Objective: To examine the association between single-nucleotide polymorphisms (SNPs) in CTGF (connective tissue growth factor) and patient outcomes after terminal ileal resection for Crohn's disease.
Background: The primary indication for intestinal resection in Crohn's disease is fibrostenotic terminal ileal disease. CTGF is a cytokine overexpressed in the intestine of patients with Crohn's disease that influences outcomes in other disease processes.
Methods: DNA was extracted from formalin-fixed, paraffin-embedded tissue from 147 patients with Crohn's disease who had undergone terminal ileal resection between 1981 and 2009. Genotyping was performed for 4 CTGF SNPs (rs9402373, rs12526196, rs6918698, and rs9399005), which modulate nuclear factor binding and CTGF production, and a smad3 SNP (rs17293632) involved in the CTGF pathway. Patients were phenotyped using the Montreal Disease Classification.
Results: Sixty-seven of 147 patients (45.6%) were male; the mean age at diagnosis was 30.3 ± 12.6 years and the mean follow-up duration was 8.3 ± 7.1 years. Genotype-phenotype analysis demonstrated that the rs6918698GG genotype was associated with an older age of disease onset [>40 years; 30.6% vs 13.2%; odds ratio (OR): 2.891; 95% confidence interval (CI): 1.170-7.147). The rs9402373CC genotype was positively associated with type B1 disease (50.7% vs 26.3%; OR: 2.876; 95% CI: 1.226-6.743) and negatively associated with B2 disease (37.0% vs 65.0%; OR: 0.317; 95% CI: 0.144-0.699). None of the 5 SNPs assessed influenced clinical or surgical recurrence of Crohn's disease after intestinal resection. On multivariate analysis, male sex odds ratio (OR): 0.235; 95% CI: 0.073-0.755; P = 0.015] and never having smoked tobacco (OR: 0.249; 95% CI: 0.070-0.894; P = 0.033) reduced the risk, whereas having a prior appendectomy increased the risk (OR: 5.048; 95% CI: 1.632-15.617; P = 0.005) of surgical recurrence.
Conclusions: These data implicate the rs6918698GG genotype with an age of disease onset of greater than 40 years in Crohn's disease whereas the rs9402373CC genotype is associated with a nonstricturing, nonpenetrating disease phenotype. CTGF SNPs do not influence the rate of recurrence after terminal ileal resection for Crohn's disease.