Ankylosing spondylitis (AS) is a painful joint inflammation condition that mostly affects the spine. Early symptoms can include back pain and stiffness and begin between the ages of 15 and 30. The pain from this condition usually gets worse after periods of rest and inactivity. Symptoms decline with exercise or some other form of physical activity.
AS is one of the most common rheumatic diseases. It is a highly inheritable inflammatory disease and affects mostly the axial joints. It can affect the peripheral joints and organs as well. The manner of the disease process is unknown. There is a high prevalence among the Caucasian population. The HLA-B27 gene is found in over 85% of diagnosed patients.
Scientists acknowledge the importance of the HLA-B27 gene, which is thought to be overall responsible for 30% of genetic risks. However, there are several other genes with smaller effects that, when combined, make for an effective outcome in increasing the AS risk. Each of these smaller genes, because of their smaller roles in AS, is hard to locate. Still, the establishment of a global syndicate to share information and combine genetic samples has created an effective genome mapping sample.
The HLA-B27 gene codes biologically for protein creation which is important in the immune system. It helps the immune system distinguish between foreign invaders like bacteria and viruses. It has numerous normal variations. It is well known to increase the risk of AS, but scientists do not know how. Many other smaller genes have somewhat been associated with AS. They include IL1A, IL23R, and ERAP1. Research scientists are trying to further dissect these genes and clarify the role that they play in developing AS. Changes in unidentified genes are also very likely to put people more at risk for AS and influence the progression of the disorder.
Though ankylosing spondylitis can be found in more than one family member, it is not purely genetic. Several genetic and environmental influences can play a part in the risk of developing the disorder, so inheriting a variation linked genetically to AS does not mean they will get the condition. This is true even if multiple family members have AS. A study showed that about 75 % of kids who had inherited the HLA-B27 gene from their parents with the condition did not develop the disease.
