Association between single nucleotides polymorphisms in the DR2D, ANKK1, COMT, and 5-HTT genes with temporomandibular disorder

Background  Temporomandibular disorders (TMDs) comprise a heterogeneous group of musculoskeletal conditions affecting the temporomandibular joint, masticatory muscles, and associated structures. Growing evidence highlights the role of genetic predisposition as a significant contributor to TMD.

Aim  This study aimed to investigate genetic aspects involved in TMDs etiology.

Methodology  A cross-sectional study was conducted with 249 adolescents, of whom 149 were affected by TMD. Genomic DNA was extracted from buccal cells, and single nucleotide polymorphisms (SNPs) in DRD2 (rs6275 and rs6276), ANKK1 (rs1800497), COMT (rs6269 and rs4818), and 5-HTT genes (rs3813034 and 1042173) were analyzed. Allelic and genotypic distribution, haplotype, and diplotype analysis were performed using PLINK software version 1.06. Multifactor dimensionality reduction (MDR) was applied to identify SNP-SNP interactions and generate an interaction graph.

Results  In total, three possible single-locus allele combinations were obtained for haplotype and diplotype analyses (rs6275|rs6276 in DRD2, rs6269|rs4818 in COMT and rs3813034|rs1042173 in 5-HTT), but no associations with TMD were observed (p>0.05). However, MDR analysis for gene-gene interactions revealed a synergistic relationship between rs6275 (DRD2), rs6269 (COMT), and rs1042173 (5-HTT) that predisposes to TMD (p=0.050).

Conclusion  MDR analysis suggests a possible synergistic interaction among SNPs in the DRD2, COMT, and 5-HTT genes that may contribute to TMD susceptibility in adolescents.

Keywords
Genetic polymorphisms; Orofacial pain; Temporomandibular joint disorders; Serotonin; Dopamine