CARD15 mutation analysis in an Italian population: Leu1007fsinsC but neither Arg702Trp nor Gly908Arg mutations are associated with Crohn's disease

Background: CARD15 gene mutations have been demonstrated to confer a high risk of Crohn's disease (CD). Despite this, recent studies reported variable associations between CD and CARD15 mutations in distinct ethnic groups, thus raising the hypothesis that genetic and/or allelic heterogeneity may influence the relationship between CARD15 and CD. The purpose of this study was to evaluate the frequency of the main mutations of the CARD15 gene (Leu1007fsinsC, Arg702Trp, and Gly908Arg) in Italian CD patients and to establish possible genotype-phenotype correlations. Methods: One hundred sixty-five CD patients and 125 healthy subjects were consecutively enrolled from January to November 2001. The Leu1007fsinsC mutation was assessed by denaturing high-performance liquid chromatography and Arg702Trp and Gly908Arg mutations by Pyrosequencing technology. Results: Among the CARD15 gene mutations tested, only the Leu1007fsinsC was associated with CD (30/165 CD patients, 18%, versus 3/125 healthy subjects, 2.4%; p <0.001). In particular, 23 CD patients were heterozygotes and 7 were homozygotes. No healthy subject exhibited the mutant homozygous genotype. Odds ratios for CD were 6.9 for heterozygotes and 41.0 for homozygotes. The genotype-phenotype analysis revealed that a fibrostenosing CD of the distal ileum was more frequent in patients carrying the Leu1007fsinsC mutation. Conclusions: This study confirms the association between CARD15 gene mutations and CD and shows that only the Leu1007fsinsC mutation is a risk factor of CD in an Italian population.