Genetic risk profiling and prediction of disease course in Crohn's disease patients

Clinical presentation at diagnosis and disease course of Crohn's disease (CD) are heterogeneous and variable over time. Early introduction of immunomodulators and/or biologicals might be justified in patients at risk for disease progression, so it is important to identify these patients as soon as possible. We examined the influence of recently discovered CD-associated susceptibility loci on changes in disease behavior and evaluated whether a genetic risk model for disease progression could be generated.

Complete medical data were available for 875 CD patients (median follow-up time, 14 years; interquartile range, 7-22). Fifty CD-associated polymorphisms were genotyped. Kaplan-Meier survival analyses, multiple logistic regression, and generalized multifactor dimensionality reduction analyses (GMDR) were performed, correcting for follow-up time.

Homozygosity for the rs1363670 G-allele in a gene encoding a hypothetical protein near the IL12B gene was independently associated with stricturing disease behavior (odds ratio [OR], 5.48; 95% confidence interval [CI], 1.60-18.83; P = .007) and with shorter time to strictures (P = .01), especially in patients with ileal involvement (P = .0002). Male patients carrying at least one rs12704036 T-allele in a gene desert had the shortest time to non-perianal fistula (P < .0001). The presence of a C-allele at the CDKAL1 single nucleotide polymorphism rs6908425 and the absence of NOD2 variants were independently associated with development of perianal fistula (OR, 8.86; 95% CI, 1.13-69.78; P = .04 and OR, 0.56; 95% CI, 0.38-0.83; P = .004, respectively), particularly when colonic involvement and active smoking were present.

CD-associated polymorphisms play a role in disease progression and might be useful in identifying patients who could benefit from an early top-down treatment approach.