Background-The vitamin D receptor (VDR) gene represents a strong positional
candidate susceptibility gene for inflammatory bowel disease (IBD). The VD
R gene maps to a region on chromosome 12 that has been shown to be linked t
o IBD by genome screening techniques. it is the cellular receptor for 1,25(
OH)(2) vitamin D-3 (calcitriol) which has a wide range of different regulat
ory effects on the immune system. IBD is characterised by activation of the
mucosal immune system.
Aim-To determine if polymorphisms in the VDR gene are associated with susce
ptibility to IBD Subjects-European Caucasoids: 158 patients with ulcerative
colitis, 245 with Crohn's disease, and 164 cadaveric renal allograft donor
controls.
Method-Single nucleotide polymorphisms (TaqI, ApaI, and FokI) in VDR were t
yped in patients with Crohn's disease, ulcerative colitis, and controls by
polymerase chain reaction with sequence specific primers.
Results-There were significantly more homozygotes for the TaqI polymorphism
at codon 352 of exon 8 (genotype "tt") among patients with Crohn's disease
(frequency 0.22) than patients with ulcerative colitis (0.12) or controls
(0.12) (odds ratio 1.99; 95% confidence interval 1.14-3.47; p=0.017).
Conclusion-This study provides preliminary evidence for a genetic associati
on between Crohn's disease susceptibility and a gene that lies within one o
f the candidate regions determined by linkage analysis.