Lack of common NOD2 variants in Japanese patients with Crohn's disease

Previous studies have linked Crohn's disease (CD) to the pericentromeric region of chromosome 16 (IBD1). Three independent studies of Western populations have recently shown that 3 variants of NOD2, a gene located at 16q12, are associated with susceptibility to CD. Here, we have evaluated the 3 NOD2 variants in Japanese patients to determine whether the gene is also associated with susceptibility to CD in a non-Western population.

Blood samples were obtained from 350 patients with CD, 272 patients with ulcerative colitis, and 292 healthy controls at 3 hospitals in Japan. DNA was sequenced in the region of the 3 NOD2 variants (C2104T in exon 4, G2722C in exon 8, and 3020insC in exon 11) by genomic polymerase chain reaction followed by direct sequencing.

Among the subjects in our 3 study groups, including patients with CD, patients with ulcerative colitis, and healthy controls, none had common NOD2 variants that have been associated with CD in white patients.

These results indicate that genetic variation, which may predispose some human populations to CD, may not be present in other populations and specifically that common variants in NOD2 found in white patients with CD are not associated with CD in the Japanese population.