Amyloid light-chain (AL) amyloidosis, also known as primary amyloidosis, is the most common form of systemic amyloidosis in the US. The disease is caused when a person's

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

-producing cells do not function properly and produce abnormal protein fibers made of components of antibodies called light chains. These light chains come together to form amyloid deposits which can cause serious damage to different organs. Abnormal light chains in urine are sometimes referred to as "

Bence Jones protein Bence Jones protein is a monoclonal globulin protein or immunoglobulin light chain found in the urine, with a molecular weight of 22–24 kDa. Detection of Bence Jones protein may be suggestive of multiple myeloma or Waldenström's macroglobuli ...

Signs and symptoms

AL amyloidosis can affect a wide range of organs, and consequently present with a range of symptoms. The kidneys are the most commonly affected organ in AL amyloidosis. Symptoms of kidney disease and

kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...

can include fluid retention, swelling, and shortness of breath. In addition to kidneys, AL amyloidosis may affect the heart, peripheral nervous system, gastrointestinal tract, blood, lungs and skin. Heart complications, which affect more than a third of AL patients, include heart failure and irregular heart beat. Other symptoms can include stroke, gastrointestinal disorders,

enlarged liver Hepatomegaly is the condition of having an enlarged liver. It is a non-specific medical sign having many causes, which can broadly be broken down into infection, hepatic tumours, or metabolic disorder. Often, hepatomegaly will present as an abdomi ...

, diminished spleen function, diminished function of the adrenal and other

endocrine gland Endocrine glands are ductless glands of the endocrine system that secrete their products, hormones, directly into the blood. The major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, ...

s, skin color change or growths, lung problems, bleeding and bruising problems, fatigue, and weight loss.

Causes

AL amyloidosis is caused by the deposition of abnormal antibody free light chains. The abnormal light chains are produced by monoclonal plasma cells, and, although AL amyloidosis can occur without diagnosis of another disorder, it is often associated with other plasma cell disorders, such as multiple myeloma and Waldenström's macroglobulinemia. About 10% to 15% of patients with multiple myeloma may develop overt AL amyloidosis.

Diagnosis

Both blood and the urine can be tested for the light chains, which may form amyloid deposits, causing disease. However, the diagnosis requires a sample of an affected organ. Other diagnosis can be tissue biopsy. Tissue biopsy tests a tissue sample to look for amyloid deposits. The tissue is stained with red dye, and under a microscopic examination, amyloid proteins can be detected if the tissue turns an apple-green color.

Treatment

The most effective treatment is autologous bone marrow transplants with stem cell rescues. However many patients are too weak to tolerate this approach. Other treatments can involve application of

chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...

similar to that used in multiple myeloma. A combination of

melphalan Melphalan, sold under the brand name Alkeran among others, is a chemotherapy medication used to treat multiple myeloma, ovarian cancer, melanoma, and AL amyloidosis. It is taken by mouth or by injection into a vein. Common side effects incl ...

and

dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...

has been found effective in those who are ineligible for stem cell transplantation, and a combination of

bortezomib Bortezomib, sold under the brand name Velcade among others, is an anti-cancer medication used to treat multiple myeloma and mantle cell lymphoma. This includes multiple myeloma in those who have and have not previously received treatment. It is ...

and dexamethasone is now in widespread clinical use.

Prognosis

Median survival for patients diagnosed with AL amyloidosis was 13 months in the early 1990s, but had improved to months a decade later.

Epidemiology

AL amyloidosis is a rare disease; only 1200 to 3200 new cases are reported each year in the United States. Two thirds of patients with AL amyloidosis are male and less than 5% of patients are under 40 years of age.

References

External links

{{Immunoproliferative immunoglobulin disorders Amyloidosis