How are the different types of amyloidosis classified?
Amyloidosis is classified according to the main protein that causes that particular type of amyloidosis. The name of each type of amyloid protein consists of “A” for amyloid followed by an abbreviation for the protein that makes up the amyloid deposits. For example, in AL amyloidosis the A stands for amyloid and L for the type of fibril protein, light chain.
Amyloidosis was previously classified as “primary” (occurring on their own) or “secondary” (occurring secondary to another underlying condition), but this terminology was confusing and is no longer used.
The Most Common Types of Amyloidosis are:
AL amyloidosis is formed from misfolded immunoglobulin light chains that are produced by plasma cells in the bone marrow. Usually these plasma cells are benign, but occasionally the amyloid forming light chain protein can be produced by a cancer of plasma cells called Multiple Myeloma. About 15% of patients with Multiple Myeloma will also develop AL amyloidosis. Patients with AL amyloidosis rarely go on to develop myeloma.
AA amyloidosis occurs when the Serum Amyloid A (SAA) protein increases in some people substantially in response to a long-term inflammatory disorder such as rheumatoid arthritis.
Hereditary amyloidosis occurs when a gene mutation is inherited, leading to the life-long production of an abnormal or variant protein. The most common types of hereditary amyloidosis are ATTRv (transthyretin gene mutation) and AFib (fibrinogen-alpha chain gene mutation).
Wild type ATTRwt, previously known as Senile Amyloidosis, occurs when normal or “wild type” transthyretin amyloid deposits in the heart. This is NOT an inherited disease.
Localised Amyloidosis occurs when the the amyloid protein is produced and deposited in one part of the body only.
NB: Alzheimers disease and Cerebral Amyloid Angiopathy (CAA) are not considered to be forms of amyloidosis. These diseases are therefore not treated in the Australian Amyloidosis Centres and not mentioned on this web site.
Click on the different types of amyloidosis for more information.