Genetic defects in bile acid conjugation cause fat-soluble vitamin deficiency

Kenneth D R Setchell, James E. Heubi, Sohela Shah, Joel E. Lavine, David Suskind, Mohammed Al-Edreesi, Carol Potter, David W. Russell, Nancy C. O'Connell, Brian Wolfe, Pinky Jha, Wujuan Zhang, Kevin E. Bove, Alex S. Knisely, Alan F. Hofmann, Philip Rosenthal, Laura N. Bull

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Abstract

Background & Aims: The final step in bile acid synthesis involves conjugation with glycine and taurine, which promotes a high intraluminal micellar concentration to facilitate lipid absorption. We investigated the clinical, biochemical, molecular, and morphologic features of a genetic defect in bile acid conjugation in 10 pediatric patients with fat-soluble vitamin deficiency, some with growth failure or transient neonatal cholestatic hepatitis. Methods: We identified the genetic defect that causes this disorder using mass spectrometry analysis of urine, bile, and serum samples and sequence analysis of the genes encoding bile acid-CoA:amino acid N-acyltransferase (BAAT) and bile acid-CoA ligase (SLC27A5). Results: Levels of urinary bile acids were increased (432 ± 248 μmol/L) and predominantly excreted in unconjugated forms (79.4% ± 3.9%) and as sulfates and glucuronides. Glycine or taurine conjugates were absent in the urine, bile, and serum. Unconjugated bile acids accounted for 95.7% ± 5.8% of the bile acids in duodenal bile, with cholic acid accounting for 82.4% ± 5.5% of the total. Duodenal bile acid concentrations were 12.1 ± 5.9 mmol/L, which is too low for efficient lipid absorption. The biochemical profile was consistent with defective bile acid amidation. Molecular analysis of BAAT confirmed 4 different homozygous mutations in 8 patients tested. Conclusions: Based on a study of 10 pediatric patients, genetic defects that disrupt bile acid amidation cause fat-soluble vitamin deficiency and growth failure, indicating the importance of bile acid conjugation in lipid absorption. Some patients developed liver disease with features of a cholangiopathy. These findings indicate that patients with idiopathic neonatal cholestasis or later onset of unexplained fat-soluble vitamin deficiency should be screened for defects in bile acid conjugation.

Original languageEnglish (US)
Pages (from-to)945-955.e6
JournalGastroenterology
Volume144
Issue number5
DOIs
StatePublished - May 2013

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Keywords

  • Chronic Liver Disease
  • Hepatic
  • Inherited
  • Nutrient

ASJC Scopus subject areas

  • Hepatology
  • Gastroenterology

Cite this

Setchell, K. D. R., Heubi, J. E., Shah, S., Lavine, J. E., Suskind, D., Al-Edreesi, M., Potter, C., Russell, D. W., O'Connell, N. C., Wolfe, B., Jha, P., Zhang, W., Bove, K. E., Knisely, A. S., Hofmann, A. F., Rosenthal, P., & Bull, L. N. (2013). Genetic defects in bile acid conjugation cause fat-soluble vitamin deficiency. Gastroenterology, 144(5), 945-955.e6. https://doi.org/10.1053/j.gastro.2013.02.004