If you agree to take part in this study, you will complete 5 questionnaires during a regularly scheduled clinic visit. These questionnaires will measure pain and other symptoms, such as your mood and quality of life. You will also be asked to give a tissue sample by inserting a swab into your mouth and rubbing firmly against the inside of your cheek or underneath your lower or upper lip for about a minute at most. Completing the 5 questionnaires and the swab sample collection takes about 30 minutes in total.