Transthyretin (TTR) is also known as prealbumin. It is mapped to chromosome region 18q11.2-q12.1. This gene encodes a carrier protein responsible for the transport of thyroid hormones and retinol. The protein consists of a tetramer of identical subunits. Due to increased stability of the tetramer form of this encoded protein in mouse, compared to the human protein, this gene product has a reduced tendency to form amyloid fibrils. In humans, this protein binds beta-amyloid preventing its aggregation and providing a neuroprotective role in Alzheimer's disease.