Liver function tests in PFIC2 patients (Patients 1 and 2) before and during the course of NaPB therapy. Patients 1 and 2 underwent NaPB therapy as described in the Methods. Serum T-Bil, D-Bil, TBA, AST, ALT, and GGT levels were monitored. The dosage and regimen of NaPB administration during the course of therapy is shown at the top. Closed triangles represent times when a liver biopsy was performed. The number at the upper right of the triangles corresponds to that of age in Fig. 6. RIF, rifampicin; TBA, total bile acids.