TRAF3IP2 gene is associated with cutaneous extraintestinal manifestations in Inflammatory Bowel Disease

BACKGROUND AND AIMS: Genome-wide association (GWA) studies recently identified a novel gene, TRAF3IP2, involved in the susceptibility to psoriasis. Common immune-mediated mechanisms involving the skin or the gut have been suggested. We therefore aimed to assess the role of TRAF3IP2 gene in IBD, with particular regard to the development of cutaneous extraintestinal manifestations (pyoderma gangrenosum, erythema nodosum). The association with psoriasis was also assessed in a secondary analysis. METHODS: The analysis included 267 Crohn's disease (CD), 200 ulcerative colitis (UC) patients and 278 healthy controls. Three TRAF3IP2 SNPs were genotyped by allelic discrimination assays. A case/control association study and a genotype/phenotype correlation analysis have been performed. RESULTS: All three SNPs conferred a high risk to develop cutaneous manifestations in IBD. A higher risk of pyoderma gangrenosum and erythema nodosum was observed in CD patients carrying the Rs33980500 variant (OR 3.03; P=0.026). In UC, a significantly increased risk was observed for both the Rs13190932 and the Rs13196377 SNPs (OR 5.05; P=0.02 and OR 4.1; P=0.049). Moreover, association of TRAF3IP2 variants with ileal (OR=1.92), fibrostricturing (OR=1.91) and perianal CD (OR=2.03) was observed. CONCLUSIONS: This is the first preliminary report indicating that TRAF3IP2 variants increase the risk of cutaneous extraintestinal manifestations in IBD suggesting that the analysis of the TRAF3IP2 variants may be useful for identifying IBD patients at risk to develop these manifestations.