Transthyretin Amyloidosis (ATTR) is a rare, progressive, and fatal genetic disorder caused by the buildup of abnormal proteins in the body's organs and tissues. The abnormal proteins, called amyloid, are made up of a protein called transthyretin (TTR). As the amyloid builds up, it can damage organs and tissues, leading to a variety of symptoms. Symptoms of ATTR can include peripheral neuropathy, autonomic neuropathy, cardiomyopathy, and carpal tunnel syndrome. Treatment options for ATTR include medications, lifestyle changes, and organ transplantation.