Amyloidosis (am-uh-loi-DO-sis) is a rare disease that occurs when a substance called amyloid builds up in your organs. Amyloid is an abnormal protein that is produced in your bone marrow and can be deposited in any tissue or organ. Amyloidosis frequently affects the heart, kidneys, liver, spleen, nervous system and digestive tract.

https://newsnetwork.mayoclinic.org/discussion/what-is-amyloidosis-and-10-signs-you-might-have-it/