Observations of children with IBD often suggest a more severe course than that found in adults. Explanations for this are unclear, especially since children are less likely to engage in some behaviors (e.g., smoking) that may have a deleterious effect on disease course as noted in adults. In many ways children are a better "experimental model" of IBD because they don't have as many confounding medical factors as adults. Both Crohn's disease and ulcerative colitis are believed to result from a complex interaction of genetic and environmental factors (1). Recently, the gene CARD15/NOD2 on chromosome 16 has been identified in approximately 25% of Caucasian patients with Crohn's disease and is felt to be a significant predisposing factor to the development of fibrostenosing disease (2). Additionally, seropositivity for perinuclear antinuclear cytoplasmic factor (pANCA) has been demonstrated much more frequently in patients with ulcerative colitis than in those with Crohn's disease, while anti-Saccharomyces antibody (ASCA) is more common in the latter population (3). The importance of these serological abnormalities is not clear, though some data suggest an influence on the development of complications.