Inflammatory bowel diseases (IBDs), Crohn's disease, and ulcerative colitis (UC), are multifactorial disorders, characterized by chronic inflammation of the intestine. A number of genetic components have been proposed to contribute to IBD pathogenesis. In this case-control study, we investigated the association between two common vitamin D-binding protein (DBP) genetic variants and IBD susceptibility. These two single nucleotide polymorphisms (SNPs) in exon 11 of the DBP gene, at codons 416 (GAT>GAG; Asp>Glu) and 420 (ACG>AAG; Thr>Lys), have been previously suggested to play roles in the etiology of other autoimmune diseases.
Using TaqMan SNP technology, we have genotyped 884 individuals (636 IBD cases and 248 non-IBD controls) for the two DBP variants.
On statistical analysis, we observed that the DBP 420 variant Lys is less frequent in IBD cases than in non-IBD controls (allele frequencies, P=0.034; homozygous carrier genotype frequencies, P=0.006). This inverse association between the DBP 420 Lys and the disease remained significant, when non-IBD participants were compared with UC (homozygous carrier genotype frequencies, P=0.022) or Crohn's disease (homozygous carrier genotype frequencies, P=0.016) patients separately. Although the DBP position 416 alone was not found to be significantly associated with IBD, the haplotype DBP_2, consisting of 416 Asp and 420 Lys, was more frequent in the non-IBD population, particularly notably when compared with the UC group (Odds ratio, 4.390).
Our study adds DBP to the list of potential genes that contribute to the complex genetic etiology of IBD, and further emphasizes the association between vitamin D homeostasis and intestinal inflammation.
[Show abstract][Hide abstract] ABSTRACT: Inflammatory bowel disease (IBD) has classically been associated with malnutrition and weight loss, although this has become less common with advances in treatment and greater proportions of patients attaining clinical remission. However, micronutrient deficiencies are still relatively common, particularly in CD patients with active small bowel disease and/or multiple resections. This is an updated literature review of the prevalence of major micronutrient deficiencies in IBD patients, focusing on those associated with important extraintestinal complications, including anemia (iron, folate, vitamin B12) bone disease (calcium, vitamin D, and possibly vitamin K), hypercoagulability (folate, vitamins B6, and B12), wound healing (zinc, vitamins A and C), and colorectal cancer risk (folate and possibly vitamin D and calcium). (Inflamm Bowel Dis 2012).
[Show abstract][Hide abstract] ABSTRACT: Vitamins are micronutrient chemical compounds that cannot be synthesized by an organism but are essential for human metabolism and life. They act as required intermediaries, cofactors or coenzymes in many of the reactions of normal metabolism. In addition, anti-inflammatory effects have been reported for specific vitamins. In inflammatory bowel disease (IBD), vitamin deficiency is often due to malnutrition (due to a decreased food intake) or malabsorption (due to inflamed, malfunctioning mucosa and diarrhea) which results in anemia. Vitamin B12 and folic acid supplementation may be necessary in IBD patients, especially those with Crohn's disease (CD) with either inflammation of the terminal ileum or after resection of the terminal ileum. It is also recommended during therapy with sulfasalazine as this compound inhibits the absorption of vitamin B12. Patients with high or continuous inflammatory CD activity and frequent therapy with steroids have an increased risk of low bone mineral density and vitamin D deficiency. These should be monitored regularly and vitamin D should be supplemented. In a recent trial, a trend towards a reduced risk of relapses in CD patients treated with vitamin D was reported. Only limited studies and case reports exist on other vitamin deficiencies, e.g. vitamins A, B1, B2, niacine, B 6, C, E and K, found in IBD patients. These are summarized in this review. Regular nutritional monitoring in IBD patients is warranted and requires the special attention of treating physicians and dieticians.
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