VDR and polycystic ovary syndrome: VDR-SNP: Vitamin D receptor-single nucleotide polymorphism, rs: Reference SNP cluster ID, OR: Odds ratio, PCOS: Polycystic ovary syndrome, EMRO: Eastern Mediterranean Regional Office. I-squared-based Q statistics were used to evaluate the inter-study heterogeneity, wherein the fixed model was applied for conditions with no significant heterogeneity. Begg funnel plot and Egger's linear regression test were used to evaluate possible publishing bias. The pooled OR with 95% CI was calculated for the strength of the associations. Two-sided p-values < 0.05 were regarded as statistically significant