Transthyretin (TTR) is a circulating and abundant tetramer, which functions as a carrier protein of thyroid hormone and retinol binding protein. It is primarily produced in the liver, but also in the brain and eye. Mutations in the TTR gene cause the protein to dissociate into monomers that after misfolding assemble into amyloid fibrils deposits in a variety of organs. TTR is also the only gene known to be associated with familial TTR amyloidosis. The diseases that originate from mutations in the TTR gene include amyloidotic polyneuropathy, euthyroid hyperthyroxinaemia, amyloidotic vitreous opacities, cardiomyopathy, oculoleptomeningeal amyloidosis, meningocerebrovascular amyloidosis, carpal tunnel syndrome, etc.
