Characterization of urinary bile acids in a pediatric BRIC-1 patient: Effect of rifampicin treatment

Background: Benign recurrent intrahepatic cholestasis type 1 (BRIC-1), a rare autosomal recessive disorder characterized by recurrent episodes of jaundice and pruritus, is caused by mutations in the ATP8B1 gene. Rifampicin has been reported to be an effective treatment of jaundice and pruritus in patients with BRIC. Proposed mechanisms of effect for rifampicin include enhancement of multidrug-resistance protein 2 expression, activation of the enzymes of uridine diphosphate glucuronosyltransferase 1A1 and cytochrome P450 3A4, and stimulation of 6 alpha-hydroxylation of bile acids. Methods: To confirm the diagnosis of BRIC-1 and demonstrate the effect of rifampicin treatment on bile acid metabolism, we analyzed the patient's ATP8B1 gene and bile acids in urine. Results: We detected 2 heterozygous mutations in the ATP8B1 gene, and increasing amounts of unusual bile acids such as 1 beta-hydroxylated cholic acid, 2 beta-hydroxylated cholic acid, 4 beta-hydroxylated cholic acid, 6 alpha-hydroxylated cholic acid, and hyocholic acid in urine during rifampicin treatment. Conclusions: We diagnosed a jaundiced pediatric patient with BRIC-1 caused by 2 novel mutations (1226delA/2210delA) in the ATP8B1 gene. Rifampicin was effective in treating cholestasis. Results of urinary bile acid analyses during rifampicin treatment in this patient, suggested that rifampicin might stimulate 1 beta-, 2 beta-, and 4 beta-hydroxylation of bile acids in addition to 6 alpha-hydroxylation. (C) 2012 Elsevier B.V. All rights reserved.