Rheumatology
Arthritis Complicating Inflammatory Bowel Disease – Prevalence and Genetic Predictors
Dr Phillip Vecchio
Ankylosing spondylitis (AS) is known to be clinically associated with inflammatory bowel disease (IBD). The prevalence of AS in IBD is not well established, with studies suggesting that between 3-28% of cases have sacroiliitis (1,2), and ~10% having clinical AS, compared with a prevalence of AS of 4/1000 in the general community. We and others have previously demonstrated that the major gene for Crohn’s disease, CARD15, is not associated with AS, nor is it associated with IBD complicating AS (3,4). Whether HLA-B27, the major gene for AS, is associated with IBD, has not been well studied. We have recently demonstrated that polymorphisms of IL23R contribute 19% of the population attributable risk of AS (5), and contemporaneously others have established that a similar association exists with IBD (6).
We hypothesize that IBD patients that carry disease-associated IL23R polymorphisms, either alone or in combination with HLA-B27, are at high risk of AS complicating IBD, and that genetic tests may be of significant diagnostic and prognostic value in determining those IBD cases either with, or at risk of, AS.
In the current study we wish to determine the prevalence and pattern of axial spondyloarthritis in IBD, and the predictive and diagnostic value of HLA-B27 and IL23R genetic tests in this setting.
We also wish to establish a cohort of IBD cases characterised for arthritis for future genetic studies.
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