Interleukin-1 Two-Locus Haplotype Is Strongly Associated with Severe Chronic Periodontitis among Yemenis

Abstract EN

Aim.

To assess IL-1A C[−889]T and IL-1B C[3954]T genotypes as well as haplotypes in relation to sever chronic periodontitis (SCP) among Yemenis.

Materials and Methods.

40 cases with SCP and 40 sex- and age-matched controls were included; all were nonsmokers and free of systemic diseases.

Genotyping at each locus was performed using an established PCR-RFLP assay.

The Haploview and SimHap software were used to assess data for Hardy-Weinberg's equilibrium (HWE) and linkage disequilibrium (LD) and to obtain subject-level haplotypes.

Multiple logistic regression was used to seek for associations in dominant, additive, and recessive models.

Results.

Mean plaque index (MPI) showed the strongest association with SCP (OR=16).

A significant LD was observed in the cases (D'=0.80 and r2=0.47).

The genotype at each locus showed significant association with SCP in the recessive model (TT versus TC+CC) even after adjustment for MPI (OR=6.29 & 461, resp.).

The C-T haplotype conferred protection against SCP in a dominant manner (OR=0.16).

On the other hand, the T-T haplotype in double dose (recessive model) showed strong association with CP (OR=15.6).

Conclusions.

IL-1 two-locus haplotype is associated with SCP in Yemenis.

Haplotype-based analysis may be more suited for use in genetic association studies of periodontitis.