Amyloid (pronounced am'-i-loyd) is an abnormal protein that may be deposited in any of your body's tissues or organs. This abnormal protein comes from cells in your bone marrow. The disease known as amyloidosis (pronounced am-i-loy-do'-sis) results when enough amyloid protein builds up in one or more organs to cause the organ(s) to malfunction. The heart, kidneys, nervous system and gastro-intestinal tract are most often affected. From the Mayo Clinic Rochester