The project has the following general aims: 1. Natural course and prognosis: To prospectively follow the natural course and prognosis of the different types of PFIC, to broaden the understanding of the different very rare diseases and to allow predictions about the course of disease in different types of PFIC. 2. Efficacy: To define the course of disease in FIC patients and identify associations with different treatments (symptomatic treatments, interruption of the enterohepatic circulation by surgical or medical means and other therapies such as corrector/potentiator or exon skipping therapy. The course of disease will be characterized by biochemical, clinical and surgical parameters, including liver transplantation. 3. Safety: To define the complications associated with the different treatments (symptomatic treatments, interruption of the enterohepatic circulation by surgical or medical means and other therapies such as corrector/potentiator or exon skipping therapy, liver transplantation). Follow up will be as long as possible. 4. (Surrogate) biomarker response: Biochemical parameters will be longitudinally collected and associated with changes in treatments / course of disease. 5. Genotype-phenotype relationships: If patient numbers permit, to establish genotype-phenotype relationships for (non)responsiveness towards different treatments in patients with genetic mutations causing the different forms of FIC disease.