Reviewed September 2008
What is the official name of the SAA1 gene?
The official name of this gene is “serum amyloid A1.”
SAA1 is the gene's official symbol. The SAA1 gene is also known by other names, listed below.
What is the normal function of the SAA1 gene?
The SAA1 gene provides instructions for making a protein called serum amyloid A1. This protein is made primarily in the liver and circulates in low levels in the blood. Although its function is not fully understood, serum amyloid A1 appears to play a role in the immune system. Serum amyloid A1 may help repair damaged tissues, act as an antibacterial agent, and signal the migration of germ-fighting cells to sites of infection.
Levels of this protein increase in the blood and other tissues under conditions of inflammation. Inflammation occurs when the immune system sends signaling molecules and white blood cells to a site of injury or disease to fight 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.
There are three versions of the serum amyloid A1 protein, known as alpha, beta, and gamma, which differ by one or two protein building blocks (amino acids). The frequency of these variants differs across populations. In Caucasian populations, the alpha version predominates and gamma is rare. In the Japanese population, however, the three versions appear almost equally.
How are changes in the SAA1 gene related to health conditions?
familial Mediterranean fever - course of condition modified by normal variations in the SAA1 gene
Several studies of people with familial Mediterranean fever indicate that having the alpha version of the serum amyloid A1 protein increases the risk of a serious complication called amyloidosis. Amyloidosis involves the buildup of protein deposits that can lead to kidney failure if left untreated. Studies indicate that individuals with familial Mediterranean fever who also have the alpha version of the protein are two to seven times more likely to develop amyloidosis than are people with the beta or gamma version.
More serum amyloid A1 is produced in the body during episodes of inflammation such as those that occur in familial Mediterranean fever. This protein and related compounds may form abnormal clumps in the body's organs and tissues. It remains unclear, however, how the alpha version of serum amyloid A1 increases the susceptibility to amyloidosis (or alternatively, how the beta and gamma versions may protect against this complication) in people with this disorder.
- other disorders - course of condition modified by normal variations in the SAA1 gene
Among people with certain other inflammatory disorders, studies indicate that variants of the serum amyloid A1 protein also modify the risk of amyloidosis. In the Japanese population, the gamma version of the protein appears to increase the risk of amyloidosis among adults with rheumatoid arthritis. Among Caucasians with juvenile chronic arthritis, the alpha version indicates a high risk of developing amyloidosis. The alpha version of serum amyloid A1 also appears to be a risk factor for developing amyloidosis in people with Behcet's disease, a disorder that causes inflammation of the blood vessels.
More serum amyloid A1 is produced in the body during chronic inflammation such as occurs in these disorders. This protein and related compounds may form abnormal clumps in the body's organs and tissues. It remains unclear, however, how certain versions of serum amyloid A1 increase the susceptibility to amyloidosis.
Where is the SAA1 gene located?
Cytogenetic Location: 11p15.1
Molecular Location on chromosome 11: base pairs 18,244,345 to 18,248,089
The SAA1 gene is located on the short (p) arm of chromosome 11 at position 15.1.
More precisely, the SAA1 gene is located from base pair 18,244,345 to base pair 18,248,089 on chromosome 11.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about SAA1?
You and your healthcare professional may find the following resources about SAA1 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
What other names do people use for the SAA1 gene or gene products?
- tumor protein p53 inducible protein 4
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding SAA1?
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
See How can I find a genetics professional in my area? in the Handbook.