Amyloidosis is a group of rare but serious diseases caused by deposits of abnormal protein, called amyloid, in tissues and organs throughout the body.
It is diagnosed in 1-5 in every 100,000 people in the UK every year, and is more common in older people.
Proteins begin as a string of amino acids which then fold themselves into a three-dimensional shape. This ‘protein folding’ allows them to perform useful functions within our cells.
Amyloid proteins are abnormally folded, which causes them to build up in tissues and organs, leading to organ failure. A particular type of amyloid protein also occurs in the brain of people with Alzheimer’s disease.
If amyloid is deposited in only one part of the body, it’s known as localised amyloidosis and is usually less serious than the systemic (widespread) forms. For example, amyloidosis can affect the skin only, causing discolouration and/or an itchy rash.
However, most cases are systemic – in other words, the amyloid deposits are widespread and can potentially affect many tissues and organs throughout the body. Systemic amyloidosis is often very serious: it commonly damages the heart, kidneys, gut and nerves, causing progressive organ failure.
There are more than 20 different proteins that can misfold and form amyloid, which is why there are many different types of systemic amyloidosis.
This page will focus on the most common type in the UK: primary (AL) amyloidosis.
The less common types of amyloidosis are explained briefly in the box on this page.
Symptoms of AL amyloidosis
In AL amyloidosis, amyloid can build up gradually in organs for many years before it causes symptoms. The symptoms you have will depend on which organs are affected.
For example, if amyloid is deposited in the kidneys, it may cause chronic kidney failure. Symptoms of kidney failure include fluid retention, tiredness, weakness and loss of appetite.
Amyloid deposited in the heart can cause it to become enlarged and impair its ability to pump blood efficiently around the body. This may result in heart failure, which causes breathlessness and fluid retention.
AL amyloidosis can potentially cause any of the following symptoms:
- weight loss
- fluid retention (oedema)
- shortness of breath
- numbness or a tingling feeling in the hands and feet
- carpal tunnel syndrome (compression of the nerve in your wrist)
- blood spots on the skin
- an enlarged tongue – sometimes with blood spots, plaques and blisters
Causes of AL amyloidosis
AL amyloidosis is caused by the misfolding and build-up of a protein called light chain, which is produced by abnormal white blood cells in the bone marrow.
The abnormal bone marrow cells are usually benign (non-cancerous), but are malignant in a proportion of cases (in multiple myeloma, cancer of the bone marrow). AL amyloidosis is sometimes referred to as ‘light chain amyloidosis’.
The abnormal light chain protein is typically deposited in the heart, kidneys, nerves or gut, or a combination of these.
How it is diagnosed
Diagnosis of AL amyloidosis can be very challenging, since the symptoms are often very general.
The diagnosis can be confirmed by taking a biopsy (tissue sample) of the affected part of the body, and examining this under a microscope in the laboratory, using special stains for amyloid proteins.
The type of biopsy will depend on which organs are affected. In some patients in whom amyloidosis is suspected, a biopsy of tummy fat or a biopsy from the gut (taken during an endoscopy) may give a positive result.
Specialist diagnostic scanning methods are also available at the NHS National Amyloidosis Centre at the Royal Free Hospital in London.
How it is treated
Chemotherapy drugs can inhibit the abnormal bone marrow cells, and hence production of abnormal protein. This can result in a gradual reduction of the amount of amyloid in the body and prevent organ damage.
Some patients with kidney failure may be suitable to receive a kidney transplant, although the underlying bone marrow disorder will need to be suppressed by chemotherapy to prevent build-up of amyloid in the new kidney.
- Published Date
- 2014-04-03 16:07:33Z
- Last Review Date
- 2012-10-03 00:00:00Z
- Next Review Date
- 2014-10-03 00:00:00Z
- Chronic renal failure