Variants of CARD15 are associated with an aggressive clinical course of Crohn's disease--an IG-IBD study

BACKGROUND: Three major variants of the CARD15 gene confer susceptibility to Crohn's disease (CD). Whether or not these variants correlate with specific clinical features of the disease is under evaluation. AIM: We investigated the possible association of CARD15 variants with specific clinical characteristics, including the occurrence of anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies (ANCA), in a large cohort of inflammatory bowel disease (IBD) patients and their unaffected relatives. METHODS: Three hundred and sixteen CD patients (156 with positive family history), 408 ulcerative colitis (UC) patients (206 with positive family history), 588 unaffected relatives, and 205 unrelated healthy controls (HC) were studied. Single nucleotide polymorphisms (SNPs) R702W, G908R, and L1007finsC of the CARD15 gene were investigated and correlated to age at diagnosis, gender, family history, localization, extraintestinal manifestations, previous resective surgery, stenosing/fistulizing pattern, ANCA, and ASCA. RESULTS: Compared to HC, the frequencies of all three variants in CD were significantly increased: 8.7% versus 4.1% for R702W (p < 0.006), 7.3% versus 2.7% for G908R (p < 0.002), 9.3% versus 0.7% for L1007finsC (p < 0.00001). At least one risk allele was found in 38.2% (p < 0.0001, compared to HC), 13.7% (NS), and 15.1% of CD, UC, and HC, respectively. The L1007finsC risk allele was also significantly increased in unaffected relatives of familial (9.5%; p < 0.00001), and sporadic CD (9%; p < 0.00001), compared to HC (0.7%). Sixteen healthy relatives, carriers of two risk alleles, were asymptomatic after 5-8 yr of follow-up. CD carriers of at least one variant were younger (p= 0.03), more likely to have ileal localization (p= 0.0001), stenosing pattern (p= 0.01), previous resective surgery (p= 0.0001), and presence of ASCA (p= 0.0001). No difference in SNPs frequency between familial and sporadic cases of CD was found. CONCLUSION: In our population, both familial and sporadic CD patients carrying at least one major variant of CARD15 had an aggressive clinical course.