[Association between interleukin-1 composite genotype and severe periodontitis: case-control study]

Interleukin-1 (IL-1) is a bone resorption stimulating cytokine that is implicated in the development of periodondal lesions. Recent studies suggest that the production of this mediator depends for quantity on a specific allelic combination in its genetic cluster. Periodontitis severity was correlated with the extent of the form 2 allele at the position -889 in the gene IL-1A, together with the form 2 allele at the position +3953 of the gene IL-1B. Aim of the study was to evaluate the relationship between the prevalence of the previously mentioned composite genotype and severity of periodontal lesions.

A group of 20 subjects aged more than 35 with clinical and radiographic signs of severe periodontitis (cases) underwent the salivary genetic test to single out the alleles of the genes IL-1A and IL-1B, by the PCR technique. The same test was performed to a group of 10 periodontally healthy people (controls) recruited by the same conditions. Excluding criteria were: smoking (actual or past), systemic diseases, drug absumption.

Only 7/20 patients of the case-group were positive for the composite genotype (Allele 2 of both the genes IL-1A and IL-1B), consisting in the 35% of the group. In the control-group, 4/10 subjects were positive (40%). In the case group it was not possible to underline any difference in clinical signs between positive and negative patients (respectively: Mean Probing Depth 5.05 mm vs 5.27 mm; Full Mouth Bleeding Score 56.43% vs 43.33%; Full Mouth Plaque Score 49.7% vs 41.75%)

The results obtained lead us to consider of little value the meaning of this genetic test. The test did not supply any useful element in discriminating controls from severe periodontal cases; therefore, it is not useful in the formulation of the prognosis.