Genetic Characterization of Molecular Targets in Korean Patients with Gastrointestinal Stromal Tumors

PURPOSE: Gastrointestinal stromal tumors (GISTs) frequently harbor activating gene mutations in either KIT or platelet-derived growth factor receptor A (PDGFRA) and are highly responsive to several selective tyrosine kinase inhibitors. In this study, a targeted next-generation sequencing (NGS) assay with an Oncomine Focus Assay (OFA) panel was used for the genetic characterization of molecular targets in 30 Korean patients with GIST.MATERIALS AND METHODS: Using the OFA that enables rapid and simultaneous detection of hotspots, single nucleotide variants (SNVs), insertion and deletions (Indels), copy number variants (CNVs), and gene fusions across 52 genes relevant to solid tumors, targeted NGS was performed using genomic DNA extracted from formalin-fixed and paraffin-embedded samples of 30 GISTs.RESULTS: Forty-three hotspot/other likely pathogenic variants (33 SNVs, 8 Indels, and 2 amplifications) in 16 genes were identified in 26 of the 30 GISTs. KIT variants were most frequent (44%, 19/43), followed by 6 variants in PIK3CA, 3 in PDGFRA, 2 each in JAK1 and EGFR, and 1 each in AKT1, ALK, CCND1, CTNNB1, FGFR3, FGFR4, GNA11, GNAQ, JAK3, MET, and SMO. Based on the mutation types, majority of the variants carried missense mutations (60%, 26/43), followed by 8 frameshifts, 6 nonsense, 1 stop-loss, and 2 amplifications.CONCLUSIONS: Our study confirmed the advantage of using targeted NGS with a cancer gene panel to efficiently identify mutations associated with GISTs. These findings may provide a molecular genetic basis for developing new drugs targeting these gene mutations for GIST therapy.

Circulating Respiratory Syncytial Virus Genotypes and Genetic Variability of the G Gene during 2017 and 2018/2019 Seasonal Epidemics Isolated from Children with Lower Respiratory Tract Infections in Daejeon, Korea

Background@#Respiratory syncytial virus (RSV) is a major pathogen causing respiratory tract infections in infants and young children. The aim of this study was to confirm the genetic evolution of RSV causing respiratory infections in children at Daejeon in Korea, through G gene analysis of RSV-A and RSV-B strains that were prevalent from 2017 to 2019. @*Methods@#Pediatric patients admitted for lower respiratory tract infections at The Catholic University of Korea Daejeon St. Mary's Hospital in the 2017 and 2018/2019 RSV seasonal epidemics, who had RSV detected via multiplex polymerase chain reaction (PCR) were included. The nucleic acid containing RSV-RNA isolated from each of the patients' nasal discharge during standard multiplex PCR testing was stored. The G gene was sequenced and phylogenetic analysis was performed using MEGA X program and the genotype was confirmed. @*Results@#A total of 155 specimens including 49 specimens from 2017 and 106 specimens from 2018-2019 were tested. The genotype was confirmed in 18 specimens (RSV-A:RSV-B = 4:14) from 2017 and 8 specimens (RSV-A:RSV-B = 7:1) from 2018/2019. In the phylogenetic analysis, all RSV-A type showed ON1 genotype and RSV-B showed BA9 genotype. @*Conclusion@#RSV-B belonging to BA9 in 2017, and RSV-A belonging to ON1 genotype in 2018/2019 was the most prevalent circulating genotypes during the two RSV seasons in Daejeon, Korea.

Circulating Respiratory Syncytial Virus Genotypes and Genetic Variability of the G Gene during 2017 and 2018/2019 Seasonal Epidemics Isolated from Children with Lower Respiratory Tract Infections in Daejeon, Korea

