Long-Term Low-Intervention SafEty and Clinical Outcomes Clinical Study of LivmArli® in Patients With Alagille Syndrome or Progressive Familial Intrahepatic Cholestasis in the European Union (LEAP-EU)

Inclusion Criteria: * Understand and execute an Informed consent and assent (as applicable) * For participants with ALGS ≥2 months of age at Day 1 * For participants with PFIC, ≥3 months of age at Day 1 * A clinically and/or genetically confirmed ALGS diagnosis with pruritus secondary to chronic cholestasis, or a clinically and/or genetically confirmed PFIC diagnosis * For the ALGS primary cohort: Initiation of Livmarli at the time of study entry * For the ALGS supplemental cohort, : Actively using Livmarli prior to study entry * For participants with PFIC: Prescribed Livmarli at the time of study entry or prior to study entry Exclusion Criteria: * History of Liver Transplant * Any Livmarli contraindications (as per SmPC) * Any condition or abnormality that, in the opinion of the investigator, may interfere with the participation in or completion of the study * Received an investigational drug within 30 days before the first dose of Livmarli (Participation in previous maralixibat studies or expanded-access programs is acceptable.) * Received another IBAT inhibitor within 7 days before the first dose of Livmarli * Baseline data before start of treatment of Livmarli are unavailable (\<2 values before treatment) for key safety (LFTs, FSV laboratory results) and key efficacy (sBA, pruritus) parameter