Influence of ORM1 polymorphisms on the maintenance stable warfarin dosage

Effect of NPC1L1 polymorphism on warfarin stable dose in Chinese patients under heart valve replacement surgery

Warfarin is the most often anticoagulant choice for preventable thromboembolism. Notably, vitamin K plays a vital role in the process of warfarin's anticoagulant effect. Therefore, we presume NPC1L1, a key transporter of vitamin K (VK) intestinal absorption, may modulate the anticoagulant effect of warfarin. Studies have shown that NPC1L1(-762T>C, rs2073548) and p53 (P72R, rs1042522) variations are implicated in influencing NPC1L1 expression. This study aimed to assess the association between these two variants and warfarin stable dose (WSD). A two-stage extreme phenotype design was used to explore the influence of these two variants (rs2073548, rs1042522) on WSD variance in 655 Chinese patients undergoing heart valve replacement surgery. NPC1L1 rs2073548, p53 rs1042522, VKORC1 rs9923231 and CYP2C9*1/*3 polymorphisms were genotyped by polymerase chain reaction-restriction fragment polymorphism (PCR-RFLP) or Sanger sequencing, respectively. WSD was identified when target monitoring international normalized ratio (INR) value at 2.0-3.0. In the discovery phase, NPC1L1 rs2073548 A allele carriers occupied a significantly higher rate in the low dose group (P = .019). However, in the validation group, warfarin dosage in patients with the rs2073548 AA, AG and GG genotypes were 2.91 ± 0.97 mg/day, 3.02 ± 1.00 mg/day and 3.00 ± 1.06 mg/day, respectively. Multiple linear regression analysis results suggested that CYP2C9*3 and VKORC1 rs9923231, but not NPC1L1 rs2073548, were independent predictors of WSD in Chinese heart valve replacement (HVR) surgical patients.

Effect of gene polymorphism on bleeding complications in Chinese Han patients taking warfarin

PURPOSE

The purpose of this study was to analyse the effects of demographic factors, clinical factors, and genetic polymorphisms of related gene loci on warfarin bleeding-related complications in the Han population.

METHODS

Retrospective medical record review. The study cases were patients treated at the Fujian Medical University Union Hospital from March 2016 to February 2020, and all received regular warfarin anticoagulation treatment for at least 3 months, and were provided the initial standard dose and stable dose of warfarin.

RESULTS

Data were collected from 451 qualifying patients (47% male, 53% female). The average age of patients was 53.8 ± 12.2 years, and the average body surface area was 1.6 ± 0.18 m². There were nine major bleeding events and 141 minor bleeding events. In the univariate logistic analysis, the p-value of the four factors body weight, body surface area (BSA), amiodarone, and rs429358 was < 0.10. However, the final p-values for amiodarone and rs429358 were < 0.05 in the multifactorial logistic analysis.

CONCLUSIONS

The ApoE (rs429358) gene polymorphism influences bleeding complications in Chinese Han patients treated with warfarin. The sample size of this study was relatively small; hence an international study with a larger sample size is needed in the future.

The pharmacoepigenomics informatics pipeline defines a pathway of novel and known warfarin pharmacogenomics variants

AIM

'Pharmacoepigenomics' methods informed by omics datasets and pre-existing knowledge have yielded discoveries in neuropsychiatric pharmacogenomics. Now we evaluate the generality of these methods by discovering an extended warfarin pharmacogenomics pathway.

MATERIALS & METHODS

We developed the pharmacoepigenomics informatics pipeline, a scalable multi-omics variant screening pipeline for pharmacogenomics, and conducted an experiment in the genomics of warfarin.

RESULTS

We discovered known and novel pharmacogenomics variants and genes, both coding and regulatory, for warfarin response, including adverse events. Such genes and variants cluster in a warfarin response pathway consolidating known and novel warfarin response variants and genes.

CONCLUSION

These results can inform a new warfarin test. The pharmacoepigenomics informatics pipeline may be able to discover new pharmacogenomics markers in other drug-disease systems.

The Impact of Gene Polymorphisms on Anticoagulation Control With Warfarin

Differences in warfarin maintenance dosages based on the presence of polymorphisms in VKORC1, CYP2C9, CYP4F2, and ORM1 can be determined through dosage adjustment according to routine guidelines. Little is known about whether routine therapy could provide consensus anticoagulation control for patients with different genotypes. This study was carried out to compare anticoagulant control in patients with different genotypes. Six hundred seventy patients using warfarin according to Chinese guidelines were enrolled. Warfarin dosages and monitored international normalized ratios (INRs) were recorded. Genotypes of VKORC1 rs9923231, CYP4F2 rs2108622, CYP2C9 rs1057910, and ORM1 rs17650 polymorphisms were determined. Warfarin dosages and INR were compared between genotypes. Patients with the AGCC*F*F*1*1 polymorphism took longer than patients with the AACC*F*F*1*1 polymorphism (20 vs 5 days, P < .001) to achieve the targeted INR range. The INR values of patients with AACC*F*F*1*3 were unstable and did not enter the stable state control phase until after 35 days. The peak INR of patients with the AACC*F*F*1*3 polymorphism was exceedingly high, with some values exceeding the control range limit of 3.0. Patients with the AACC*F*S*1*1 or AACT*F*F*1*1 polymorphisms exhibited similar INR values as the patients with the AACC*F*F*1*1 polymorphism. This study found that routine medication with warfarin provides significantly different levels of anticoagulant control between patients with wild-type genotypes and patients with heterozygous polymorphism genotypes of VKORC1 rs9923231 or CYP2C9 rs1057910. Patients with heterozygous polymorphism genotypes of VKORC1 or CYP2C9 require genotype-directed therapy with warfarin to increase efficacy and safety in anticoagulant treatment.

