Amyloidosis (amyloidosis) - Gen SAA1.


Amyloidosis is a disorder in which amyloid protein deposits accumulate in the body. These abnormal clusters of proteins called amyloid deposits and can lead to kidney failure if untreated. Amyloidosis can affect the tongue, intestines, skeletal and smooth muscles, nerves, skin, ligaments, heart, liver, spleen and kidneys.

Signs and symptoms of the disease depend on the organs affected and can include abnormal heart rhythm, tongue swelling, fatigue, numbness in hands and feet, shortness of breath, skin changes, trouble swallowing, swelling of arms and legs, weakness to hold by hand, weight loss, decreased urine output, diarrhea, hoarseness, voice changes, joint pain and weakness.

This process is due to mutations in the SAA1 gene, located on the short arm of chromosome 11 (11p15.1). This gene encodes a protein called amyloid A1 serum. This protein is mainly synthesized in the liver and circulates at low concentrations in the blood. Although its function is not fully understood, the serum amyloid A1 appears to play a role in the immune system. The protein can help repair damaged tissues, acting as an antibacterial agent, directing the migration of cells that fight infection. The concentrations of this protein increases in the blood and other tissues during inflammation. Inflammation occurs when the immune system sends signaling molecules and leukocytes from the blood to a site of injury or disease to combat microbial invaders and facilitate tissue repair. When this has been accomplished, the body stops the inflammatory response to prevent damage to its own cells and tissues. Three versions of serum amyloid A1 protein, known as alpha, beta, and gamma, which differ in one or two amino acids. The frequency of these variants differs between populations. In Caucasian populations, predominantly alpha and gamma version version is rare. However, in the Japanese population, the three versions appear almost equally.

Although it is unclear, how mutations in the SAA1 gene increase susceptibility to amyloidosis, more units of this protein are encoded in the body in response to chronic inflammation. Consequently, this protein and related compounds can form abnormal lumps in organs and tissues.

Tests in IVAMI: in IVAMI perform detection of mutations associated with amyloidosis, by complete PCR amplification of the exons of the SAA1 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).