ORIGINAL ARTICLESIn-vitro and in-vivo effects of the CYP2C9*11 polymorphism on warfarin metabolism and doseTai, Guoyinga; Farin, Fredericob; Rieder, Mark J.c; Dreisbach, Albert W.d; Veenstra, David L.e; Verlinde, Christophe L.M.J.f; Rettie, Allan E.aAuthor Information Departments of aMedicinal Chemistry bEnvironmental Health Sciences cGenome Sciences fBiochemistry, University of Washington, Seattle, WA 98195, USA dDivision of Nephrology, Tulane University School of Medicine, New Orleans, LA 70112, USA eDepartment of Clinical Pharmacy, University of California, San Francisco, CA 94143, USA Sponsorship: This work was supported in part by NIH grants; GM068769 (A.E.R.), HL66682 (M.J.R.), RR05096 (A.W.D.) and NIEHS Center Grant P30-ES07033 (F.F. and C.L.M.J.V.). Correspondence and request for reprints to Allan E. Rettie PhD, Department of Medicinal Chemistry, Box 357610, University of Washington, Seattle, WA 98195, USA Tel: +1 206 685-0615; fax: +1 206 685-3252; e-mail: [email protected] Received 10 September 2004 Accepted 11 February 2005 Pharmacogenetics and Genomics: July 2005 - Volume 15 - Issue 7 - p 475-481 doi: 10.1097/01.fpc.0000162005.80857.98 Buy Metrics Abstract Objective To determine the in-vitro and in-vivo effects of the CYP2C9*11 polymorphism on (S)-warfarin metabolism. Methods and results The *11 allele that results in mutation of Arg335→Trp occurred with a frequency of ∼1% in Caucasian and African-American populations. Four subjects carrying the *1/*11 genotype were identified in a clinical cohort of 192 warfarin patients. Compared to control subjects with the *1/*11 genotype (n=127), the *1/*11 group exhibited a 33% reduction in warfarin maintenance dose, that was independent of study population age or INR. In-vitro studies directed towards understanding the mechanism of reduced in-vivo activity revealed very low levels of holo-CYP2C9.11 expression in insect cells and decreased solubility in the presence of detergent. Membrane preparations of CYP2C9.11 contained inactive P420 and exhibited a shorter half-life for thermally induced conversion of P450 to P420 than CYP2C9.1. Metabolic studies demonstrated that functional CYP2C9.11 possessed similar (S)-warfarin hydroxylation regioselectivity and modestly reduced catalytic efficiency relative to the wild-type enzyme. Conclusions In-vivo reduction in CYP2C9 (S)-warfarin activity due to the CYP2C9*11 polymorphism may largely be a consequence of decreased enzyme stability resulting in compromised expression of holo-enzyme. Increased enzyme lability of CYP2C9.11 may be related to improper folding due to the disruption of conserved salt-bridge and hydrogen bonding contacts in the loop region between the J and J′ helices of the protein. © 2005 Lippincott Williams & Wilkins, Inc.