Molecular stratification of Crohn's disease by chemokine receptors: fractalkine receptor polymorphisms define a fibrostenosing ileal subgroup.

The association of NOD2/CARD15 gene mutations with Crohn's disease (CD) has also provided proof of principle that anatomic location (ileal disease) and stricturing behavior is associated with specific genetic variants. However, the majority of CD patients of Caucasian descent, and essentially all minority CD patients do not possess NOD2/CARD15 mutations. Although these early lessons from NOD2/CARD15 genotype/phenotype correlations are encouraging, much more needs to be done to adequately understand the CD spectrum of subgroups. The study by Brand et al. demonstrates that a chemokine receptor polymorphism (CX3CR1 T280) can also influence disease location and behavior, suggesting yet another genetic variant that can help to subgroup CD patients. Findings similar to the study by Brand and colleagues in this issue of American Journal of Gastroenterology suggest that panels of susceptibility alleles and polymorphisms will ultimately allow an early genetic determination that will correspond with unique clinical patterns of CD: increased expression of the chemokine fractalkine in Crohn's disease and association of the factalkine receptor T280M polymorphism with a fibrostenosing disease phenotype.