A meta-analysis suggests the association of reduced serum level of vitamin D and T-allele of Fok1 (rs2228570) polymorphism in the vitamin D receptor gene with celiac disease.

Purpose: As an immune-modulator, vitamin D is known to regulate immune response and is implicated in disease pathogenesis. Celiac disease (CD) is a systemic autoimmune disease and susceptibility conferred by vitamin D metabolism is under investigation. Studies on the association of vitamin D metabolism and genetic polymorphisms are expected to explain CD pathogenesis. We performed a systematic review-based meta-analysis to investigate the 25(OH)D serum levels and susceptibility conferred by the genetic variants of VDR in CD.

Methods: Systematic review was conducted through a web-based literature search following stringent study inclusion-exclusion criteria. The Newcastle-Ottawa Scale and GRADE tools were used to assess the quality of evidence in studies and the study outcome. Cohen's κ value was estimated to access the reviewer's agreement. RevMan 5.4.1 was used to perform the meta-analyses. Weighted mean difference and Meta -value was assessed for 25(OH)D serum levels. Meta-odds ratio and -test -value were evaluated to estimate the allelic susceptibility of variants.

Results: A total of 8 out of 12 studies were evaluated for "25(OH)D" serum level, while four studies were found eligible for SNPs (, and ) of . Significantly higher levels [WMD = 5.49, < 0.00001] of 25(OH)D were observed in healthy controls than in patients with CD. rs2228570-T () [Meta-OR = 1.52, = 0.02] was confirmed to be predisposing allele for CD.

Conclusion: Reduced serum level of 25(OH)D and association of T-allele of confirmed in this study plays a critical role in immunomodulation and maintaining barrier integrity, which is majorly implicated in CD.