Amyloidosis is a disorder in which abnormal proteins build up in tissues and organs. The cause of primary amyloidosis is unknown. The condition is related to abnormal and excess production of antibodies by a type of immune cell called plasma cells. Clumps of abnormal proteins build up in certain organs. This reduces their ability to work correctly. Symptoms depend on the organs affected. This disease can affect the tongue, intestines, skeletal and smooth muscles, nerves, skin, ligaments, heart, liver, spleen, and kidneys. Symptoms include: abnormal heart rhythm, fatigue, numbness of hands or feet, shortness of breath, hoarseness or changing voice, and joint pain.