TTR and Abnormal autonomic nervous system physiology: Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is an autosomal dominant disorder caused by TTR gene mutation and characterized by extracellular deposition of TTR amyloid fibrils in the peripheral nerve, heart, and other organs, leading to sensory-motor axonal polyneuropathy, cardiomyopathy, autonomic dysfunction, nephrotic syndrome, and vitreous opacities (1, 2).