Study Sheds Light on Gene Variations in Crohn's Disease

Polymorphisms may contribute to disease susceptibility

FRIDAY, Dec. 30 (HealthDay News) -- Two gene polymorphisms in a region of chromosome 5 previously linked to inflammatory bowel disease may be important for Crohn's disease susceptibility, according to a report in the December issue of Gastroenterology. The genetic variations are not independently linked to the disease, however, suggesting other mutations are lurking in this region of the genome.

Jack Satsangi, D.Phil., FRCP, from the Western General Hospital, University of Edinburgh in Scotland, and colleagues screened 374 patients with Crohn's disease, 305 with ulcerative colitis, and 294 healthy controls for genetic variations at five different sites within the IBD5 locus. They specifically looked at polymorphisms in the organic cation transporter (OCT) genes 1 and 2, which are found in the IBD5.

The authors found the variant allelic frequency was higher in Crohn's disease patients than controls for OCTN1 polymorphisms (53.6% versus 43%) and OCTN2 (56.1% versus 48.4%). Crohn's patients were more likely to be homozygous for the OCTN1/2-TC haplotype (28.4% versus 16%) than healthy controls. However, without the IBD5 risk haplotype, the variations were no longer associated with Crohn's disease.

"The IBD5 locus influences susceptibility, progression, and need for surgery in Crohn's disease," the authors conclude. "However, the contribution of OCTN1/2 variants is not independent of the IBD5 haplotype; a causative role for these genes remains plausible but is not yet proven. Further genetic, functional, and expression data are now required."

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