Clinical symptoms, biochemistry, and liver histology during the native liver period of progressive familial intrahepatic cholestasis type 2.

"Declarations Ethics approval and consent to participateThis study was approved by the institutional review boards at Juntendo University Graduate School of Medicine, The University of Tokyo, Osaka University Graduate School of Medicine, Yamaguchi University Graduate School of Medicine, Kyoto University Hospital, Saiseikai Yokohama City Eastern Hospital, University of Tsukuba Hospital, and National Center for Child Health and Development and performed by the amended Declaration of Helsinki and its later amendments or comparable ethical standards (as revised in Edinburgh 2000). We obtained informed consent in written form from patients’ parents or provided opportunities for refusal to participate in this study by opt-out. The participating medical institutions disclosed the opt-out document approved by the ethics committee. Consent for publicationNot applicable. Competing interestsHiroki Kondou has received NaPB as a gift from OrphanPacific, Inc. for an ongoing clinical trial (UMIN000024753). The other authors declare that they have no conflicts of interest. Competing interests Hiroki Kondou has received NaPB as a gift from OrphanPacific, Inc. for an ongoing clinical trial (UMIN000024753). The other authors declare that they have no conflicts of interest."

"Funding This work was supported by Grants JP17ak0101036 and JP19ek0109298 from the Japan Agency for Medical Research and Development to HH. The authors confirm independence from the sponsors; the sponsors have not influenced the content of the article."