The field of Pharmacogenomics seeks to delineate the genetic factors responsible for variations in drug response, both among individuals in one ethnic group and between population groups. To date, most effort in pharmacogenomics has focused on polymorphic variants in drug-metabolizing hepatic cytochrome P450 (CYP) enzymes. This proposal will address a previously unexplored potential basis for variation in drug metabolism, NADPH-dependent P450 oxidoreductase (POR). For microsomal cytochrome P450's POR is the only source of the electrons necessary to achieve catalysis. POR accepts electrons from NADPH and transfers them to the P450. Although the phenotype of POR knockout mice is an embryonic lethal, surprisingly we recently found that human POR missense mutations are responsible for a broad spectrum of human disease, ranging from a normal female phenotype with amenorrhea, to severely malformed infants with the Antley-Bixler syndrome (ABS). Other data suggest that POR mutations disrupt fetal drug metabolism, apparently rendering an otherwise benign drug (fluconazole) teratogenic. The frequency, severity and ethnic distribution of POR missense mutations, either those severe enough to cause disease or those that may be phenotypically silent, is unknown. To assess the potential role of POR sequence variants in variations in drug response, we propose the following four Specific Aims:
Aim 1. Identify and characterize the spectrum of POR mutations causing identifiable human disease.
Aim 2. Delineate the spectrum of POR sequence variants and polymorphisms in the normal human population.
Aim 3. Assess the impact of POR missense mutants or variants on the eight most important hepatic P450 enzymes (CYP1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4).
Aim 4. Determine whether sequence variants of POR and CYP enzymes that have minimal loss of activity individually can, in combination, lead to significant diminution in the activity of these enzymes. Successful completion of these aims will substantially increase knowledge about the genetic factors leading to variations in drug response.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Xenobiotic and Nutrient Disposition and Action Study Section (XNDA)
Program Officer
Okita, Richard T
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California San Francisco
Schools of Medicine
San Francisco
United States
Zip Code
Jin, Yi; Chen, Mo; Penning, Trevor M et al. (2015) Electron transfer by human wild-type and A287P mutant P450 oxidoreductase assessed by transient kinetics: functional basis of P450 oxidoreductase deficiency. Biochem J 468:25-31
Tee, Meng Kian; Miller, Walter L (2013) Phosphorylation of human cytochrome P450c17 by p38? selectively increases 17,20 lyase activity and androgen biosynthesis. J Biol Chem 288:23903-13
Subramanian, Murali; Agrawal, Vishal; Sandee, Duanpen et al. (2012) Effect of P450 oxidoreductase variants on the metabolism of model substrates mediated by CYP2C9.1, CYP2C9.2, and CYP2C9.3. Pharmacogenet Genomics 22:590-7
Miller, Walter L (2012) P450 oxidoreductase deficiency: a disorder of steroidogenesis with multiple clinical manifestations. Sci Signal 5:pt11
Tee, Meng Kian; Huang, Ningwu; Damm, Izabella et al. (2011) Transcriptional regulation of the human P450 oxidoreductase gene: hormonal regulation and influence of promoter polymorphisms. Mol Endocrinol 25:715-31
Sandee, Duanpen; Miller, Walter L (2011) High-yield expression of a catalytically active membrane-bound protein: human P450 oxidoreductase. Endocrinology 152:2904-8
Miller, Walter L; Agrawal, Vishal; Sandee, Duanpen et al. (2011) Consequences of POR mutations and polymorphisms. Mol Cell Endocrinol 336:174-9
Agrawal, Vishal; Choi, Ji Ha; Giacomini, Kathleen M et al. (2010) Substrate-specific modulation of CYP3A4 activity by genetic variants of cytochrome P450 oxidoreductase. Pharmacogenet Genomics 20:611-8
Sandee, Duanpen; Morrissey, Kari; Agrawal, Vishal et al. (2010) Effects of genetic variants of human P450 oxidoreductase on catalysis by CYP2D6 in vitro. Pharmacogenet Genomics 20:677-86
Miller, Walter L (2009) Androgen synthesis in adrenarche. Rev Endocr Metab Disord 10:3-17

Showing the most recent 10 out of 23 publications