Influence of Genetics in Pain Sensitivity

Variability in pain sensitivity is a well known phenomena. Clinicians involved in the care of post-surgical patients are very familiar with this variation in sensitivity. The variability also extends to experimental pain stimuli (e.g., a thermal pulse to the forearm) and can be demonstrated with normal volunteers. In our clinic, variation in the intensity and onset of acute pain in the oral surgery model, in subjects matched for similar levels of tissue injury ranges from little or no post-operative pain to reports of severe pain unrelieved by standard analgesics. While a variety of factors may account for the variability such as race or gender (Gordon 1998), preclinical data indicate that genetic factors profoundly influence pain sensitivity. Thus, the proposed study seeks to investigate genetic contributions to acute experimental and clinical post-operative pain. We have recently shown a strong correspondence between pain reports using thermal heat stimuli and post-operative pain reports. This observation has given us an important quantitative screening tool for genetic analysis of a moderate-sized cohort of subjects that has direct clinical relevance. Normal subjects and their siblings and/or parents will undergo two somatosensory tests to determine pain phenotype and will provide a blood sample which will be analyzed for genetic polymorphisms contributing to sensitivity to pain. Some of these subjects will also be candidates for the oral surgery protocol and similar pain ratings will be obtained from them post-operatively. The initial study will examine known polymorphisms for candidate genes that code for pain sensing and pain suppressing molecules.