TTR and neurodegenerative disease: TTR is synthesized mainly bythe liver and the choroid plexus, and to some extent in the pancreasand the eye.1 It is an important proteinfor metabolic homeostasis and has also been suggested to functionas a molecular chaperone to prevent aggregation of proteins associatedwith neurodegenerative diseases.2 TTR circulatesin human plasma and cerebrospinal fluid and functions as a transportprotein of the metabolic hormone thyroxine (T4) and retinol (VitaminA) through complex formation with retinol-binding protein (RBP).1 T4 binds directly to TTR.