Interleukin-1 Two-Locus Haplotype Is Strongly Associated with Severe Chronic Periodontitis among Yemenis.
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 r(2) = 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.
Molecular Research Laboratory, Faculty of Medical Sciences, University of Science and Technology, Sana'a, Yemen.
Nezar Noor
NN
Al-Hebshi
Amat-Alrahman Ahmed
AA
Shamsan
Mohammed Sultan
MS
Al-Ak'hali