Background@#Respiratory syncytial virus (RSV) is a major pathogen causing respiratory tract infections in infants and young children. The aim of this study was to confirm the genetic evolution of RSV causing respiratory infections in children at Daejeon in Korea, through G gene analysis of RSV-A and RSV-B strains that were prevalent from 2017 to 2019. @*Methods@#Pediatric patients admitted for lower respiratory tract infections at The Catholic University of Korea Daejeon St. Mary's Hospital in the 2017 and 2018/2019 RSV seasonal epidemics, who had RSV detected via multiplex polymerase chain reaction (PCR) were included. The nucleic acid containing RSV-RNA isolated from each of the patients' nasal discharge during standard multiplex PCR testing was stored. The G gene was sequenced and phylogenetic analysis was performed using MEGA X program and the genotype was confirmed. @*Results@#A total of 155 specimens including 49 specimens from 2017 and 106 specimens from 2018-2019 were tested. The genotype was confirmed in 18 specimens (RSV-A:RSV-B = 4:14) from 2017 and 8 specimens (RSV-A:RSV-B = 7:1) from 2018/2019. In the phylogenetic analysis, all RSV-A type showed ON1 genotype and RSV-B showed BA9 genotype. @*Conclusion@#RSV-B belonging to BA9 in 2017, and RSV-A belonging to ON1 genotype in 2018/2019 was the most prevalent circulating genotypes during the two RSV seasons in Daejeon, Korea.

Performance Evaluation of the Beckman Coulter DxN VERIS Hepatitis B Virus (HBV) Assay in Comparison With the Abbott RealTime HBV Assay

The detection and quantification of hepatitis B virus (HBV) DNA plays an important role in diagnosing and monitoring HBV infection as well as in assessing the therapeutic response. We compared the analytical performance of a random access, fully automated HBV assay—DxN VERIS Molecular Diagnostics System (Beckman Coulter, Brea, CA, USA)—with that of Abbott RealTime HBV assay (Abbott Laboratories, Des Plaines, IL, USA). The between-day precision of the VERIS assay ranged from 0.92% (mean 4.68 log IU/mL) to 4.15% (mean 2.09 log IU/mL) for pooled sera from HBV patients. HBV DNA levels measured by the VERIS HBV assay correlated with the calculated HBV DNA levels (r²=0.9994; P < 0.0001). The lower limit of quantification was estimated as 8.76 IU/mL (Probit analysis, 95% confidence interval: 7.32–12.00 IU/mL). Passing-Bablok regression analysis showed good concordance between the VERIS and RealTime assays for 187 chronic HBV samples (y=−0.2397+0.9712x; r=0.981), as well as for 20 drug-resistant HBV genotype C positive samples (y=−0.5415+0.9954x; r=0.961). The VERIS assay demonstrated performance similar to the RealTime assay and is suitable for high-throughput HBV DNA monitoring in large hospital laboratories.

Prescription of Antibiotics for Adults with Acute Infectious Diarrhea in Korea: A Population-based Study

BACKGROUND@#Acute infectious diarrhea (AID) is a commonly observed condition globally. Several studies recommend against the use of empiric antibiotic therapy for AID, except in some cases of travelers' diarrhea. However, many physicians prescribe antimicrobial agents for AID. We aimed to determine the rate of antibiotic use and the associated prescription patterns among adults with AID.@*MATERIALS AND METHODS@#This population-based, retrospective epidemiological study was performed using Korean National Health Insurance claims data from 2016 to 2017. The study population comprised adults (age ≥18 years) who had visited clinics with AID-related complaints. Exclusion criteria were the presence of Crohn's disease, ulcerative colitis, irritable bowel syndrome, and other non-infectious forms of colitis. Patients who underwent surgery during admission were also excluded.@*RESULTS@#The study population comprised 1,613,057 adult patients with AID (767,606 [47.6%] men). Young patients (age 18 – 39 years) accounted for 870,239 (54.0%) of the study population. Overall, 752,536 (46.7%) cases received antibiotic prescriptions. The rate of antibiotic administration tended to be higher among elderly patients (age ≥65 years) than among younger patients (49.5% vs. 46.4%, P <0.001). The antibiotics most frequently prescribed in both monotherapy and combination regimens were fluoroquinolones (29.8%), rifaximin (26.8%), second-generation cephalosporins (9.2%), third-generation cephalosporins (7.3%), trimethoprim/sulfamethoxazole (5.5%), and β-lactam/β-lactamase inhibitors (5.3%). Patients who visited tertiary care hospitals had lower rates of antibiotic therapy (n = 14,131, 41.8%) than did those visiting private clinics (n = 532,951, 47.1%). In total, 56,275 (62.3%) admitted patients received antibiotic therapy, whereas outpatients had lower rates of antibiotic prescription (n = 694,204, 46.0%).@*CONCLUSION@#This study revealed differences between the antibiotics used to treat AID in Korea and those recommended by the guidelines for AID treatment. Multifaceted efforts are necessary to strengthen physicians' adherence to published guidelines.

