1. ¹Department of Pathology, University of Otago, Christchurch, New Zealand
2. ²Department of Biochemistry, University of Otago, Dunedin, New Zealand
3. ³Department of Gastroenterology, Christchurch Hospital, Christchurch, New Zealand
4. ⁴Department of Medicine, University of Otago, Christchurch, New Zealand

Correspondence: Dr RL Roberts, Department of Pathology, University of Otago, PO Box 4345, Christchurch 8140, New Zealand. E-mail: rebecca.roberts@otago.ac.nz

Received 5 May 2008; Revised 28 May 2008; Accepted 30 May 2008; Published online 26 June 2008.

Abstract

Genome-wide association studies have identified PHOX2B, FAM92B, IRGM and NCF4 as candidate susceptibility factors for ileal Crohn's disease (CD). Here we sought to determine whether these genes were also associated with ileal CD in New Zealand Caucasians, as well as with ileocolonic CD, colonic CD and ulcerative colitis (UC). A total of 507 CD patients, 475 UC patients and 576 controls were genotyped for the single nucleotide polymorphisms rs16853571 (PHOX2B), rs4821544 (NCF4), rs13361189 and rs4958847 (IRGM), and rs8050910 (FAM92B). NCF4 and IRGM were significantly associated with ileal CD (P-value_rs4821544=0.0090, odds ratio (OR)=1.425, 95% confidence interval (CI): 1.092–1.859; P-value_rs13361189=0.0017, OR=1.942, 95% CI: 1.274–2.959; P-value_rs4958847=0.0022, OR=1.767, 95% CI: 1.224–2.558), but not with other forms of inflammatory bowel disease (IBD). No association of PHOX2B or FAM92B with IBD was detected. Our study has demonstrated that IRGM and NCF4 are ileal-specific CD susceptibility factors in New Zealand Caucasians.