Transthyretin (TTR) originally called prealbumin is a serum and cerebrospinal fluid carrier of the thyroid hormone thyroxine (T4) and retinol. Prealbumin concentrations are disproportionately high in human ventricular cerebrospinal fluid (CSF). Over 80 different disease-causing mutations in prealbumin have been reported. TTR is known to be associated with the amyloid diseases senile systemic amyloidosis (SSA), familial amyloid polyneuropathy (FAP), and familial amyloid cardiomyopathy (FAC).