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Gene May Link Inflammatory Disease Of Spine/Joints, Skin, Eye And Bowel

A shared gene may account for a striking overlap of rheumatological, dermatological, and gastroenterological diseases within patients and family members.

This is the suggestion of a study of genetic, phenotypic and environmental factors in inflammatory eye, skin and bowel disease in spondyloarthritis.

Study objective was to explore the nature of the interrelationship between inflammatory disease of the spine/joints, skin, eye, and bowel (ie, ankylosing spondylitis [AS], psoriasis, iritis, inflammatory bowel disease [IBD]).

The researchers used four different approaches: 1) analysis of the prevalence of secondary disorders within the AS individual (chi-square and matched pair analysis); 2) study of the temporal relationship between the onset of the different conditions; 3) evaluation of the prevalence of disease among first-degree relatives; and 4) influence of secondary disorders on outcome of AS.

Study participants were 3,287 patients with AS. Among these patients, more than expected had either spondylitis linked with multiple co-disorders or pure AS (with no co-diseases); fewer than expected had AS plus a single co-disease.

In a matched pair analysis, patients with AS and a secondary disorder were more likely to have an additional concomitant disease.

For example, compared with controls, the 335 patients with IBD-AS had a higher prevalence of iritis (45.4 percent versus 36.7 percent) or psoriasis (23.9 percent vs. 14.3 percent).

Among subjects in the study database, the symptomatic onset of the spinal disease precedes or is contemporaneous with gut, skin, and eye involvement.

Patients with multiple disorders predict the highest prevalence of co-diseases (ie, psoriasis, IBD, iritis, or AS) within family members, followed by those AS patients with only IBD, psoriasis, or iritis in descending order.

Both psoriasis and IBD increase severity in terms of function and disease activity of AS in the patient. Radiological change is greatest for those AS subjects with iritis.

Thus, in summary, these authors note the susceptibility genes of inflammatory disease of the spine/joints, skin, eye, and bowel appear to overlap with each over and AS.

A patient with two inflammatory conditions is at an increased risk of developing an additional related inflammatory disorder.

People with enteropathic spondylarthritis would appear to carry the greatest genetic load in terms of first-degree relatives developing inflammatory conditions (including psoriasis and iritis that are not seen in the index IBD-AS patient).

The secondary disorders do not precede AS, which argues against psoriasis and IBD allowing for an environmental conduit to pathogenic triggers in AS.

Thus, the susceptibility factors for these inflammatory conditions may be additive or have a synergistic effect on each other, and there is evidence for a shared gene hypothesis, study authors conclude.
J Rheumatol 2001;28:2667-73. "Inflammatory Eye, Skin, and Bowel Disease in Spondyloarthritis: Genetic, Phenotypic, and Environmental Factors"

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