Pharmacogenetic distribution of warfarin and its clinical significance in Korean patients during initial anticoagulation therapy.

During warfarin treatment, determining the optimal dose and maintaining the target PT-INR are challenging. Increasing evidence supports the theory that genotypic polymorphisms influence an individual's warfarin dose requirement. In this study, we evaluated allele frequencies and effects of CYP2C9 and VKORC1 on warfarin response during initial anticoagulation therapy in Korean patients. We enrolled patients who had initiated warfarin therapy and undergone PT-INR testing at least three times within the first month of anticoagulation therapy. All the participating patients were tested for the detection of CYP2C9*3 (c.1075A>C) and VKORC1-1639G>A. A melting-curve analysis after real-time PCR was performed using CYP2C9*3 and VK1639 genotyping kits (Idaho Technology, US). A total of 37 patients were enrolled in this study. CYP2C9*1/*1 (87%) and VKORC1-1639AA genotypes (89%) were predominant in Korea. The CYP2C9*3 and VKORC1-1639G alleles were found in five (13%) and four patients (11%), respectively. Patients with the CYP2C9*3 allele received a lower warfarin dose (P = 0.018) and tended to show more rapid PT-INR increase than CYP2C9*1/*1 genotype. Patients with the VKORC1-1639G allele nonsignificantly received higher warfarin dose than those without. The CYP2C9*3 and VKORC1-1639G alleles influenced warfarin response during the first month of anticoagulation therapy. Considering these results, CYP2C9 and VKORC1 genotyping can be an useful tool to estimate initial warfarin dose and frequency of PT-INR monitoring during the first month of anticoagulation therapy.

Time Points for Gonadotropin-Releasing Hormone Stimulation Test Results in Korean Children.

The gold standard for the laboratory diagnosis of central precocious puberty is based on the measurement of luteinizing hormone (LH) after gonadotropin-releasing hormone (GnRH) stimulation. We sought to investigate the laboratory data for GnRH stimulation testing using samples collected from Korean children at different time points. Sampling times were at the basal time point (0) and 15, 30, 45, 60, 90, and 120 min after GnRH stimulation. Pubertal response was defined as occurring when the peak LH concentration was 5 IU/L or more and rose to at least 2 times the basal LH concentration after GnRH stimulation. During the study period, 19,990 test results from 1958 Korean children (1841 females aged 1.3-8.9 years and 117 males aged 7.3-9.9 years) were obtained. Among the 1958 children, 1232 (62.9%) showed pubertal responses. The receiver operating characteristic curve that demonstrated the greatest area under the curve (AUC) among all examined time points was 45 min after GnRH stimulation in males (AUC 0.982, 95% CI 0.938-0.998) and 60 min in females (AUC 0.975, 95% CI 0.967-0.981). The combination of 45 min and 60 min showed the greatest AUC (0.996, 95% confidence interval 0.991-0.998), with a sensitivity level of 99.1% and a specificity of 100% for all children. The results of this study provide a possibility for a reduction in sampling time points (45 min and 60 min) to identify the presence of a pubertal response after GnRH stimulation in Korean children.

Evaluation of three automated nucleic acid extraction systems for identification of respiratory viruses in clinical specimens by multiplex real-time PCR.

A total of 84 nasopharyngeal swab specimens were collected from 84 patients. Viral nucleic acid was extracted by three automated extraction systems: QIAcube (Qiagen, Germany), EZ1 Advanced XL (Qiagen), and MICROLAB Nimbus IVD (Hamilton, USA). Fourteen RNA viruses and two DNA viruses were detected using the Anyplex II RV16 Detection kit (Seegene, Republic of Korea). The EZ1 Advanced XL system demonstrated the best analytical sensitivity for all the three viral strains. The nucleic acids extracted by EZ1 Advanced XL showed higher positive rates for virus detection than the others. Meanwhile, the MICROLAB Nimbus IVD system was comprised of fully automated steps from nucleic extraction to PCR setup function that could reduce human errors. For the nucleic acids recovered from nasopharyngeal swab specimens, the QIAcube system showed the fewest false negative results and the best concordance rate, and it may be more suitable for detecting various viruses including RNA and DNA virus strains. Each system showed different sensitivity and specificity for detection of certain viral pathogens and demonstrated different characteristics such as turnaround time and sample capacity. Therefore, these factors should be considered when new nucleic acid extraction systems are introduced to the laboratory.

Genetic polymorphisms and plasma levels of tissue factor and tissue factor pathway inhibitor in venous thromboembolism.

Tissue factor (TF) and tissue factor pathway inhibitor (TFPI) play important roles in coagulation. The aim of this study was to investigate the distributions of TF and TFPI polymorphisms in Koreans and to analyze the association of these genetic polymorphisms with plasma levels and development of venous thromboembolism (VTE). The polymorphisms TF 5466 A > G, TF -603 A > G, TFPI -287 T > C and TFPI -33 T > C were investigated in 40 Korean VTE patients and 40 age-matched and sex-matched controls by real-time PCR followed by melting curve analysis and DNA sequence analysis. Plasma levels of TF and TFPI were measured by enzyme-linked immunosorbent assay. The G allele of TF 5466 was not detected, and allelic frequencies of TF -603 G, TFPI -287 C and TFPI -33 C were 27.5, 67.5 and 16.2%, respectively. The distributions of TF and TFPI polymorphisms were not different between patients and controls. The presence of TF -603 G allele was correlated with low plasma TF levels (P = 0.029). Mean plasma TFPI levels were similar between TFPI genotypic groups. Although not statistically significant, plasma TF and TFPI levels were higher in patients than controls. The distributions of TF and TFPI polymorphisms in Koreans were considerably different from whites, suggesting ethnic variations. The TF -603 A > G polymorphism was significantly correlated with decreased plasma TF levels. Neither genetic polymorphisms in TF and TFPI nor their plasma levels seem to act as direct risk factors for VTE.