VNTR of IL-1RN gene polymorphism and gingivitis in children

Background: IL-1Ra is an anti-inflammatory cytokine, which is able to block the actions of IL-1. The IL-1RN*2 allele is thought to be associated with IL-1Ra production. There are no studies on the role of IL-1RN gene polymorphism in gingivitis in children. Objectives: To investigate the association between a polymorphism of a variable numbers of tandem repeats (VNTR) of inetrleukin-1 receptor antagonist gene (IL-1RN) and gingivitis in children. Materials and Methods: A total of 164 Caucasian subjects (107 subjects with gingivitis and 57 controls) aged 8-12 years old, were enrolled. Plaque and Calculus Indices were recorded to assess the oral hygiene. Gingival and Bleeding on Probing Indices were used to identify patients with gingivitis. DNA was extracted from epithelial cells of the cheek. Normal polymerase chain reaction was used for IL-1RN genotyping. Results: The IL-1RN* 2 allele (A2) seems to be a protective marker against gingivitis as it was significantly more frequent in controls than children with gingivitis(37% vs 22% respectively, P=0.009). In addition, severe gingivitis was also less frequent in IL-1RN*2 positive children (39% vs 61% in IL-1RN*2 negative children, P=0.039). Moreover, multiple logistic regression showed that the association between IL-1RN gene polymorphism and gingivitis in children remained significant (P=0.017) regardless of the significant influence of plaque (P=0.012). Conclusion: The IL-1RN* 2 allele could be a protective marker against gingivitis in children.