Identification of novel variants associated with warfarin stable dosage by use of a two-stage extreme phenotype strategy

Essentials Required warfarin doses for mechanical heart valves vary greatly. A two-stage extreme phenotype design was used to identify novel warfarin dose associated mutation. We identified a group of variants significantly associated with extreme warfarin dose. Four novel identified mutations account for 2.2% of warfarin dose discrepancies.

SUMMARY

Background The variation among patients in warfarin response complicates the management of warfarin therapy, and an improper therapeutic dose usually results in serious adverse events. Objective To use a two-stage extreme phenotype strategy in order to discover novel warfarin dose-associated mutations in heart valve replacement patients. Patients/method A total of 1617 stable-dose patients were enrolled and divided randomly into two cohorts. Stage I patients were genotyped into three groups on the basis of VKORC1-1639G>A and CYP2C9*3 polymorphisms; only patients with the therapeutic dose at the upper or lower 5% of each genotype group were selected as extreme-dose patients for resequencing of the targeted regions. Evaluation of the accuracy of the sequence data and the potential value of the stage I-identified significant mutations were conducted in a validation cohort of 420 subjects. Results A group of mutations were found to be significantly associated with the extreme warfarin dose. The validation work finally identified four novel mutations, i.e. DNMT3A rs2304429 (24.74%), CYP1A1 rs3826041 (47.35%), STX1B rs72800847 (7.01%), and NQO1 rs10517 (36.11%), which independently and significantly contributed to the overall variability in the warfarin dose. After addition of these four mutations, the estimated regression equation was able to account for 56.2% (R2Adj = 0.562) of the overall variability in the warfarin maintenance dose, with a predictive accuracy of 62.4%. Conclusion Our study provides evidence linking genetic variations in STX1B, DNMT3A and CYP1A1 to warfarin maintenance dose. The newly identified mutations together account for 2.2% of warfarin dose discrepancy.

Frequency of Common VKORC1 Polymorphisms and Their Impact on Warfarin Dose Requirement in Pakistani Population

Polymorphisms in vitamin K epoxide reductase complex subunit 1 (VKORC1) gene lead to interindividual variability in warfarin dose requirement. The characterization of genotype frequency distribution is required in different populations for construction of customized dosing algorithms to enhance the efficacy and reduce the toxicity of warfarin therapy. This study was carried out in Pakistani population to evaluate the contribution of common VKORC1 polymorphisms to warfarin therapy. A total of 550 stable patients taking warfarin were enrolled after medical history, physical examination, and laboratory investigations. Single blood sample was collected after informed consent. Genomic DNA was extracted and genotype analysis for VKORC1 1173C>T and VKORC1-1639G>A polymorphisms was done by polymerase chain reaction-restriction fragment length polymorphism assay. A number of samples were also analyzed by direct DNA sequencing for validation of results. Data were analyzed using SPSS version 20. Genotype frequency distributions of VKORC1 1173C>T and VKORC1-1639G>A were found to be different from other populations. Both of these polymorphisms did not demonstrate significant effect on warfarin dose requirement. Although Cytochrome P450 2C9 (CYP2C9) and VKORC1 polymorphisms together attributed only 3.8% variability in warfarin dose but it was statistically significant ( p value = .004). It is concluded that there is a need to study genotype frequency distribution and their effect on warfarin dose variability among different populations due to diversity in outcome. At the same time, no effect on warfarin dose variation explained by VKORC1 polymorphisms and small variability explained by studied genotypes stresses the need for exploration of more genetic and nongenetic factors in Pakistani population.

Frequency of Common CYP2C9 Polymorphisms and Their Impact on Warfarin Dose Requirement in Pakistani Population

Polymorphisms in cytochrome P450 (CYP) 2C9 (CYP2C9) gene result in interindividual variability in warfarin dose requirement. There is a need for characterization of genotype frequency distribution in different populations for construction of customized dosing algorithms to enhance the efficacy and reduce the toxicity of warfarin therapy. This study was carried out in Pakistani population to evaluate the contribution of common CYP2C9 polymorphisms to warfarin therapy. A total of 550 stable patients taking warfarin were enrolled after medical history, physical examination, and laboratory investigations. Single blood sample was collected after informed consent. Genomic DNA was extracted, and genotype analysis for CYP2C9*2 and CYP2C9*3 polymorphisms was done by polymerase chain reaction-restriction fragment length polymorphism assay. A number of samples were also analyzed by direct DNA sequencing for validation of the results. Data were analyzed using SPSS version 20. Genotype frequency distribution of CYP2C9*2 and CYP2C9*3 was found to be different from other populations. Of these 2 polymorphisms, CYP2C9*2 did not demonstrate significant effect on warfarin dose requirement, whereas CYP2C9*3 did show significant effect ( P value = .012). It is concluded that there is a need to study genotype frequency distribution and their effect on warfarin dose variability among different populations due to diversity in outcome.

