A BACH2 Gene Variant Is Associated with Postoperative Recurrence of Crohn's Disease.

Background: Crohn's disease often requires intestinal resection, which is not considered curative. Repeat surgical intervention is necessary in more than half of patients after their initial operation. Although many genetic loci are implicated in Crohn's disease, few have been associated with post-resection recurrence.

Study Design: A cohort of patients with Crohn's disease who underwent intestinal resection was analyzed to determine genetic and clinical factors associated with post-resection recurrence. Genotype was assessed at 8 loci associated with adaptive immunity (SMAD3, IL10RB, IL15RA, BACH2, IL12B, IL18RAP, IFNGR2, and JAK2). Univariate and multivariable survival analyses were performed using a log-rank test and Cox-proportional hazard model, respectively.

Results: One hundred and ninety-one patients with Crohn's disease and 11.2 years mean postoperative follow-up were included. Forty-six percent experienced a surgical recurrence. Factors associated with increased incidence of recurrence included male sex (p = 0.05) and shortened time to first intestinal operation (5.0 vs 7.3 years; p = 0.03); inflammatory disease behavior was associated with a lower chance of repeat operation (p < 0.01). Of the loci assessed on multivariable analysis, homozygosity for a risk allele at BACH2 (rs1847472) was significantly associated with disease recurrence (hazard ratio 1.54; 95% CI 1.00 to 2.36; p < 0.05).

Conclusions: We identify BACH2 as a susceptibility locus for postoperative recurrence of Crohn's disease in our cohort. BACH2 is critical in the differentiation and function of T cells, as a regulator of B-cell activity, and is associated with several dysregulated immunologic phenomena. Its identification as a risk locus in postoperative Crohn's disease recurrence suggests a potential role for regulatory T cells, effector T cells, humoral immunity, and immunologic memory in the development of this disease process.