What is amyloidosis?
Amyloidosis is the general term given to a relatively rare and serious group of disorders in which an abnormal protein known as amyloid is produced. Amyloid (the word means “starch like”) is an unusually stable material which has a unique chemical structure formed when certain proteins fold in an abnormal way.
These protein fibrils progressively deposit and accumulate in organs and tissues of the body, disrupting normal function. Without treatment this eventually leads to organ damage and failure.
Amyloid medicine is constantly evolving. As medical science advances, new types of amyloid continue to be discovered as does new effective directed therapies. At this time there are over 30 types of proteins giving rise to amyloidosis.
The nomenclature system for the amyloid fibril protein is based on the fibril precursor protein so the nomenclature system for the amyloid fibril system always starts with an “A”, signifying amyloid, followed by letters which are an abbreviated form of the precursor/constituent protein name e.g.
- Immunoglobulin Light chain amyloid is called AL
- Transthyretin amyloid is called ATTR.
The correct term for transthyretin amyloidosis is then ATTR amyloidosis and the correct term for light chain amyloidosis is AL amyloidosis
Sometimes the same precursor protein can form amyloid via both acquired and inherited mechanisms. This is most relevant for transthyretin amyloidosis. To distinguish between these two groups;
- “wt” denotes amyloid derived from wild type protein=physiologic protein e.g. ATTRwt
- “v” denotes a variant protein created by an amyloidogenic gene e.g. ATTRv signifies transthyretin amyloidosis caused by any inherited amyloidogenic transthyretin gene mutation
