What is it Amyloidosis?
This non-contagious disease is characterized by the formation of protein deposits that alter the normal functioning of organs. It most often evolves into a severe form and can affect all organs. The total number of people affected by this rare disease in France is not precisely known, but it is estimated that it affects 1 in 100,000 people. (1) About 500 new cases of AL amyloidosis, the least rare form of the disease, are diagnosed each year in France.
Amyloidosis deposits can potentially appear in almost every tissue and organ of the body. Amyloidosis most often evolves into a severe form by gradually destroying the affected organs: the kidney, heart, digestive tract and liver are the organs most often affected. But amyloidosis can also affect the bones, joints, skin, eyes, tongue…
Therefore, the range of symptoms is very wide: malaise and shortness of breath when the heart is affected, edema of the legs in the case of the kidney, drop in muscle tone when peripheral nerves are affected, diarrhea/constipation and obstruction in the case of the digestive tract, etc. Acute symptoms such as shortness of breath, diarrhea and bleeding should raise the alarm and lead to a screening for amyloidosis.
The origins of the disease
Amyloidosis is caused by a change in the molecular structure of a protein, making it insoluble in the body. The protein then forms molecular deposits: the amyloid substance. It is more accurate to speak of amyloidosis than of amyloidosis, because although this disease has the same cause, its expressions are very diverse. Indeed, about twenty proteins are responsible for as many specific forms. However, three types of amyloidosis predominate: AL (immunoglobulinic), AA (inflammatory), and ATTR (transthyretin).
- AL amyloidosis results from the multiplication of certain white blood cells (plasma cells). They produce antibodies (immunoglobulins) that aggregate and create deposits.
- AA amyloidosis occurs when chronic inflammation leads to a high production of SAA proteins that will form amyloidosis in the tissues.
- The transthyretin protein is involved in ATTR amyloidosis. This form of the disease is genetic. An affected parent has a 50% chance of passing the mutation on to their child.
Amyloidosis is not contagious. Epidemiological data clearly indicate that the risk increases with age (amyloidosis is often diagnosed around 60-70 years old). People with infectious or inflammatory diseases, as well as those who have undergone long dialysis, are more vulnerable. Some forms of amyloidosis, such as ATTR amyloidosis, are linked to an inherited genetic mutation, so families in which one or more members have been affected need to be monitored.
Prevention and treatment
To date, there is no prevention against amyloidosis. The treatments all consist of reducing the production of the toxic protein that is deposited and aggregated in the tissues, but they vary according to the type of amyloidosis:
- by chemotherapy in the case of AL amyloidosis. The drugs used in its treatment have shown “real efficacy”, says the National Society of Internal Medicine (SNFMI), while pointing out that the cardiac damage remains serious.
- In the case of AA amyloidosis, it is possible to treat the disease with powerful anti-inflammatory drugs to fight the inflammation that caused the disease.
- For ATTR amyloidosis, a transplant may be required to replace a liver colonized by the toxic protein.