Additional Study Information: This study is evaluating how well odevixibat, an approved medication for Alagille Syndrome (ALGS), works in real-world clinical practice and how safe it is for long-term use. Participants with ALGS who are receiving odevixibat as part of their usual medical care will be followed for about five years. During this time, information from routine clinic visits will be collected to understand how treatment affects liver health, growth, and development, and to identify any side effects. This research may help improve care and future treatment options for people living with ALGS. If you have any questions regarding this study, please contact the Transplant Clinical Research Center (TCRC).