Guideline for the Antibiotic Use in Acute Gastroenteritis

Acute gastroenteritis is common infectious disease in community in adults. This work represents an update of ‘Clinical guideline for the diagnosis and treatment of gastrointestinal infections’ that was developed domestically in 2010. The recommendation of this guideline was developed regarding the following; epidemiological factors, test for diagnosis, the indications of empirical antibiotics, and modification of antibiotics after confirming pathogen. Ultimately, it is expected to decrease antibiotic misuse and prevent antibiotic resistance.

Chromosomal Microarray Analysis as a First-Tier Clinical Diagnostic Test in Patients With Developmental Delay/Intellectual Disability, Autism Spectrum Disorders, and Multiple Congenital Anomalies: A Prospective Multicenter Study in Korea

BACKGROUND: To validate the clinical application of chromosomal microarray analysis (CMA) as a first-tier clinical diagnostic test and to determine the impact of CMA results on patient clinical management, we conducted a multicenter prospective study in Korean patients diagnosed as having developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), and multiple congenital anomalies (MCA). METHODS: We performed both CMA and G-banding cytogenetics as the first-tier tests in 617 patients. To determine whether the CMA results directly influenced treatment recommendations, the referring clinicians were asked to complete a 39-item questionnaire for each patient separately after receiving the CMA results. RESULTS: A total of 122 patients (19.8%) had abnormal CMA results, with either pathogenic variants (N=65) or variants of possible significance (VPS, N=57). Thirty-five well-known diseases were detected: 16p11.2 microdeletion syndrome was the most common, followed by Prader-Willi syndrome, 15q11-q13 duplication, Down syndrome, and Duchenne muscular dystrophy. Variants of unknown significance (VUS) were discovered in 51 patients (8.3%). VUS of genes putatively associated with developmental disorders were found in five patients: IMMP2L deletion, PTCH1 duplication, and ATRNL1 deletion. CMA results influenced clinical management, such as imaging studies, specialist referral, and laboratory testing in 71.4% of patients overall, and in 86.0%, 83.3%, 75.0%, and 67.3% of patients with VPS, pathogenic variants, VUS, and benign variants, respectively. CONCLUSIONS: Clinical application of CMA as a first-tier test improves diagnostic yields and the quality of clinical management in patients with DD/ID, ASD, and MCA.

Molecular Epidemiologic Study of a Methicillin-resistant Staphylococcus aureus Outbreak at a Newborn Nursery and Neonatal Intensive Care Unit

PURPOSE: This study aimed to investigate the molecular epidemiology of a methicillin-resistant Staphylococcus aureus (MRSA) outbreak at a newborn nursery and neonatal intensive care unit (NICU).METHODS: During the outbreak, from August to September 2017, MRSA isolates collected from neonates and medical staff underwent genotyping and screened for virulence factors. Antibiotic susceptibilities were tested.RESULTS: During the study period, 41 neonates were admitted at the nursery (n=27) and NICU (n=14). Of these, 7 had MRSA infections (skin infection [n=6] and sepsis [n=1]) and 4 were colonized with MRSA. Associated medical staff (n=32) were screened; three were nasal MRSA carriers. Staphylococcal chromosomal cassette mec (SCCmec) type II, sequence type (ST) 89, spa type t375 was found to be the skin infection outbreak causing strain, with multi-drug resistance including low-level mupirocin resistance. SCCmec type IVa, ST 72, and a novel spa type designated t17879, was the cause of MRSA sepsis. Many different types of MRSA were colonized on the neonates; however, SCCmec type IVa, ST 72, spa type t664 was colonized in both neonates and a NICU nurse. All MRSA isolates from colonized infants were positive for the Panton-Valentine leukocidin (PVL) toxin gene.CONCLUSIONS: The strain causing an outbreak of skin infections had multi-drug resistance. Also, MRSA colonized in the neonates were found to carry the PVL toxin gene. Because different strains are present during an outbreak, molecular epidemiologic studies are important to identify the outbreak strain and colonized strains which aid in effective control and prevention of future MRSA outbreaks.

