NORD gratefully acknowledges Vaishali Sanchorawala, MD, Director of Amyloidosis Center, Boston University School of Medicine and Boston Medical Center, for assistance in the preparation of this report.
Amyloidosis is a systemic disorder that is classified into several types. The different types of amyloidosis are classified as systemic or localized. AL (immunoglobulin light chain, historically known as primary) amyloidosis is the most common type of systemic amyloidosis. AL amyloidosis results from an abnormality (dyscrasia) of a type of white blood cell called plasma cells in the bone marrow, and is closely related to multiple myeloma. AA (historically known at secondary) amyloidosis is derived from the inflammatory protein serum amyloid A. AA amyloidosis occurs in association with chronic inflammatory disease such as the rheumatic diseases, familial Mediterranean fever, chronic inflammatory bowel disease, tuberculosis or empyema. Hereditary amyloidosis is a rare type of amyloidosis that is caused by an abnormal gene. There are several abnormal genes that can cause hereditary amyloidosis, but the most common type of hereditary amyloidosis is called ATTR and caused by mutations in the transthyretin (TTR) gene. Age related amyloidosis, in which the amyloid is derived from wild-type (normal) transthyretin, is a slowly progressive disease that affects the hearts of elderly men and is called ATTRwt amyloidosis. Amyloid deposits may occasionally occur in isolation without evidence of a systemic disease; isolated bladder or tracheal amyloidosis are the most common such presentations. Dialysis-related beta2-microglobulin amyloidosis is a type of systemic amyloidosis that can occur in individuals who have experienced long-term kidney dialysis to remove accumulated impurities or wastes in the blood by mechanical filtration. This form of amyloidosis, also known as ABM2 (amyloid associated with the beta-2m protein), is associated with the aggregation of beta2-microglobulin, a type of amyloid protein that is cleared in the normally-functioning kidney. Dialysis-related beta2-microglobulin amyloidosis occurs in patients with near end-stage renal disease. It does not affect individuals with normal or mildly reduced renal function or patients with a functioning renal transplant.
Amyloidosis is usually a multisystem disease resulting in a wide spectrum of clinical presentations. Consequently, a patient may present to, or be referred to, one of several subspecialists, most commonly a nephrologist, cardiologist or neurologist. Recent advances in therapy have rendered early and precise diagnosis critical if the patient is to fully benefit. Most patients have more than one organ involved and therefore the finding of a combination of any of the features below should heighten the suspicion of amyloidosis:
The kidney is the organ most commonly involved in AL amyloidosis and AA amyloidosis, however, rarely involved in hATTR amyloidosis. Excessive amounts of protein in the urine (proteinuria) is the usual manifestation of renal involvement and is commonly heavy, resulting in the nephrotic syndrome. Less commonly, amyloid causes an excess of urea and other nitrogenous wastes in the blood (progressive azotemia) as the initial manifestation of renal disease. An abnormal accumulation of fluid (edema), such as swelling of the legs and abdomen, in the absence of heart failure is a feature of nephrotic syndrome, as is the presence of excess cholesterol in the blood (hypercholesterolemia) that may be profound. The kidneys often become small, pale and hard, but in amyloidosis, large kidneys are commonly seen as well.
Amyloidosis frequently involves the heart. The heart is commonly involved in AL and ATTRm amyloidosis and is the most common phenotype of ATTRwt amyloidosis. Amyloid infiltration of the heart results in ventricular wall thickening and the development of heart failure. Rapidly progressive congestive heart failure with thick ventricular walls is the classical presentation of AL cardiac amyloidosis. The heart is invariably involved in senile amyloidosis, often in TTR amyloidosis and almost never in the secondary amyloidosis. Common symptoms of heart involvement include: an enlarged heart (cardiomegaly); an irregular heartbeat (arrhythmias); and abnormalities of the heart seen on electrocardiograms (for example: low voltage). Congestive heart failure is the most common cardiac complication of amyloidosis. Nodular deposits of amyloid may be present on the membranous sac that surrounds the heart (pericardium) and on the lining of the heart chambers or heart valves (endocardium).
