TTR and poikiloderma with neutropenia: In this disease, TTR, the serum transport protein for thyroxine and vitamin A, misfolds and is deposited as amyloid in peripheral nerves, causing polyneuropathy (ATTR-PN) in the heart, causing cardiomyopathy (ATTR-CM), and sometimes in other organs like the kidney, digestive tract, and eyes, causing various organ dysfunctions.