Spondylitis Association of America
It is known that ankylosing spondylitis has a large genetic component, making it more common among those of the same family when a disease history is present.
A study published in the "Annals of Rheumatology" reinforces the evidence of this, by concluding, "Patients with AS in Iceland are significantly more related to each other than to randomly sampled control subjects. This is in agreement with previous reports on the familiality of AS, but the present study has more power and extends over larger familiar cohorts than previously reported."
Other current research into spondylitis is seeking the genes that cause AS.