Functional Study of Haplotypes in UGT1A1 Promoter to Find a Novel Genetic Variant Leading to Reduced Gene Expression

BACKGROUND

Uridine diphosphate glucuronyltransferase 1 family, A1 (UGT1A1) encodes for an enzyme that is a part of glucuronidation pathway, and a number of studies have shown that the promoter polymorphisms of UGT1A1 are associated with various diseases and drug response. In this study, we examined a possible association between UGT1A1 promoter haplotypes and the gene expression level.

METHODS

To identify promoter haplotype structure population, we directly sequenced the promoter region of UGT1A1 in 192 healthy Korean to identify 10 UGT1A1 promoter single-nucleotide polymorphisms (SNPs). Then, we genotyped the 10 SNPs in additional 192 non-Korean samples comprised of Chinese, Japanese, European American, and African American, and constructed haplotype structures. Furthermore, we conducted luciferase assay for the promoter SNP haplotypes to examine a possible expression change.

RESULTS

rs3755319C-rs2003569A-rs887829C-rs8175347(TA)6 (6.60 ± 0.15) and rs3755319A-rs2003569 G-rs887829C-rs8175347(TA)7 (2.79 ± 0.97) led to significantly lower gene expression when compared with rs3755319C-rs2003569 G-rs887829T-rs8175347(TA)6 (8.28 ± 0.60).

CONCLUSIONS

Our result suggests that the haplotypes in UGT1A1 promoter region can affect the expression level of the gene and drug metabolism associated with UGT1A1. Furthermore, in addition to rs8175347, rs3755319 was found to induce lower gene expression of UGT1A1.

Effect of gene polymorphims on the warfarin treatment at initial stage

The adverse reactions of warfarin that were found mainly occurred in the first month. This study was carried out to observe the effect of gene polymorphisms on the warfarin therapy at the initial stage. Four-hundred and sixty Chinese patients began warfarin treatment with daily 2.5 mg after heart valve replacement operations were enrolled. The daily international normalized ratio (INR) for anticoagulation were recorded till the seventh day. Blood samples were collected and used to detect genotypes for VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650. INR and their changes were compared among genotypes. INR was partially correlated with the VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650 polymorphisms from the third, fourth and sixth day on, respectively. VKORC1 rs7294 and CYP4F2 rs2108622 carriers responded lower than the wild genotype, whereas CYP2C9 rs1057910 and ORM1 rs17650 carriers responded higher, respectively. Fifty percent of AA/*1*3/CC/*S*S patients and 16% of AA/*1*1/CC/*S*S patients were over anticoagulation treated with INR >4.0 at the third day. Ninety percent of VKORC1 rs7294 carrier patients have INR <1.63, a mark of the 25% of lower responders of the wild genotype. Our study provided another kind of evidence that VKORC1 rs7294, CYP2C9 rs1057910, CYP4F2 rs2108622 and ORM1 rs17650 affected the action of warfarin in different styles. Patients with AA/*1*1/CC/*S*S, AA/*1*3/CC/*S*S should use a less initial dosage to avoid over anticoagulation, and patients with VKORC1 rs7294 should use larger initial dose to proof an effective therapy.

First report of warfarin dose requirements in patients possessing the CYP2C9*12 allele

BACKGROUND

Warfarin is the most frequently prescribed anticoagulant in North America and Europe. It is administered as a racemate, but S-warfarin is principally responsible for its anticoagulant activity. Cytochrome P450 (CYP) 2C9 is the enzyme primarily responsible for the metabolism of S-warfarin. Numerous variant alleles of CYP2C9 have been identified. The CYP2C9*12 (rs9332239) allele harbors a P489S substitution in CYP2C9 which has been shown to result in a 40% decline in catalytic activity in vitro.

CASES

Four Caucasian patients with a low mean weekly warfarin dose (MWWD) were genotyped for CYP2C9, VKORC1 and APOE variant alleles. None of the four patients carried the common CYP2C9 variant alleles (*2, *3, *5, *6, *7, *8, *9, *11, *13) despite a relatively low MWWD (23.4±7.94 mg) compared to 208 patients carrying the CYP29C9*1 genotype (32.2±12.65 mg). Given that CYP2C9*12 confers decreased in vitro activity to the enzyme, we investigated whether these patients carried this allele. All four patients were CYP2C9*12 CT heterozygotes. Individual comparisons with patients possessing the same VKORC1 and APOE genotypes also demonstrated lower dose requirements in the patients that possessed CYP2C9*12 allele.

CONCLUSIONS

There are no reports of the clinical impact of rs9332239 on CYP2C9 substrates. This is the first report of patients with the rare CYP2C9*12 genotype and lower warfarin dose requirements.