New research has shown one of the genes that increases the likelihood of development of chronic pain. COMT (Catechol-O-methyl transferase) enzyme degrades catecholamines such as dopamine, epinephrine, and norepinephrine in our brain and there are multiple variants of this enzyme. COMT is associated with pain responsiveness and contains some combination of amino acids valine and methionine. People can be categrorized into met/mets or val/vals or a combination. Val/vals have more valine and degrade dopamine very quickly (about 4x faster than met/mets). This has the effect of dampening pain perception. Met/mets are more sensitive to pain and thus more likely to develop chronic pain syndromes. They may also play some unknown role in violent behavior (research is ongoing).
Genetic studies have shown COMT and HTR2A are associated with TMD chronic pain Smith JPain 2011 Nov
Those with COMT variant that increases pain perception are more likely to develop TMD post orthodontics. This may lead to eventual genetic screening prior to orthodontic care to better inform specific individuals of their heightened or lowered risk for development of post-orthodontic TMD. Slade Semin Orthod. 2008 Jun = good article especially the Genetic influence on TMD risk section.