Evaluation of genetic risk related to catechol-O-methyltransferase (COMT) and β2-adrenergic receptor (ADRB2) activity in different diagnostic subgroups of temporomandibular disorder in Brazilian patients

The aim of this study was to evaluate the possible association between polymorphisms in the catechol-O- methyltransferase (COMT) and beta 2-adrenergic receptor (ADRB2) genes and muscular temporomandibular disorders (TMD). This was a case-control study. Individuals were evaluated using the Research Diagnostic Criteria for Temporomandibular Disorders and were divided into three groups: unaffected (no TMD) (n = 154); exclusively muscular TMD (n = 49); exclusively articular TMD (n = 49). Genomic DNA was obtained from saliva samples, and single nucleotide polymorphisms in the COMT (rs165774, rs6269, rs9332377) and ADRB2 ( rs2053044, rs1042713, rs1042714) genes were investigated. The TT genotype for the COMT rs9332377 gene was highly associated with the presence of muscular TMD (P = 0.03). With respect to the ADRB2 gene, the non-polymorphic AA genotype in the rs1042713 region was more prevalent in the articular TMD group than in the muscular TMD group (P = 0.05). This study supports the hypothesis that alterations in the COMT and ADRB2 genes influence the muscular pathophysiology.