Evaluation of the Effects of 20 Nonsynonymous Single Nucleotide Polymorphisms of CYP2C19 onS-Mephenytoin 4′-Hydroxylation and Omeprazole 5′-Hydroxylation

Abstract

ABSTRACT:CYP2C19 is a highly polymorphic enzyme that affects the metabolism of a wide range of therapeutic drugs. Almost all the identified alleles of CYP2C19 are derived from nonsynonymous single nucleotide polymorphisms (nsSNPs). The objective of this study was to functionally characterize 20 nsSNPs of CYP2C19, distributed throughout the entire coding region, most of which have not been thoroughly characterized. cDNAs of these variants were constructed and expressed in yeast cells. All variants had similar levels of apoprotein and holoprotein expression, except for CYP2C19.16 and D360N, which had significantly lower holoprotein levels than the wild-type (WT) CYP2C19 enzyme, and CYP2C19.5B, which showed only apoprotein. The activity of the CYP2C19 variants was investigated using two substrates, S-mephenytoin and omeprazole, and six different kinetic parameters were measured. CYP2C19.5B, CYP2C19.6, and CYP2C19.8 were found to be catalytically inactive. The entire dataset of the remaining 17 variants, together with the WT, was analyzed by multivariate analysis. This analysis indicated that CYP2C19.9, CYP2C19.10, CYP2C19.16, CYP2C19.18, CYP2C19.19, A161P, W212C, and D360N were substantially altered in catalytic properties in comparison with the WT, with each of these variants exhibiting either dramatically decreased catalytic activities or higher K m values. These results not only generally confirmed the function of previously reported variants but also identified additional reduced-function variants. These findings will greatly extend our understanding of CYP2C19 genetic polymorphisms in humans as well as facilitate the structure-function study of the CYP2C19 protein.

Association of CYP2C19*2 and associated haplotypes with lower norendoxifen concentrations in tamoxifen‐treated Asian breast cancer patients

“…Prior to investigating the impact of CYP2C19 genetic variations on tamoxifen metabolism, a comprehensive genetic screening of CYP2C19 was conducted to explore the genetic diversity of CYP2C19 in healthy Asian populations, which revealed the highly polymorphic nature of CYP2C19 . Thus far, 41 polymorphisms have been reported in the coding regions of CYP2C19 albeit with variable functional consequences . The majority of these variants are ethnic specific and were not observed in this study with the exception of 99C > T (rs17885098), 518C > T (rs61311738), 636G > A (* 3 ; rs4986893), 681G > A (* 2 ; rs4244285), 990C > T (rs3758580), 991 A > G (rs3758581) and 1251 A > C (rs17886522).…”

Cytochrome P450 Gene Variants, Race, and Mortality Among Clopidogrel-Treated Patients After Acute Myocardial Infarction

“…Given that the two CYP2C19 *17 variants were in tight LD in our cohort (Supplemental Figure S1), consistent with others’ data, 35 we restricted our analyses to the functional, ‘defining’ CYP2C19 *17 variant ( CYP2C19 *17 -806; rs12248560) that is responsible for a C>T transition in the CYP2C19 promoter that creates a new consensus binding site for the GATA transcription factor family, resulting in increased CYP2C19 expression and activity. 36 …”

Prediction of In Vivo Clearance and Associated Variability of CYP2C19 Substrates by Genotypes in Populations Utilizing a Pharmacogenetics-Based Mechanistic Model

“…Lastly, the present prediction framework is applicable to modeling genetic impact of 2C19*2-*8 and *17 that only alter protein expression (Solus et al, 2004). For CYP2C19 variants with altered substrate affinity in addition to protein expression (Wang et al, 2011b), in vitro metabolic data from HLMs carrying such variants should be collected as in the present study and then incorporated into the prediction framework as demonstrated in the CYP2B6 PGx-based modeling (Xu et al, 2013).…”