TTR and Familial transthyretin-related amyloidosis: However, a recent paper provides another clue, reporting that the TH carrier protein transthyretin (TTR), which is the major T4 carrier in CSF and is expressed mainly in the choroid plexus and leptomeningeal epithelium [135,136,137], seems to be present in Corpora amylacea in hereditary transthyretin amyloidosis [138].