Comparative phenotypic and CARD15 mutational analysis among African American, Hispanic, and White children with Crohn's disease.

Background: Despite a large body of literature on the subject of Crohn's disease (CD), very little information is available on racial/ethnic differences related to disease presentation, clinical course, and genetics. The first identified CD susceptibility gene, CARD15, seems to be present in up to 40% of white children with CD. However, the frequency of this gene among patients with CD of other racial/ethnic groups in the United States is not known.

Methods: We conducted a multicenter study on African American and Hispanic children with CD to describe the phenotypic and genotypic (CARD15) features in comparison with white children with CD. We also analyzed the frequency of CARD15 mutations in large control samples from white, African American, and Hispanic children.

Results: The disease location and behavior were similar among all 3 groups, with inflammatory behavior and the ileocolonic location being the most frequent phenotype. However, significantly lower frequencies of CARD15 mutations were seen in African American (P < 0.0001) and Hispanic (P < 0.0001) children with CD compared with white children with CD. This lower CARD15 frequency among African American patients with CD was also mirrored in the general population.

Conclusions: Phenotypic features of CD are similar among African American and Hispanic children compared with white children. CARD15 mutations are not increased among African American and Hispanic children with CD. CARD15 mutational frequencies among African American and Hispanic children within the general population are lower compared with white children within the general population. Future genetics studies will be required to determine the relationships between genotype and CD phenotype in various ethnic and racial groups.