The relation between Vitamin D receptor gene fokI polymorphism and degeneration of the temporomandibular joint

Objective: Predisposition to temporomandibular joint internal derangement (TMJ-ID) and osteoarthritis of the joint (TMJOA) might be related to genetic variations. Vitamin D receptor (VDR) gene polymorphisms are the candidates for association with the disorder. The aim of this study was to evaluate whether VDR FokI polymorphism is associated with the degeneration of the temporomandibular joint by gender. M e t h o d s : The study included 58 unrelated TMJ-ID patients (32.07 ±8.1) and 71 healthy controls (28.28 ±5.95) without TMJ-ID. DNA extraction was achieved by standard proteinase K/phenol-chloroform method from the blood samples. VDR gene FokI polymorphism was investigated by a polymerase chain reaction (PCR) based restriction fragment length polymorphism (RFLP) assay. Results: The genotype distributions of FokI (rs2228570, C>T) showed statistically significant results (p=0.026, χ2=7.2). Ff heterozygote genotype was statistically different as compared to FF genotype (OR=0.43, 95% CI: 0.2-0.92, p=0.028). Heterozygote Ff genotype was different comparing to the FF genotype in TMJ-ID women (OR=0.43, 95% CI: 0.16-1.10, p=0.07). Although the difference between ff and FF genotype were not different, ff genotype was a 2.77 fold risk factor (95% CI:0.29-26.03, p=0.37). The distributions of F and f alleles were not different between the groups of overall TMJ-ID vs. controls and women TMJ-ID vs. controls. Conclusion: The results of this study suggested that FokI polymorphism might present susceptibility to TMJ-ID/TMJOA. ff genotype might be associated with the degeneration of temporomandibular joint in TMJ-ID patients and TMJ-ID women