There are at least six known types of amyloidosis, a relatively rare disease characterized by an excessive build up of a particular, sometimes abnormal protein: amyloid. Although amyloidosis cannot be cured, there are several types of treatment available for the different types that can help control symptoms and improve quality of life. The type of amyloid protein present is a key factor in identifying the type of amyloidosis, and thus, the cause of the disease(s). Here’s a look at the causes of the more common types of amyloidosis.
Also called immunoglobulin light chain amyloidosis, AL amyloidosis is most common in the 50 to 80 year old population, although it may occur in early adulthood too. According to the Amyloidosis Foundation, males account for nearly two-thirds of the affected cases. A bone marrow disease is the originator of AL amyloidosis. Bone marrow, located within each of the bones of the human body, is responsible for the production of plasma cells, which are antibodies that protect against infections.
Plasma cells then produce immunoglobulins, the proteins that act as antibodies. When AL is present, the immunoglobulin is abnormal. The chains of protein are “folded” incorrectly in their makeup and then sent all around the body, where they can build up in tissues, organs, causing damage and getting in the way of the affected structures’ normal function. Several spots may be afflicted at once, and every person’s AL will develop differently.
AA amyloidosis appears as a response to other chronic diseases when the liver creates large amounts of “serum amyloid A protein (SAA).” Although this is perfectly natural, prolonged inflammation may cause AA protein in some patients to break apart from the SAA protein; the AA protein then moves itself around the body, particularly in the kidneys, as AA amyloid, instead of breaking down completely like normal. According to the Amyloidosis Foundation, the diseases most likely to create this reaction include:
- Rheumatologic diseases, such as rheumatoid arthritis
- Gastrointestinal inflammatory diseases, such as Crohn’s disease
- Hematologic malignancies, such as renal cell carcinoma
- Chronic infectious diseases, such as AIDS or tuberculosis
- Hereditary disorders, such as Familial Mediterranean Fever (FMF)
Hereditary amyloidosis is a disease caused by inheriting a mutated gene that causes production of an abnormally formed amyloid protein. Like AL amyloidosis, the amyloid protein is folded incorrectly and then spreads throughout the body where it builds up, although problems are generally not seen until the patient is an adult. There are multiple types of hereditary amyloidosis; again, each case is different, which means symptoms may vary from nonexistent to moderate to extremely severe, especially in the heart, kidneys, liver, and nerves. It is more common among African-Americans.
Wild-Type amyloidosis is most common among men over the age of 80 and occurs frequently with carpal tunnel syndrome. The Amyloidosis Foundation reports that “the misfolding and depositing amyloid protein comes from transthyretin protein without a genetic mutation, referred to as “wild-type” because it is the natural form of this protein.” The build up is especially dangerous to the heart but often overlooked because of the frequency of heart problems in older men.