Organ Involvement in Amyloidosis
The name amyloidosis is a collective term for a group of relatively rare and complicated disorders in which abnormal proteins, which have in common an abnormal chemical structure called a beta-pleated sheet, form abnormal amyloid fibrils. These fibrils are relatively insoluble and cannot be broken down easily by the body. They progressively accumulate and deposit within the body’s organs and tissues (except the brain) which without treatment, can lead to organ failure and death.
Most types of amyloidosis are systemic, meaning that the amyloid protein can be deposited in any of the organs and tissues of the body with the exception of the brain.
Organ involvement will vary between the types of amyloidosis and from person to person.
Which organs are involved and to what degree is very important and will influence treatment decisions.
The most critical and fatal manifestation of systemic amyloidosis is cardiac involvement.
Classification and Nomenclature
The classification of amyloid and amyloidosis is based on the amyloid fibril proteins, followed by a designation of the fibril protein precursor.
For example: in AL amyloidosis the A stands for amyloid and the L for Light chain, the precursor.
The most common types of amyloidosis are:
- AL amyloidosis. Light chain amyloidosis caused by a bone marrow disorder.
- AA amyloidosis. Occurs when the (Serum amyloid A) SAA protein increases substantially in response to a long-term inflammatory disorder such as rheumatoid arthritis.
- Hereditary amyloidosis, including ATTRv occurs when a gene mutation is inherited, leading to the life-long production of an abnormal protein
- Wild type ATTR amyloidosis. Occurs when too much “wild type” transthyretin is produced. This is NOT an inherited disease.
- Localised Amyloidosis. Occurs when the amyloid protein is produced and deposited in one part of the body only.
Amyloidosis and Major Organ Involvement
|Amyloid type||Nature of amyloid forming protein||Other names||Major organs involved|
|AL||Immunoglobulin light chain||Primary systemic amyloidosis
|AA||Amyloid A protein||Secondary amyloidosis||Kidney
|ATTRv||Transthyretin||Familial amyloidotic polyneuropathy||Nervous system
|AFib||Fibrinigin alpha chain||Kidney|
The goals of treatment in all types of amyloidosis are:
- To stop or slow the production of the amyloid protein.
- To tailor treatment to the individual patient.
- To preserve and support the affected organs and tissues.
- To improve quality of life by offering good symptom control and psychosocial support.
Knowledge of which organs and tissues are affected by the amyloid and to what degree, is extremely important when treatment decisions are being made. Amyloid in the heart remains a major concern.
Use the links below to learn more about each type.