**2.3 Interleukin-10**

It is an anti-inflammatory cytokine expressed by T helper cells. It is encoded on gene at 1q31-q32. The major regions of interleukin-10 single nucleotide polymorphisms studied were −1082, −819, and −592. However, conflicting results have been obtained. Berglundh et al. found positive associations between IL-10 SNP and periodontitis in Swedish and Brazilian population [14]. Scarel-Caminaga et al. did not find any significant association in the Caucasian population [15].
