Only after subjects have consented to participate in the study will the screening procedures commence. All subjects recruited in this study will have already consented to the pharmacogenomics in ethnically diverse populations (SOPHIE) study, a previously established cohort of healthy people living in San Francisco. A review of the subject's medical history and health questionnaire will be conducted to re-assess health status and confirm eligibility (see attached health questionnaire). Changes in medication or drug use history will be noted during the study.