Session Title: Pediatric Rheumatology - Pathogenesis and Genetics
Session Type: Abstract Submissions (ACR)
A role for vitamin D has been hypothesized in generating disease activity for patients with juvenile idiopathic arthritis (JIA): specific polymorphisms of vitamin D receptor (VDR) gene have recently been associated with different biologic response to vitamin D itself.
To evaluate VDR polymorphisms in patients with JIA in comparison with unrelated healthy controls.
We recruited 81 Italian children, adolescents and young adults with JIA (mean age 20.21 + 7.11 SD, 67 female and 14 males, female/male ratio 4.79). After informed consent, during routine laboratory tests their genomic DNA was extracted from peripheral blood leukocytes, to analyze VDR polymorphisms by PCR-based sequencing (CDX2 in the promoter region) and PCR-based enzymatic digestions (FokI in exon 2, BsmI and ApaI in intron 8, and TaqI in exon 9). An Italian population of 2221 unrelated individuals without JIA was used as healthy controls.
The distribution of FokI, BsmI, ApaI, and TaqI polymorphisms did not show significant differences between children with JIA and controls. Regarding the CDX2 polymorphism, we observed a statistical difference in the distribution of GG and GA genotypes, with the GG genotype more frequent in JIA subjects (Yates-corrected chi-square 6.64; Odds ratio=1.87; p=0.01) and the GA genotype in healthy controls (Yates-corrected chi-square 4.47; Odds ratio=0.58; p=0.035). Data about AA genotype were not significant due to their very low number (five) within the JIA population. G allele resulted to be more frequent in JIA subjects (Yates-corrected chi-square 5,64; Odds ratio=1.61; p=0.017).
Pathogenetic mechanisms influencing the predisposition to JIA are poorly elucidated. Our analysis of CDX2 polymorphisms (located in the promoter region of the VDR gene) has revealed that both GG genotype and G allele are more represented in patients with JIA. We can speculate that the G allele decreases VDR transcriptional activity with respect to the A allele, as well as the presence of GG genotype could explain a reduction of VDR activity, with subsequent decreased response to vitamin D and potential immunity deregulation leading to JIA.
M. Matucci Cerinic,
M. L. Brandi,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/vitamin-d-receptor-polymorphisms-in-a-cohort-of-italian-patients-with-juvenile-idiopathic-arthritis/