Catechol-O-Methyltransferase Gene Variant is Associated With TMD Pain

Objectives: To explore the effects of single nucleotide polymorphisms (SNPs) in catechol-O-methyltransferase (COMT) as candidate gene for pain symptoms in temporomandibular disorders (TMD).

Methods: A total of 90 patients with pain-related TMD diagnosis and 92 matched controls were enrolled. Presence of TMD and chronic TMD pain was assessed by Research Diagnostic Criteria for TMD (RDC/TMD). Three single nucleotide polymorphisms (SNPs) spanning the COMT gene (rs4680, rs6269, and rs165774) were genotyped from peripheral blood DNA by Real-time Taq-Man method.

Results: Homozygous genotype AA and variant A allele carriers (AG/AA) for rs165774 polymorphism showed increased risk of TMD compared to wt genotype (Odds Ratio (OR=9.448, CI=1.913-46.652, p=0.006; OR=2.088, CI=1.138-3.829, p=0.017, respectively). AA genotype of rs165774 was related to higher chronic pain grade (p=0.037) and associated with increased risk of chronic TMD pain compared to wild type genotype (GG). (OR=6.173, CI=1.565-24.353, p=0.009). For pain scale measures tested in this study, the relation of SNP rs165774 with worst and average pain intensity was observed (p=0.021, p=0.007, respectively). Other COMT SNPs showed no evidence of a relation to TMD pain.

Conclusions: AA genotype of rs165774 could be a significant risk factor for the development of TMD pain.