Although less common than renal or cardiac involvement, neuropathy may be a significant problem in amyloidosis. Occasionally, it is the presenting and predominant feature of AL amyloidosis. In specific mutations of hereditary amyloidosis (particularly V30M originally known as familial amyloid polyneuropathy), it is the primary feature of the disease. The neuropathy is often painless and sensorimotor in nature although neuropathic pain may be occasionally significant. These symptoms may include: sensory neuropathy with numbness and tingling sensations in the feet that progresses to the legs and eventually the upper extremities; motor neuropathy with loss of motion beginning in the feet and extending upward. Carpal tunnel syndrome is commonly seen, not due to direct nerve involvement, but rather to soft tissue infiltration causing median nerve compression. In hATTR amyloidosis, the peripheral neuropathy is frequently accompanied by an autonomic neuropathy characterized by diarrhea and a decrease in the amount of sweat production (hypohidrosis), a sudden drop in blood pressure when the patient stands up (postural hypotension) and, in the male, erectile dysfunction. Postural hypotension may be profound and result in recurrent fainting (syncopal) episodes. Systemic amyloidosis does not involve the central nervous system, and is unrelated to Alzheimer disease.
Amyloidosis may affect the liver and the spleen. Amyloid involvement in the spleen increases the risk of spontaneous rupture of that organ. Some degree of hepatic involvement is common in AL amyloidosis. It is also common in AA amyloidosis but is not seen in hATTR amyloidosis. In most patients, hepatic involvement is asymptomatic. An enlarged liver (hepatomegaly) and an enlarged spleen (splenomegaly) are the most notable signs. Generally, the amyloid-infiltrated liver feels very hard, and elevated liver enzymes (particularly alkaline phosphatase) and other liver function abnormalities may be detected early. Generally, the function of the liver is not significantly affected until late in the course of the disease. Elevation of bilirubin is an ominous sign and may portend hepatic failure. Hepatic amyloidosis rarely occurs in isolation and is usually associated with organ involvement elsewhere.
Amyloidosis may also affect the gastrointestinal (digestive) system. Amyloid accumulation in the gastrointestinal tract may cause a lack of movement (motility) in the esophagus and the small and large intestines. Malabsorption, ulceration, bleeding, weak gastric activity, pseudo-obstruction of the gastrointestinal tract, protein loss, and diarrhea may also occur. Loss of taste, and a difficulty eating solid foods because of enlargement of the tongue (macroglossia) from amyloid infiltration, may contribute to weight loss, or weight loss may be a non-specific manifestation of the systemic disease. In patients with autonomic neuropathy, gastric emptying is impaired, resulting in a sensation of early satiety.
The skin is frequently involved in primary amyloidosis. Dermatologic involvement is almost exclusively limited to AL amyloidosis and consists of soft tissue, skin and vascular abnormalities. Periorbital purpura is a result of capillary fragility and may appear after coughing, sneezing, or straining for a bowel movement. Not infrequently, purpuric lesions may arise after such simple actions as rubbing the eyelids. Soft tissue infiltration may cause macroglossia and hoarseness, although examination of the vocal cords may appear normal. Lesions of the skin may be visible or may be so small that they may be seen only with a microscope. Waxy-looking papular lesions may appear on the face and the neck. They may also occur under the arms (axillary region), near the anus and the groin. Other areas that may be affected are the mucous areas such as the ear canal or tongue. Areas of swelling, hemorrhages under the skin (purpura), hair loss (alopecia), inflammation of the tongue (glossitis) and a dry mouth (xerostomia) may also be present.
Problems with the respiratory system that are associated with amyloidosis often parallel cardiac symptoms. In the localized form of amyloidosis, air passages and ducts may be obstructed by amyloid deposits in the nasal sinuses, voice box (larynx) and throat (trachea) and bronchial tree. Fluid collecting in the pleural space (pleural effusion) is quite common in patients with congestive heart failure due to amyloidosis, but large recurrent pleural effusions disproportionate to the degree of heart failure suggest pleural amyloidosis.
Joint abnormalities (arthropathy) occur in amyloidosis due to the accumulation of amyloid deposits in the lining of joints (synovial membranes). This occurs in AL amyloidosis and occasionally in dialysis-related amyloidosis. Articular cartilage or the synovial membrane and fluid may become involved as well. Symptoms are similar to those of rheumatoid arthritis. Amyloid deposits in muscle tissue may cause muscle weakness and muscle changes (pseudomyopathy). Symptoms of amyloidosis may also be manifested by bleeding disorders. These may result from deficiency of certain clotting factors or small amyloid deposits in blood vessels within the skin.
Dialysis-related beta2-microglobulin amyloidosis usually affects the bones and joints. Initial symptoms include carpal tunnel syndrome, shoulder pain and inflammation of the tendon sheaths of the hands. Case reports of severe pulmonary hypertension and heart failure also exist.
Amyloidosis is caused by abnormal folding of normal soluble proteins leading to fibril formation in one or more body organs, systems or soft tissues. These clumps of protein are called amyloid deposits and the accumulation of amyloid deposits causes the progressive malfunction and eventual failure of the affected organ. Normally, proteins are broken down at about the same rate as they are produced, but these unusually stable amyloid deposits are deposited more rapidly than they can be broken down.
