Thoracic (heart and/or lung) transplantation is an effective but aggressive measure for treatment of end-stage heart and lung diseases. However, rejection of the transplanted organ remains a major problem and frequently leads to organ loss and death. All transplant recipients take immunosuppressants (drugs that prevent rejection), yet over-immunosuppression exposes them to undesirable infections and other side effects. Mycophenolic acid (MPA) is an effective immunosuppressant commonly used in transplantation. However, tailoring MPA therapy is challenging due to the wide variability and unpredictability in treatment responsiveness and side effects among patients. Genetic makeup and metabolism of MPA have a significant bearing on drug responsiveness. While many studies provide better understanding of MPA in kidney transplant recipients, information on the thoracic transplant population is scarce. Lillian Ting’s research is exploring the role of genetics in determining treatment responses. The ultimate goal is to individualize regimens, even before treatment begins, for each patient in order to obtain optimal treatment response and minimal toxicity. The results from Lillian’s study will add valuable knowledge to transplantation management. It will be directly incorporated into patient care, improving patient survival and quality of life after transplantation.