Determining Genotypic Drug Resistance by Ion Semiconductor Sequencing With the Ion AmpliSeq™ TB Panel in Multidrug-Resistant Mycobacterium tuberculosis Isolates

BACKGROUND: We examined the feasibility of a full-length gene analysis for the drug resistance-related genes inhA, katG, rpoB, pncA, rpsL, embB, eis, and gyrA using ion semiconductor next-generation sequencing (NGS) and compared the results with those obtained from conventional phenotypic drug susceptibility testing (DST) in multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates. METHODS: We extracted genomic DNA from 30 pure MDR-TB isolates with antibiotic susceptibility profiles confirmed by phenotypic DST for isoniazid (INH), rifampin (RIF), ethambutol (EMB), pyrazinamide (PZA), amikacin (AMK), kanamycin (KM), streptomycin (SM), and fluoroquinolones (FQs) including ofloxacin, moxifloxacin, and levofloxacin. Enriched ion spheres were loaded onto Ion PI Chip v3, with 30 samples on a chip per sequencing run, and Ion Torrent sequencing was conducted using the Ion AmpliSeq TB panel (Life Technologies, USA). RESULTS: The genotypic DST results revealed good agreement with the phenotypic DST results for EMB (Kappa 0.8), PZA (0.734), SM (0.769), and FQ (0.783). Agreements for INH, RIF, and AMK+KM were not estimated because all isolates were phenotypically resistant to INH and RIF, and all isolates were phenotypically and genotypically susceptible to AMK+KM. Moreover, 17 novel variants were identified: six (p.Gly169Ser, p.Ala256Thr, p.Ser383Pro, p.Gln439Arg, p.Tyr597Cys, p.Thr625Ala) in katG, one (p.Tyr113Phe) in inhA, five (p.Val170Phe, p.Thr400Ala, p.Met434Val, p.Glu812Gly, p.Phe971Leu) in rpoB, two (p.Tyr319Asp and p.His1002Arg) in embB, and three (p.Cys14Gly, p.Asp63Ala, p.Gly162Ser) in pncA. CONCLUSIONS: Ion semiconductor NGS could detect reported and novel amino acid changes in full coding regions of eight drug resistance-related genes. However, genotypic DST should be complemented and validated by phenotypic DSTs.

Comparison of Four Automated Carcinoembryonic Antigen Immunoassays: ADVIA Centaur XP, ARCHITECT I2000sr, Elecsys E170, and Unicel Dxi800

BACKGROUND: Carcinoembryonic antigen (CEA) is one of the tumor markers available for evaluating disease progression status after initial therapy and monitoring subsequent treatment modalities in colorectal, gastrointestinal, lung, and breast carcinoma. We evaluated the correlations and differences between widely used, automated CEA immunoassays at four different medical laboratories. METHODS: In total, 393 serum samples with CEA ranging from 3.0 to 1,000 ng/mL were analyzed on ADVIA Centaur XP (Siemens Diagnostics, Tarrytown, NY, USA), ARCHITECT i2000sr (Abbott Diagnostics, Abbott Park, IL, USA), Elecsys E170 (Roche Diagnostics, Indianapolis, IN, USA), and Unicel DxI800 (Beckman Coulter, Fullerton, CA, USA), and the results were compared. Deming regression, Passing-Bablok regression, and Bland-Altman analyses were performed to evaluate the data correlation and % differences among these assays. RESULTS: Deming regression analysis of data from Elecsys E170 and UniCel DxI800 showed good correlation (y=3.1615+0.8970x). According to Bland-Altman plot, no statistically significant bias (−1.78 ng/mL [95% confidence interval: −4.02 to 0.46]) was observed between Elecsys E170 and UniCel DxI800. However, the relative differences of CEA concentrations between assays exceeded the acceptable limit of 30%. Regarding the agreement of positivity with cut-off value 5.0 ng/mL, ARCHITECT i2000sr and Elecsys E170 showed the highest agreement (95.2%), whereas ADVIA Centaur XP and ARCHITECT i2000sr showed the lowest agreement (70.7%). CONCLUSIONS: Agreements between automated CEA immunoassays are variable, and individual CEA concentrations may differ significantly between assays. Standardization of serum CEA concentrations and further harmonization are needed.