The cause of AL amyloidosis is usually a plasma cell dyscrasia, an acquired abnormality of the plasma cell in the bone marrow with production of an abnormal light chain protein (part of an antibody). Usually an excess amount of antibody protein is produced and the abnormal light chain portion or the whole antibody molecule accumulates in the body tissues in the form of amyloid deposits.
AA amyloidosis is caused by the inflammatory disease process that is part of the underlying disease. Approximately 50% of the people with secondary amyloidosis have rheumatoid arthritis as the underlying disease.
Familial amyloidosis (hATTR) is caused by an abnormality in the gene for one of several particular proteins. The most common form of hereditary amyloidosis is caused by an abnormality (mutation) in the gene for transthyretin. More than 100 different mutations in the transthyretin gene have been reported and the most common mutation has been termed V30M. Different TTR gene mutations are associated with amyloidosis that affects different organ systems. Rarely, mutations in genes for proteins that cause amyloidosis are fibrinogen A alpha chain, apolipoprotein A1 and A2, gelsolin, LECT2 and cystatin C.
All the hereditary amyloidoses follow autosomal dominant inheritance. Most genetic diseases are determined by the status of the two copies of a gene, one received from the father and one from the mother. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary to cause a particular disease. The abnormal gene can be inherited from either parent or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from an affected parent to an offspring is 50% for each pregnancy. The risk is the same for males and females. Not every person getting the gene, however, will ultimately get sick with amyloidosis.
The exact cause of dialysis-related beta2-microglobulin amyloidosis is not fully understood. A normally-functioning kidney can clear out beta 2-microglobulin. In some individuals on long-term dialysis or some individuals on continuous ambulatory peritoneal dialysis (CAPD), the kidneys’ inability to function properly leads to the abnormal retention and accumulation of the beta2-microglobulin protein. Some individuals with near end-stage renal failure have also developed this form of amyloidosis. Although this retention and accumulation is believed to be the main underlying factor, additional factors are required for the disorder to develop, which is why only a percentage of individuals on dialysis develop dialysis-related beta2-microglobuin amyloidosis.
It is estimated that there are approximately 4000 new cases of AL amyloidosis annually in the United States, though actual incidence may be somewhat higher as a result of under-diagnosis. While the incidence is thought to be equal in males and females, about 60% of patients referred to amyloid centers are male. AL amyloidosis has been reported in individuals as young as 20 years of age but is typically diagnosed at about age 50-65.
Individuals at risk for AA amyloidosis include those with chronic inflammatory diseases such as rheumatic arthritis, psoriatic arthritis, chronic juvenile arthritis, ankylosing spondylitis in children, inflammatory bowel disease, and familial Mediterranean fever. People with chronic infectious diseases such as tuberculosis, leprosy, bronchiectasis, chronic osteomyelitis, and chronic pyelonephritis are also at risk. Secondary amyloidosis (AA) occurs in less than 5% of individuals with these conditions.
Familial amyloidosis caused by a transthyretin mutation occurs in approximately 1 in 100,000 Caucasians in the U.S, and more commonly in African Americans (approximately 4% in that population). This condition is prevalent in Portugal, Sweden, Japan, Ireland, Spain, France, Finland, Germany and Greece. Symptoms usually begin between 40 and 65 years of age.
Though both familial and AA amyloidosis are probably less common than AL amyloidosis, ATTRwt amyloidosis is probably more common, but considerably underdiagnosed.
Particularly in the case of AL amyloidosis, early diagnosis is the key to survival and post treatment regaining of quality of life. The diagnosis of amyloidosis is suspected following a detailed patient history and clinical evaluation but requires aspiration of abdominal fat pad and/or biopsy of the involved organ. If the disease is suspected on clinical grounds, a biopsy of the involved organ will give the highest yield. The biopsy material is examined microscopically and is stained with a dye called Congo red that will produce a green color when looked at in a polarizing microscope if amyloid is present. When amyloidosis is diagnosed on a tissue biopsy it is essential that the affected individual be further evaluated to determine what organs are affected.
Once a tissue biopsy of amyloidosis has been established, it is crucial to determine the type of amyloidosis. In AL amyloidosis, manifestations of a plasma cell dyscrasia will be found in 98% of the time. In 2% of cases, a B-cell lymphoma is identified as the cause of AL amyloidosis. The specific tests that are used to make a diagnosis of the plasma cell dyscrasia or B-cell clone are immunofixation and protein electrophoresis of the blood and urine, bone marrow biopsy with immunochemical staining of plasma cells for kappa and lambda light chains and a serum free light chain assay. The diagnosis of TTR hereditary amyloidosis can be confirmed by performing molecular genetic testing for mutations in the TTR gene on a blood sample. In the absence of mutations of transthyretin, very rare forms of familial amyloidosis may be present.
