Amyloidosis Disease Types

Amyloid deposits cause a number of common and rare diseases. Some, such as Alzheimer’s disease and type 2 diabetes, are well-known disorders. Others, such as multiple myeloma and familial Mediterranean fever, are rare and relatively unknown to the general public.

Primary Amyloidosis and Multiple Myeloma

Primary amyloidosis is also called amyloid light chain, or AL. AL is associated with plasma cell disorders, rare diseases that cause excessive antibody production. AL is sometimes diagnosed as multiple myeloma, a rare form of bone marrow cancer.

Rare diseases associated with AL include the following:

  • multiple myeloma
  • light-chain disposition disease (LCDD)
  • monoclonal gammopathy of undetermined significance (MGUS).

Light chain disease causes antibody light chains to build up in multiple organs. MGUS indicates abnormal proteins in the blood stream. Although MGUS may not cause symptoms, in about twenty percent of cases a more serious condition develops as a result of these proteins.

Often, no underlying disorder can be found to explain the presence of primary amyloidosis. When no cause can be found, the condition is called idiopathic amyloidosis.

What’s an Antibody?

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Antibodies, or immunoglobulins, are important agents in the body’s immune system. An antibody is capable of identifying antigens (foreign substances), such as bacteria and viruses. Once identified, antigens are treated as a threat, and the antibody tags the foreign body for removal by white blood cells.

An antibody is composed of four strings of amino acids called polypeptides. Two of these are “heavy” chains, and two are “light.” The four amino acid chains combine to form a Y-shaped antibody molecule.

Secondary Amyloidosis and Chronic Inflammation

Secondary amyloidosis is caused by a number of disorders that cause chronic inflammation. Chronic inflammation causes tissue damage, which in turn results in an increase in serum amyloid-associated (SAA) protein. SAA is then used to form “amyloid associated” proteins, which build up in the organs.

A number of common chronic inflammation disorders have been linked to secondary amyloidosis:

  • Crohn’s disease
  • Hodgkin’s disease
  • rheumatoid arthritis
  • syphilis
  • tuberculosis.

Alzheimer’s Disease

Alzheimer’s disease causes a slow decline in cognitive functions and memory. One form of dementia, Alzheimer’s disease, affects approximately four million people in the United States today.

Although the exact cause of Alzheimer’s is unknown, autopsies reveal three different types of lesions on patients’ brains: senile plaques, neurofibrillary tangles and vascular lesions. Senile plaques and vascular lesions contain high levels of beta-amyloid protein, suggesting that Alzheimer’s may be a form of amyloidosis.

Type 2 Diabetes

Amyloid deposits in the pancreas have been linked to type 2 diabetes. One study that performed autopsies on people who had type 2 diabetes discovered protein deposits in the pancreas in ninety percent of cases. The deposits are thought to interfere with the ability of the pancreas to release appropriate amounts of insulin.

Prion Disorders

Prions are proteins that have mutated and become infectious. The prions build up in the brain and can cause several different forms of degenerative neurological disorders. Perhaps the most infamous prion disorder is bovine spongiform encephalopathy, or mad cow disease. The human equivalent is an aggressive degenerative disease called Creutzfeldt-Jakob.

The mutated prion protein PrPSc has structural similarities to amyloid deposits. The mutated proteins have long life spans, and can convert normal PrP proteins into the PrPSc variation. The resulting accumulation of prion deposits causes neurological damage.

Familial Amyloidosis

Familial forms of amyloidosis are rare. In the majority of cases, no evidence exists of a family history of the disorder.

Familial Mediterranean Fever (FMF) is a hereditary form of amyloidosis characterized by recurring high fevers and peritonitis (inflammation of the peritoneum, or lining of the abdominal cavity). Abdominal, chest and joint pain is also common.

As its name suggests, FMF usually affects individuals whose ethnic origins are in the Mediterranean area, including Arabs, Armenians, Sephardic Jews and people of Turkish descent. However, the disorder is not restricted to these ethnic groups. Anyone can develop FMF, and a family history is present only in fifty percent of cases.

Familial Amyloid Polyneuropathies (FAP) are familial disorders that affect the nervous system. Amyloid deposits slowly cause nerve degeneration. Such hereditary conditions are rare.