Interaction Between Sex, HLA-B27, and IBD Subtypes in Sacroiliitis

Sacroiliitis (SI) is reported to develop in up to 20% of patients with inflammatory bowel disease (IBD). While sex and the HLA-B27 allele have been reported to be associated with sacroiliitis in the general population, large-scale studies have not been performed in IBD.

A poster presentation at the annual Digestive Disease Week conference reported results from two cohorts in one study that aimed to determine the association between the HLA-B27 allele and SI in men with Crohn’s disease (CD).

In this exclusive MedPage Today video, Dalin Li, PhD, a research scientist at Cedars-Sinai Medical Center in Los Angeles, explained the study design and clinical significance of the results.

Following is a transcript of his remarks:

This study is two cohorts in one study. One is the local Cedars cohort and the other one is another cohort we call SHARE.

The sample size is the largest in this type of study. And what we have found here is that it’s the HLA-B27 association with SI in IBD patients. It is different in different sexes and different disease subtypes than the CD and UC [ulcerative colitis] group.

So the HLA-B27 association is only in males and only in CD individuals. This pattern, to be frank, [is] rarely seen in genetic studies and it is very consistent between the two cohorts. So overall, within the subgroup for male CD patients, more than 20% of individuals who have HLA-B27 is positive for SI. That is the main information we want to send out to the community.

We need some guidelines to screen these specific populations because imaging diagnosis is important for SI, and because some treatments like anti-IL [interleukin]-17F or anti-IL-17a [are] effective in delaying progression of SI. So we might consider some kind of guidelines to people in this subgroup.