If the patient is an elderly man with clinically isolated cardiac involvement, the most likely diagnosis is ATTRwt amyloidosis a condition in which wild-type (normal) transthyretin is deposited in the heart.
Specific immunostaining (for example, immunogold electron microscopy) of appropriately preserved tissue is available at specialized centers and offers a high specificity for determining the accurate type of amyloid. In difficult diagnostic cases, mass spectrometry is able to determine precisely the molecular structure of the amyloid deposits– this technique is being used more and more frequently. A technique called radiolabeled serum amyloid P (SAP) scanning is available in a few centers in Europe that specialize in amyloidosis. This test is used to monitor and evaluate the extent of accumulation of amyloid deposits.
In individuals on long-term dialysis or with end stage renal failure, lab tests may be performed that can analyze blood or urine samples to detect increased levels B2M protein.
The type of treatment available is driven by the type of amyloidosis and the clinical state of the patient. In AL amyloidosis, the cause is the abnormal plasma cells and as such, chemotherapy aimed at eradicating those cells forms the cornerstone of treatment. Various regimens have been studied but the ones with the most historical evidence are Evomela (melphalan) and Dextenza (dexamethasone) given orally or high-dose melphalan given intravenously with autologous stem cell transplantation. Both are equally effective but the treatments and side effects are different. High dose melphalan with stem cell transplantation is an involved treatment that often involves a 2-3 week hospital stay and a few months of additional recovery time. The use of oral melphalan on a monthly basis is less toxic, but is associated with a higher risk of treatment-related leukemia. Newer agents active in multiple myeloma (another disease of abnormal plasma cells), such as Velcade (bortezomib) or Revlimid (lenalidomide), are also very effective in AL amyloidosis and have been shown to provide a benefit in patients with relapsed disease. Often times, these drugs are incorporated into upfront treatment. Currently, most patients not getting high dose melphalan with stem cell support transplantation are having getting novel therapies upfront. The combination of bortezomib, Cytoxan (cyclophosphamide) and dexamethasone is associated with good tolerability and rapid responses. The specific treatment for any individual has to be personalized to their unique situation.
The two most important determinants of long-term survival with AL are the presence and extent of cardiac involvement and hematologic response to therapy.
Supportive therapy (treatment of congestive heart failure, attention to nutrition, treatment of autonomic neuropathy etc.) is a very important concomitant measure. Given the complexity of the disease, it is recommended that treatment be performed in a center with experience in amyloidosis, or at least that the patient should have an initial evaluation at such a center, with continued communication during treatment in the local community.
Hereditary TTR amyloidosis is treated, if possible, by removal of the source of the abnormal TTR production. Since the dominant source is the liver, liver transplantation is performed in carefully selected patients whose disease is not too far advanced. Onpattro (patisiran) and Tegsedi (inoteresen) are TTR gene silencers and have been approved by the Food and Drug Administration (FDA) for treatment of ATTRm amyloidosis with peripheral neuropathy. In 2019, the FDA approved Vyndaqel (tafamidis meglumine) to treat the cardiomyopathy (heart disease) caused by ATTR (ATTR-CM).
Genetic counseling is recommended for individuals with hereditary amyloidosis and their family members.
In ATTRwt amyloidosis, therapy is supportive, but both for this disease and for ATTR, pharmacologic therapies aimed at stabilizing the transthyretin molecule and thus preventing amyloid formation are being actively investigated.
The mainstay of AA amyloidosis treatment is therapy of the underlying disease. Renal transplantation has been performed successfully for renal disease due to AA amyloidosis.
Eprodisate is a small molecule that inhibits the formation of amyloid fibrils, and which seems to have a modest clinical effect in patients with AA amyloidosis.
In 2015, the FDA authorized the use of a medical device called Lixelle Beta 2-microglobulin apheresis column to treat dialysis-related beta2-microglobulin amyloidosis. The device works by removing the beta 2m protein from the blood.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
For information about clinical trials sponsored by private sources, contact:
For information about clinical trials conducted in Europe, contact:
Amyloidosis Treatment Centers
Medical centers that provide diagnosis and treatment for amyloidosis and conduct research and clinical trials can be located here:
International Amyloid Centers
Italian center for the Study and Cure of Systemic Amyloidosis (Pavia, Italy)
National Amyloidosis Center, London, UK.
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