9. Genes can play a role in AS
Even though scientists haven’t figured out why certain people develop ankylosing spondylitis, genes play a role. In particular, the genetic variant HLA-B27 is associated with an increased risk of developing AS, and other genes have recently been linked with the disease (such as ERAP1, IL23R, and EL1A). That said, testing for the HLA-B27 gene can’t rule out or clinch a diagnosis. Only about 2 percent of people who carry the HLA-B27 gene will go on to develop spondyloarthritis, according to the Spondylitis Association of America, and not everyone with AS has the HLA-B27 gene.
10. Race has its own risk factors
Potentially related to the prevalence of the HLA-B27 gene, which is more common among white people, Caucasians are at a greater risk of developing AS than people of other races. But according to a study of 925 ankylosing spondylitis patients, black patients have more severe disease activity than their white or Latino counterparts.
11. An earlier stage of AS form has a different name
Because of certain diagnostic criteria, it can take a notoriously long time to get diagnosed with ankylosing spondylitis. Until joint damage in the spine shows up on an X-ray (which could take up to a decade from the time you first experience symptoms), you won’t technically be diagnosed with AS.
But if you have AS-like symptoms and risk factors, you could be diagnosed with a related condition called non-radiographic axial spondyloarthritis (nr-axSpA) — “non-radiographic” refers to the lack of evidence on imaging tests. As damage progresses, your diagnosis can move along the spectrum from nr-axSpA to full-blown AS.
The reason this distinction is important is because until recently, biologic drugs have only been FDA-approved for AS and not for nr-AxSpA. This made it challenging for patients who were coping with a lot of inflammatory pain to get proper treatment. However, the first biologic drug was just approved to treat non-radiographic axial spondyloarthritis, and others will likely follow in coming months and years.