Amyloidosis is a group of diseases in which one or more organ systems accumulate deposits of abnormal proteins, called amyloid proteins. These abnormal proteins originate from cells in the bone marrow that makes antibodies or proteins that protect people from infection and disease.When a person has amyloidosis, bone marrow produces faulty antibodies that build up in the bloodstream and tissues. Once enough amyloid proteins build up in one or more organs, organs begin to malfunction.
Amyloidosis affects the heart, kidneys, nervous system, gastrointestinal tract including the tongue, stomach small intestines and colon, and many other areas.
Fortunately, amyloidosis is rare, affecting about eight per 1 million people annually. The majority of those affected are over 40 years of age and 60 percent are male, although the condition can affect anyone. The cause of the disease remains unknown.
People may be at increased risk if they have a chronic infectious or inflammatory disease, a family history of the disease or multiple myeloma — a form of bone marrow cancer. About 10 percent of people who have multiple myeloma develop amyloidosis. Patients requiring kidney dialysis — particularly for more than five years — also may be at increased risk for amyloidosis if their failing kidneys are unable to remove excess proteins from the blood, allowing abnormal proteins to build up and deposit in surrounding tissues.
There are three main types of amyloidosis:
Primary Amyloidosis — This is a plasma cell disorder originating in the bone marrow. It is the most common type of amyloidosis in North America, affecting 2,000 people each year. This condition, which is usually treated with chemotherapy, is not considered to be a type of cancer. However, it may be associated with multiple myeloma, which is a type of bone cancer. The severity of the illness often depends on the number and extent of organ involvement.
Secondary Amyloidosis — This condition is caused by a chronic infection or inflammatory disease such as rheumatoid arthritis, familial Mediterranean fever (an intestinal disorder), osteomyelitis or granulomatous ileitis. The deposits in this type of the disease are made up of a protein called the AA protein. Medical or surgical treatment of the underlying chronic infection or inflammatory disease can slow or stop the progression of this type of amyloid.
Familial (or Hereditary) Amyloidosis — This is the only type of amyloidosis that is inherited. It is a rare form of the disease affecting families of nearly every ethnic background. The deposits in this type are most commonly made up of the transthyretin protein produced in the liver. Amyloidosis results from a mutation in this protein.
Symptoms of amyloidosis depend on the organs it affects. The wide range of symptoms often makes amyloidosis difficult to diagnose. Some people may not experience any symptoms and others may have many symptoms. Frequently described symptoms include: