One hundred ninety six (196) healthy European American pain-free females with an age range of 18–34 years were genotyped and phenotyped. Demographic characteristics of the cohort at the time of recruitment were previously described (47). This study was nested within a larger prospective study conducted at the University of North Carolina at Chapel Hill, which was designed to examine whether pain sensitivity is a risk factor for the development of TMJD (47). Subjects were phenotyped with respect to their sensitivity to pressure pain, heat pain and ischemic pain. Indices of the temporal summation of heat-evoked pain were also examined. The detailed description of phenotypic procedures can be found in Supplementary Materials. Each enrollee in the analyzed cohort was quantified for responsiveness to a set of 16 noxious stimuli applied to various anatomical sites.
