Hereditary transthyretin amyloidosis (hATTR) is a rare, systemic disease passed down through families. Caused by genetic mutations in the transthyretin (TTR) gene, it leads to a buildup of abnormal proteins called amyloid in one or more organs and tissues, impairing their function. Left untreated, hATTR can cause life-threatening complications. Early diagnosis and treatment are critical to prevent or delay progression of hATTR.