Association of vitamin D receptor BsmI rs1544410 and ApaI rs7975232 polymorphisms with susceptibility to adolescent idiopathic scoliosis: A systematic review and meta-analysis

BACKGROUND: AIS is the most common spinal deformity disease, yet its etiology remains uncertain. Significant associations have been found between AIS risk and vitamin D receptor (VDR) gene polymorphisms; however, some of these results are controversial. The aim of this study was to determine whether VDR BsmI rs1544410 and ApaI rs7975232 polymorphisms are correlated with AIS. METHODS: Databases, including PubMed, EMBASE, Web of Science, the Cochrane Library, the Chinese Biomedical Literature Database, and the Wanfang Database, were systematically searched, and eligible case–control studies that explored the association of VDR (BsmI and ApaI) and the susceptibility to AIS were selected. The pooled odds ratio (OR) with 95% confidence interval (95% CI) was calculated to assess the associations, and subgroup meta-analyses were performed according to the ethnicity of the study population. RESULTS: A total of 5 studies with 717 cases and 554 controls fulfilled the inclusion criteria after assessment by 2 reviewers. Generally, significant correlations were found between the BsmI polymorphism and AIS risk in overall populations and in Asian populations (overall population: B vs b: OR = 2.12, 95% CI = 1.21–3.75, P = .009; BB vs bb: OR = 3.38, 95% CI = 1.08–10.57, P = .036; Bb vs bb: OR = 2.50, 95% CI = 1.29–4.82, P = .006; BB/Bb vs bb: OR = 2.71, 95% CI = 1.31–5.63, P = .007; Asian population: B vs b: OR = 2.42, 95% CI = 1.27–4.61, P = .007; BB vs bb: OR = 4.09, 95% CI = 1.03–16.22, P = .045; Bb vs bb: OR = 2.94, 95% CI = 1.42–6.10, P = .004; BB/Bb vs bb: OR = 3.23, 95% CI = 1.42–7.35, P = .005). There was no significant association observed in Caucasian populations (all P > .05). With regard to the ApaI polymorphism, we found that it significantly decreased the risk of AIS (Aa vs AA: OR = 0.43, 95% CI = 0.24–0.77, P = .004; Aa/aa vs AA: OR = 0.52, 95% CI = 0.30–0.91, P = .023); however, we could not draw a definitive conclusion for Caucasian populations, as no studies have been conducted in this group to determine the role of the VDR ApaI polymorphism in AIS etiology and development. CONCLUSION: VDR BsmI was significantly associated with AIS susceptibility in the overall and Asian populations, while the VDR ApaI polymorphism only played a key role in AIS etiology and development in Asian populations.