Polymorphisms in COMT, ADRB2 and HTR1A genes are associated with temporomandibular disorders in individuals with other arthralgias

Is catechol‐O‐methyltransferase gene associated with temporomandibular disorders? A systematic review and meta‐analysis

“…RDC/TMD criteria were the most used. 6,7,11,[14][15][16][17][18]20 One study used the physical method 13 and another just the Questionnaire of the American Academy of Orofacial Pain (AAOP). 17 Regarding the screening to recruit patients, only two articles report this information.…”

“…7,20 The TMD screening of patients before the examination was performed by the AAOP questionnaire in only one article, 17 and this information was not reported in nine articles. 6,7,11,[13][14][15][16]18,20 The DNA collection method was saliva/oral cells in four articles 11,13,[16][17][18] and blood in five articles. 6,7,14,15,20 The DNA analysis method varied between studies.…”

“…6,7,14,15,20 The DNA analysis method varied between studies. The genetic polymorphism rs4680 was evaluated in three articles, 11,13,17 whereas Bonato et al 16 evaluated the genetic polymorphisms rs9332377, rs6269, and rs165774. The genetic polymorphisms rs4818, rs4633, rs6269, and rs4680 were evaluated by Slade et al 20 Michelotti et al 14 evaluated more than 40 genetic polymorphisms in COMT, and Smith et al 15 evaluated the rs4680 among other 80 genetic polymorphisms.…”

“…Finally, the Hardy-Weinberg equilibrium for evaluated genotype distributions were performed only by Smith et al, 7 Serrano, 11 Michelotti et al, 14 Bonato et al, 16 and Tesch et al 18 Classification of TMDs varied among the studies. Three articles 11,13,14 assessed the presence and absence of the disorder, whereas three other articles [16][17][18] classified as myofascial pain, arthralgia, disk displacement, and painful TMD according to RDC criteria. In four articles, 6,7,15,20 they evaluated only the pain sensitivity.…”

“…9 A large number of the genetic polymorphisms in the COMT gene have been associated with emotional disorders, stress, 10 painful conditions, 2,6 and TMD. 7,[11][12][13][14][15][16][17][18] Some genetic polymorphisms in COMT have been associated with TMD, and some of them are located in non-coding regions of the gene (rs174697, 7 rs4669, 11 rs6269, 12,18 and rs9332377 14,18 ), in coding regions (rs4680 13,15 and rs4818 17 ), and in the promoter regions (rs4646310, rs165656, and rs165722 14 ). The most studied genetic polymorphism is rs4680, which causes an amino acid substitution in the enzymatic polypeptide chain resulting in lower thermostability and, consequently, less activity.…”