Impaired hepatic drug and steroid metabolism in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency

Eur J Endocrinol. 2010 Dec;163(6):919-24. doi: 10.1530/EJE-10-0764. Epub 2010 Sep 15.

Abstract

Objective: Patients with congenital adrenal hyperplasia due to P450 oxidoreductase (POR) deficiency (ORD) present with disordered sex development and glucocorticoid deficiency. This is due to disruption of electron transfer from mutant POR to microsomal cytochrome P450 (CYP) enzymes that play a key role in glucocorticoid and sex steroid synthesis. POR also transfers electrons to all major drug-metabolizing CYP enzymes, including CYP3A4 that inactivates glucocorticoid and oestrogens. However, whether ORD results in impairment of in vivo drug metabolism has never been studied.

Design: We studied an adult patient with ORD due to homozygous POR A287P, the most frequent POR mutation in Caucasians, and her clinically unaffected, heterozygous mother. The patient had received standard dose oestrogen replacement from 17 until 37 years of age when it was stopped after she developed breast cancer.

Methods: Both subjects underwent in vivo cocktail phenotyping comprising the oral administration of caffeine, tolbutamide, omeprazole, dextromethorphan hydrobromide and midazolam to assess the five major drug-metabolizing CYP enzymes. We also performed genotyping for variant CYP alleles known to affect drug metabolism.

Results: Though CYP enzyme genotyping predicted normal or high enzymatic activities in both subjects, in vivo assessment showed subnormal activities of CYP1A2, CYP2C9, CYP2D6 and CYP3A4 in the patient and of CYP1A2 and CYP2C9 in her mother.

Conclusions: Our results provide in vivo evidence for an important role of POR in regulating drug metabolism and detoxification. In patients with ORD, in vivo assessment of drug-metabolizing activities with subsequent tailoring of drug therapy and steroid replacement should be considered.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Hyperplasia, Congenital / genetics*
  • Adrenal Hyperplasia, Congenital / metabolism
  • Adult
  • Aged
  • Antley-Bixler Syndrome Phenotype / genetics
  • Antley-Bixler Syndrome Phenotype / metabolism*
  • Aryl Hydrocarbon Hydroxylases / metabolism
  • Cytochrome P-450 CYP1A2 / metabolism
  • Cytochrome P-450 CYP2C9
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P-450 Enzyme System / metabolism
  • Disorders of Sex Development / genetics*
  • Female
  • Humans
  • Liver / metabolism*
  • Middle Aged
  • NADPH-Ferrihemoprotein Reductase / deficiency*
  • Steroids / metabolism*

Substances

  • Steroids
  • Cytochrome P-450 Enzyme System
  • CYP2C9 protein, human
  • Cytochrome P-450 CYP2C9
  • Aryl Hydrocarbon Hydroxylases
  • CYP1A2 protein, human
  • Cytochrome P-450 CYP1A2
  • NADPH-Ferrihemoprotein Reductase