Figure 1: Statistically significant (higher) production of cytokines (unstimulated and stimulated by bacteria) on alleles of IL-4 SNP genes for patients with periodontitis () and healthy controls (), evaluation by Spearman rank correlations. Remark: our application of Spearman correlation analysis gives us the very similar results in comparison with levels of significance observed by K-W method with preliminary aggregation of two adjacent minority alleles (see legend under Table 3); application of Spearman rank correlations does not reduce any data and slightly more supports the hypotheses related to expression of cytokines on homozygous allele.