Why do some people suffer with long term pain after an accident or surgery whilst another person recovers without incident? We believe that part of the answer lies in the subtle differences in people's genes. We are interested in how these little differences can add up to make an individual more or less likely to suffer from pain. Unfortunately we don't know at the moment which gene differences are important. We plan to invite people, from the ALSPAC cohort, with known common variants in a specific gene that has been linked to pain detection (TRPA1), to come for testing of their sensitivity to mildly painful stimulation. If we find people who have differences in their pain sensitivity, we will invite them back for more detailed tests. In these detailed tests, we will record the activity in their nerves during mildly painful stimulation to see if a change in their nerve activity underlies their differences in pain sensitivity.

The mildly painful stimulation that we use is well tolerated by both patients and volunteers. Most of our tests look at pain "threshold" e.g. the transition from warm to hot. We therefore use the lowest temperature that causes pain to be perceived. We will also ask participants to rate how much pain they feel in response to a given stimulus. We believe that these tests are less painful then giving blood or a skin biopsy. The participant can stop the experiment at any time if it is too uncomfortable.