTR-FAP. Even though more than 100 point mutations are known to cause the disease, the most common amino acid change is V30M.