Incidental Identification of Plasmodium vivax During Routine Complete Blood Count Analysis Using the UniCel DxH 800

No abstract available.

Genetic Profiles of Korean Patients With Glucose-6-Phosphate Dehydrogenase Deficiency

BACKGROUND: We describe the genetic profiles of Korean patients with glucose-6-phosphate dehydrogenase (G6PD) deficiencies and the effects of G6PD mutations on protein stability and enzyme activity on the basis of in silico analysis. METHODS: In parallel with a genetic analysis, the pathogenicity of G6PD mutations detected in Korean patients was predicted in silico. The simulated effects of G6PD mutations were compared to the WHO classes based on G6PD enzyme activity. Four previously reported mutations and three newly diagnosed patients with missense mutations were estimated. RESULTS: One novel mutation (p.Cys385Gly, labeled G6PD Kangnam) and two known mutations [p.Ile220Met (G6PD São Paulo) and p.Glu416Lys (G6PD Tokyo)] were identified in this study. G6PD mutations identified in Koreans were also found in Brazil (G6PD São Paulo), Poland (G6PD Seoul), United States of America (G6PD Riley), Mexico (G6PD Guadalajara), and Japan (G6PD Tokyo). Several mutations occurred at the same nucleotide, but resulted in different amino acid residue changes in different ethnic populations (p.Ile380 variant, G6PD Calvo Mackenna; p.Cys385 variants, Tomah, Madrid, Lynwood; p.Arg387 variant, Beverly Hills; p.Pro396 variant, Bari; and p.Pro396Ala in India). On the basis of the in silico analysis, Class I or II mutations were predicted to be highly deleterious, and the effects of one Class IV mutation were equivocal. CONCLUSIONS: The genetic profiles of Korean individuals with G6PD mutations indicated that the same mutations may have arisen by independent mutational events, and were not derived from shared ancestral mutations. The in silico analysis provided insight into the role of G6PD mutations in enzyme function and stability.

Diagnostic approaches for inherited hemolytic anemia in the genetic era

Inherited hemolytic anemias (IHAs) are genetic diseases that present with anemia due to the increased destruction of circulating abnormal RBCs. The RBC abnormalities are classified into the three major disorders of membranopathies, hemoglobinopathies, and enzymopathies. Traditional diagnosis of IHA has been performed via a step-wise process combining clinical and laboratory findings. Nowadays, the etiology of IHA accounts for germline mutations of the responsible genes coding for the structural components of RBCs. Recent advances in molecular technologies, including next-generation sequencing, inspire us to apply these technologies as a first-line approach for the identification of potential mutations and to determine the novel causative genes in patients with IHAs. We herein review the concept and strategy for the genetic diagnosis of IHAs and provide an overview of the preparations for clinical applications of the new molecular technologies.

Fragment Analysis for Detection of the FLT3-Internal Tandem Duplication: Comparison with Conventional PCR and Sanger Sequencing

BACKGROUND: We evaluated a sensitive and quantitative method utilizing fragment analysis of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), simultaneously measuring mutant allele burden and length, and verified the analytical performance. METHODS: The number and allelic burden of FLT3-ITD mutations was determined by fragment analysis. Serial mixtures of mutant and wild-type plasmid DNA were used to calculate the limit of detection of fragment analysis, conventional PCR, and Sanger sequencing. Specificity was evaluated using DNA samples derived from 50 normal donors. Results of fragment analysis were compared to those of conventional PCR, using 481 AML specimens. RESULTS: Defined mixtures were consistently and accurately identified by fragment analysis at a 5% relative concentration of mutant to wild-type, and at 10% and 20% ratios by conventional PCR and direct sequencing, respectively. No false positivity was identified. Among 481 AML specimens, 40.1% (193/481) had FLT3-ITD mutations. The mutant allele burden (1.7-94.1%; median, 28.2%) and repeated length of the mutation (14-153 bp; median, 49 bp) were variable. The concordance rate between fragment analysis and conventional PCR was 97.7% (470/481). Fragment analysis was more sensitive than conventional PCR and detected 11 additional cases: seven had mutations below 10%, three cases represented conventional PCR failure, and one case showed false negativity because of short ITD length (14 bp). CONCLUSIONS: The new fragment analysis method proved to be sensitive and reliable for the detection and monitoring of FLT3-ITD in patients with AML. This could be used to simultaneously assess ITD mutant allele burden and length.

