COMT and temporomandibular joint disorder: For example, an A to G synonymous SNP at a Leu codon, present in the coding region of the catechol-O-methyltransferase (COMT) mRNA, was identified in subjects with high pain sensitivity and at greater risk of developing temporomandibular joint disorder (Diatchenko et al., 2005; Nackley et al., 2006).