These have been described as endemic in Sweden, Portugal or Japan. More recent studies provided evidence for the presence of hereditary amyloidotic neuropathies amongst the German population and that they are currently underdiagnosed. 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. 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. By limiting the study population to patients with PNP of unknown etiology it should be possible to gain evidence for the prevalence of the disease in Germany by investigating fewer patients.