A Novel Syntaxin 11 Gene (STX11) Mutation c.650T>C, p.Leu217Pro, in a Korean Child With Familial Hemophagocytic Lymphohistiocytosis

We report the first Far Eastern case of a Korean child with familial hemophagocytic lymphohistiocytosis (HLH) caused by a novel syntaxin 11 (STX11) mutation. A 33-month-old boy born to non-consanguineous Korean parents was admitted for intermittent fever lasting one week, pancytopenia, hepatosplenomegaly, and HLH in the bone marrow. Under the impression of HLH, genetic study revealed a novel homozygous missense mutation of STX11: c.650T>C, p.Leu217Pro. Although no large deletion or allele drop was identified, genotype analysis demonstrated that the homozygous c.650T>C may have resulted from the duplication of a maternal (unimaternal) chromosomal region and concurrent loss of the other paternal allele, likely caused by meiotic errors such as two crossover events. A cumulative study of such novel mutations and their effects on specific protein interactions may deepen the understanding of how abnormal STX1 expression results in deficient cytotoxic function.

Comparison of Targeted Next-Generation and Sanger Sequencing for the BRCA1 and BRCA2 Mutation Screening

No abstract available.

Genetic–pathologic characterization of myeloproliferative neoplasms

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the proliferation of one or more myeloid lineages. The current study demonstrates that three driver mutations were detected in 82.6% of 407 MPNs with a mutation distribution of JAK2 in 275 (67.6%), CALR in 55 (13.5%) and MPL in 6 (1.5%). The mutations were mutually exclusive in principle except in one patient with both CALR and MPL mutations. The driver mutation directed the pathologic features of MPNs, including lineage hyperplasia, laboratory findings and clinical presentation. JAK2-mutated MPN showed erythroid, granulocytic and/or megakaryocytic hyperplasia whereas CALR- and MPL-mutated MPNs displayed granulocytic and/or megakaryocytic hyperplasia. The lineage hyperplasia was closely associated with a higher mutant allele burden and peripheral cytosis. These findings corroborated that the lineage hyperplasia consisted of clonal proliferation of each hematopoietic lineage acquiring driver mutations. Our study has also demonstrated that bone marrow (BM) fibrosis was associated with disease progression. Patients with overt fibrosis (grade ⩾2) presented an increased mutant allele burden (P<0.001), an increase in chromosomal abnormalities (P<0.001) and a poor prognosis (P<0.001). Moreover, among patients with overt fibrosis, all patients with wild-type JAK2/CALR/MPL (triple-negative) showed genomic alterations by genome-wide microarray study and revealed the poorest overall survival, followed by JAK2-mutated MPNs. The genetic–pathologic characteristics provided the information for understanding disease pathogenesis and the progression of MPNs. The prognostic significance of the driver mutation and BM fibrosis suggests the necessity of a prospective therapeutic strategy to improve the clinical outcome.

Potential Risk Factors Associated With Vascular Diseases in Patients Receiving Treatment for Hypertension

BACKGROUND: Currently, the hypertension (HTN) patients undergo appropriate medical treatment, and traditional risk factors are highly controlled. Therefore, potential risk factors of atherosclerotic vascular diseases (AVD) and venous thromboembolisms (VTE) in HTN should be reconsidered. We investigated thrombophilic genetic mutations and existing biomarkers for AVD or VTE in HTN patients receiving treatment. METHODS: A total of 183 patients were enrolled: AVD with HTN (group A, n=45), VTE with HTN (group B, n=62), and HTN patients without any vascular diseases (group C, n=76). The lipid profile, homocysteine (Hcy) levels, D-dimers, fibrinogen, antithrombin, lupus anticoagulant, and anti-cardiolipin antibody (aCL) were evaluated. Prothrombin G20210A, Factor V G1691A, and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C were analyzed. RESULTS: All patients revealed wild type prothrombin G20210A and Factor V G1691A polymorphisms. The frequency of MTHFR polymorphisms was 677CT (n=84, 45.9%); 677TT (n=46, 25.1%); 1298AC (n=46, 25.1%); and 1298CC (n=2, 1.1%). The MTHFR 677TT genotype tended to increase the odds ratio (OR) to AVD events in HTN patients (OR 2.648, confidence interval 0.982-7.143, P=0.05). The group A demonstrated significantly higher Hcy levels (P=0.009), fibrinogen (P=0.004), and platelet counts (P=0.04) than group C. Group B had significantly higher levels of D-dimers (P=0.0001), platelet count (P=0.0002), and aCL (P=0.02) frequency than group C. CONCLUSIONS: The MTHFR 677TT genotype and Hcy level could be potential risk factors associated with development of AVD in HTN patients receiving treatment. D-dimer and aCL might be useful to estimate the occurrence of VTE in them.

