MedWire News: Variants in the vitamin D receptor (VDR) gene are linked to bone mineral density (BMD) in patients with the inflammatory bowel disease, ulcerative colitis (UC), research suggests.
The findings also indicated that the influence of VDR genotype on BMD varied by gender, but the study authors warn that their data should be considered preliminary and interpreted with caution.
“Despite hundreds of association studies and retrospective meta-analyses of polymorphisms in more than 30 genes that are associated with BMD and fractures, no convincing conclusions have emerged,” write Wojciech Pluskiewicz (Medical University of Silesia, Katowice, Zabrze, Poland) and co-authors.
“The VDR polymorphism is no exception, and understanding the pathogenesis of osteoporosis will require revealing several different aspects, also including genetic investigations.”
In their study, Pluskiewicz and colleagues investigated BMD in subjects with UC with respect to disease extent and severity and VDR polymorphisms.
A total of 47 patients with UC were matched for age and gender with 47 healthy individuals. Among cases, the average disease duration was 8.6 years and disease severity was mild, moderate, and severe in 24, 17, and five patients, respectively.
Writing in the Journal of Bone and Mineral Metabolism, Pluskiewicz et al report that mean BMD at the spine did not differ significantly between cases and controls.
However, spine BMD was lower in patients with moderate/severe UC than in patients with mild disease, and lower in patients with disseminated intestinal changes than in those with local changes.
Most interestingly, spine BMD varied by VDR genotype in cases but not controls, and the effect differed by gender. In men with UC, the bb genotype was less strongly associated with low BMD than other genotypes, whereas in women with UC, the VDR tt genotype was more strongly associated with low BMD.
The researchers say that this is the first study to show an association between VDR polymorphisms and BMD in patients with UC, but add: “The current results should be treated as preliminary and further studies are warranted.”
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