Development and Cross-Validation of High-Resolution Melting Analysis-Based Cardiovascular Pharmacogenetics Genotyping Panel.

AIMS: This study was designed to develop a high-resolution melting (HRM) analysis-based cardiovascular (CV) pharmacogenetics (PGx) genotyping panel for the Canon DNA Genetic Analyzer multiplex genotyping platform and cross-validate its performance with the TaqMan®-based OpenArray® method. METHODS: The CV PGx genotyping panel containing 17 single nucleotide polymorphisms (SNPs) selected from 5 genes (CYP2C9, CYP2C19, CYP4F2, SLCO1B1, and VKORC1) and the CYP2C cluster was used to compare genotyping results between analysis methods. Genomic DNA from 223 clinical samples was used to genotype the 17 SNPs on the Canon DNA Genetic Analyzer and TaqMan OpenArray Quant Studio Real-Time PCR (polymerase chain reaction) System. RESULTS: The concordance between the Canon DNA analyzer and TaqMan-based OpenArray genotyping results for the 17 SNPs ranged from 99.10% to 100% where SNPs (rs4244285, rs12248560, rs4986893, rs72552267, rs28399504, rs4149056, rs28371686, rs9332131, rs72558189, rs9923231, rs12777823), (rs41291556, rs1799853, rs7900194, rs28371685, rs2108622), and (rs1057910) showed 100%, 99.60%, and 99.10% concordance, respectively. CONCLUSION: These results show that the HRM analysis-based CV PGx genotyping panel performed well when compared with TaqMan-based OpenArray. The multiple genetic variant testing capability, efficient turnaround time and reproducibility of both assays formats suggest that the PGx panel with the DNA analyzer or other real-time PCR instruments with HRM assay analysis capability can be used for PGx testing in both research and clinical practice settings.

Cross-Validation of High-Resolution Melting Analysis-Based Genotyping Platform.

AIMS: Developing genetic and pharmacogenetic panels enhances genetic testing in clinical molecular diagnostics and precision medicine. This study was designed to cross-validate the performance of Canon's multiplex high-resolution DNA melting analysis platform with the Applied Biosystems TaqMan®-based Quant Studio Real-Time PCR System and Pyrosequencing® genotyping platforms for common genetic polymorphisms of the vitamin K epoxide reductase complex 1 (VKORC1) and CYP2C9. MATERIALS AND METHODS: Genomic DNA isolated from 240 blood and saliva samples was used to genotype the VKORC1-1639 G/A (rs9923231), CYP2C9*2 (430C>T, rs28371674), and CYP2C9*3 (1075A>C, rs1057910) single-nucleotide polymorphisms (SNPs) on the three above-mentioned genotyping platforms. RESULTS: There was 99.2%, 100%, and 100% concordance among the Canon DNA analyzer, the TaqMan-based QuantStudio, and the Pyrosequencing genotyping results for the VKORC1 (rs9923231), CYP2C9*2, and CYP2C9*3 SNPs, respectively, in DNA samples isolated from blood. The DNA samples isolated from saliva showed 100% concordance among the three test platforms for the three tested SNPs. CONCLUSION: These results show that, the DNA analyzer performed very well when compared with two commonly used genotyping platforms. The reliability, multiple genetic variant testing capability, and short turnaround time for up to eight samples make the DNA analyzer an ideal genotyping platform for genetic testing in the clinical practice setting, where efficient genotyping is important to prevent delays in optimizing drug therapy.

Toxicological and Pharmacokinetic Evaluation of Concomitant Intake of Grapefruit Juice and Simvastatin in Rats after Repeated Treatment over 28 Days.

Since data concerning the toxicity and pharmacokinetics of concomitant repeated administration of grapefruit juice (GFJ) and simvastatin are lacking, we performed a chronic study in rats over a 4-week period using two different strengths (regular [RS] and double strength [DS]) of GFJ and two different doses of simvastatin (20 and 80 mg/kg, respectively). Both juices did not have a significant effect on the pharmacokinetic parameters of either simvastatin lactone (SVL) or its active metabolite simvastatin hydroxy acid (SVA) when administered concomitantly in a dose of 20 mg/kg over 28 days. However, when administered with 80 mg/kg simvastatin concentrations were elevated up to the last day of the study with DS-GFJ and to a lesser extent with RS-GFJ. Evaluation of toxicological parameters revealed a significant decrease in body and liver weights in groups receiving 20 mg/kg or 80 mg/kg simvastatin alone as well as in groups receiving simvastatin concomitantly with either DS- or RS-GFJ. No significant differences were detected for alanine (ALT) and aspartate (AST) aminotranferases in all groups. Chronic treatment with simvastatin significantly decreased plasma cholesterol levels (18 % for 20 mg/kg, 19 % for 80 mg/kg, respectively) as did coadministration of 80 mg/kg simvastatin with either RS-GFJ or DS-GFJ (33 %, 16 %). Interestingly, treatment with RS- or DS-GFJ alone significantly decreased plasma cholesterol levels by 22 % and 30 %, respectively. In conclusion, our results suggest that toxic effects in rats of concomitant intake of simvastatin and GFJ over 28 days are not more pronounced than those of simvastatin alone and that dose relationships between the administration of the juice and the drug may be important in determining the magnitude of the interaction.

Simultaneous determination of uric acid metabolites allantoin, 6-aminouracil, and triuret in human urine using liquid chromatography-mass spectrometry.

Uric acid (UA) can be directly converted to allantoin enzymatically by uricase in most mammals except humans or by reaction with superoxide. UA can react directly with nitric oxide to generate 6-aminouracil and with peroxynitrite to yield triuret; both of these metabolites have been identified in biological samples. We now report a validated high-performance liquid chromatography and tandem mass spectrometry method for the determination of these urinary UA metabolites. Urine samples were diluted 10-fold, filtered and directly injected onto HPLC for LC-MS/MS analysis. The urinary metabolites of UA were separated using gradient HPLC. Identification and quantification of UA urinary metabolites was performed with electrospray in positive ion mode by selected-reaction monitoring (SRM). Correlation coefficients were 0.991-0.999 from the calibration curve. The intra- and inter-day precision (R.S.D., %) of the metabolites ranged from 0.5% to 13.4% and 2.5-12.2%, respectively. In normal individuals (n=21), urinary allantoin, 6-aminouracil and triuret, were 15.30 (+/-8.96), 0.22 (+/-0.12), and 0.12 (+/-0.10) microg/mg of urinary creatinine (mean (+/-S.D.)), respectively. The new method was used to show that smoking, which can induce oxidative stress, is associated with elevated triuret levels in urine. Thus, the method may be helpful in identifying pathways of oxidative stress in biological samples.