Comparison of the Real-Time PCR Tests for Factor V G1691A and Prothrombin G20210A with PCR-Restriction Fragment Length Polymorphism and Direct Sequencing Tests / 임상검사와정도관리

BACKGROUND: Factor V (FV) G1691A and prothrombin G20210A mutations are the most common targets of genetic tests for thromboembolism. This study compared the ability of real-time PCR to detect FV G1691A and prothrombin G20210A (BioSewoom, Korea) with that of PCR-restriction fragment length polymorphism (RFLP) and direct sequencing, to evaluate diagnostic equivalency. METHODS: Real-time PCR was compared with PCR-restriction fragment length polymorphism (RFLP) and direct sequencing using patients' samples as well as heterozygous and homozygous World Health Organization (WHO) reference reagent DNA. The limit of detection (LoD) for real-time PCR was determined using WHO reference reagents. RESULTS: All 141 and 156 patient samples were tested for the FV G1691A and prothrombin G20210A mutations, respectively; the results from all three methods (real-time PCR, PCR-RFLP, and direct sequencing) consistently showed that the samples were wild type. Each of the three methods showed the same results in tests using heterozygous and homozygous DNA from the WHO reference reagents. The LoD of wild type and homozygous samples was 65.16 pg/mL for FV G1691A, and 61.3 pg/mL for prothrombin G20210A. The LoD of heterozygous samples was 1,650.0 pg/mL for FV G1691A and 1,640.0 pg/mL for prothrombin G20210A. CONCLUSIONS: The real-time PCR test kits for FV G1691A and prothrombin G20210A showed reliable equivalency with PCR-RFLP and direct sequencing, and could be useful tests to detect gene polymorphisms for thromboembolism.

Assessment of the Quantitative Ability of AdvanSure TB/NTM Real-Time PCR in Respiratory Specimens by Comparison with Phenotypic Methods

Accurate quantification of mycobacterial load is important to evaluate disease severity and to monitor the course of treatment in tuberculosis (TB). We evaluated the quantitative capability of the AdvanSure TB/NTM real-time PCR kit (LG Life Science, Korea) to determine the cycle threshold (Ct) for mycobacterial burden. We retrospectively analyzed data from 108 patients whose respiratory specimens (sputums and bronchoalveolar lavage fluids) were positive for Mycobacterium tuberculosis complex (85 culture-positive and 23 culture-negative specimens). We compared Ct values with grades of acid-fast bacilli (AFB) staining, semi-quantitative colony count on solid medium, and time to positivity (TTP) in liquid and solid media. We also investigated the cutoff Ct value for predicting stain-positive status. Ct value showed significant reverse correlation with AFB staining grade (r(s)=-0.635, P<0.01). Ct value significantly decreased as the semi-quantitative counts on the solid medium increased (P<0.001), and the mean Ct value of each of the groups 1+, 2+, 3+, and 4+ were 29.0, 30.0, 27.1, and 25.5, respectively. A weak correlation between Ct value and TTP in liquid and solid media was observed (r(s)=0.468 and 0.365, respectively). A cutoff Ct value of <33.2 best predicted stain positivity, with a sensitivity of 95.0% and a specificity of 32.0%. Our findings suggest the potential use of AdvanSure TB/NTM real-time PCR kit for quantitatively determining bacterial burden, albeit with some enhancements.