Cross-sectional data from the population-based Study of Health in Pomerania (SHIP) in Germany were used to estimate additive interactions between depressive symptoms and 22 single-nucleotide polymorphisms (SNPs) of the COMT gene and the neighbouring thioredoxin reductase 2 (TXNRD2) gene on TMD pain.
Forty Caucasian female participants meeting the Research Diagnostic Criteria for TMD were genotyped for COMT polymorphisms and completed a randomized, double-blind, placebo-controlled, two-period crossover pilot study.
Recently, our group demonstrated that three common haplotypes of the human COMT gene, divergent in two synonymous and one nonsynonymous position, are associated with experimental pain sensitivity and onset of temporomandibular joint disorder.
Results show that the COMTrs4680 (rs4680;s4680;rs1200746244" genes_norm="1312;4524">val(158)met) polymorphism is most strongly associated with outcome measures, such that individuals with the minor A allele (met) exhibit reduced COMT activity, increased TMD risk, and increased musculoskeletal pain.
Polymorphisms in COMTrs4818 were significantly associated with myofascial pain (OR<sub>c</sub> = 2.15; CI 95%: 1.08-4.29; P = 0.02) and were borderline for painful TMD (OR<sub>c</sub> = 1.85; CI 95%: 0.97-3.51; P = 0.06) and disc displacement (OR<sub>c</sub> = 2.42; CI 95%: 1.00-5.87; P = 0.05).
Our data extend the number of SNPs present in the promoter region that could play a regulatory role in COMT gene and suggest that the genetic polymorphisms rs 165656 and rs 4646310 exert a role in TMD susceptibility.
Unexpectedly, the pathological loss of M-band titin due to TMD/LGMD2J mutations was found to be independent of CAPN3, whereas the involvement of ubiquitous calpains is likely.
These results imply that titin mutations may be responsible for TMD, and that the pathophysiologic pathway following calpain3 deficiency may overlap with LGMD2A.
Then, since the introduction of a proline in the last domain of titin was previously known to cause TMD in French families, we can conclude that this missense mutation is the obvious pathogenetic mutation in the affected patients.
A novel A-band titin mutation, c.92167C>T (p.P30723S), was found in 1 patient, and 1 Portuguese patient with a severe TMD phenotype proved to be homozygous for the previously reported Iberian TMD mutation.
Studies have already pointed the association between TMD and genetic polymorphisms in the oestrogen receptor alpha, adrenergic receptor beta 2, serotonin receptor, serotonin transporter and catechol-O-methyltransferase genes, and other candidate genes continue to emerge.
<b>Objective:</b> To evaluate if temporomandibular disorders (TMDs) are associated with genetic polymorphisms in <i>ESR1</i> and <i>ESR2</i>, which are genes encoding oestrogen receptor alpha (<i>ERα</i>) and beta (<i>ERβ</i>).