Baseline glycated albumin level and risk of type 2 diabetes mellitus in Healthy individuals: a retrospective longitudinal observation in Korea.

Glycated albumin (GA) reflects glycemic status for the past three weeks. GA level demonstrates a strong correlation with HbA1c level and is used as an adjunctive biomarker for diagnosis and monitoring of type 2 diabetes mellitus (T2DM). In this study, we validated the predictive performance of baseline GA for development of T2DM in healthy individuals in Korea. From August 2013 to September 2014, the medical records of 3,771 healthy Koreans were retrospectively reviewed. Each participant was categorized into tertiles based on initial GA level. During the follow-up period through May 2020, study participants were evaluated for T2DM using HbA1c, fasting glucose level, and a self-reported diagnosis history. Baseline GA level by tertile (T1 to T3) was 10.4 ± 0.8% (mean ± SD), 12.1 ± 0.3%, and 13.7 ± 0.9%, respectively. The median follow-up was 5.97 years, during which 4.9% (186 of 3,771) of the participants developed T2DM. After adjusting for confounding factors, the hazard ratio for the development of T2DM in the highest GA level group (T3) compared to the reference group (T1) was 2.46 (95% CI, 1.7 to 3.58, p < 0.001 for trend) with a Harrell's C index of 0.80 (95% CI, 0.76 to 0.83). Also, within highest group of baseline HbA1c and FG levels, higher GA levels were associated with an increased HRs for T2DM. In conclusion, Our study confirms that the risk of T2DM increases with baseline GA level. Additional follow-up of the cohort is warranted to investigate the correlations between GA and other clinical indicators including diabetic complications.

Performance evaluation of the SMG HHV-6 Q Real-Time PCR Kit for quantitative detection and differentiation of human herpesvirus 6A and 6B.

The aim of this study was to compare the performance of the newly developed SMG HHV-6 Q Real-Time PCR Kit (SMG assay) with the RealStar HHV-6 PCR Kit (RealStar assay). The analytical sensitivity and specificity, linearity, and precision of the SMG assay were evaluated. The clinical performance of the SMG assay was assessed and compared with that of the RealStar assay using 207 clinical specimens (HHV-6A positive, n = 51; HHV-6B positive, n = 64; HHV-6A/B negative, n = 92). The limit of detection of the SMG assay was 2.92 log10 copies/mL for HHV-6A DNA and 2.88 log10 copies/mL for HHV-6B DNA. The linear range was determined to be 3.40-9.00 log10 copies/mL for both viruses. Intra- and inter-assay variability were below 5% at concentrations ranging from 4 to 9 log10 copies/mL. No cross-reactivity was observed with the 25 microorganisms included in the specificity panel. The clinical sensitivity and specificity of the SMG and RealStar assays compared to in-house polymerase chain reaction and sequencing were as follows: SMG assay, 98.0% and 100% for HHV-6A DNA, respectively, and 96.9% and 100% for HHV-6B DNA, respectively; RealStar assay, 98.0% and 100% for HHV-6A DNA, respectively, and 90.6% and 100% for HHV-6B DNA, respectively. The correlation coefficients between viral loads measured by the two assays were 0.948 and 0.975, with mean differences of 0.62 and 0.32 log10 copies/mL for HHV-6A and HHV-6B DNA, respectively. These results demonstrate that the SMG assay is a sensitive and reliable tool for the quantitative detection and differentiation of HHV-6A and HHV-6B DNA.IMPORTANCEQuantitative real-time PCR (qPCR) that can distinguish between HHV-6A and HHV-6B DNA is recommended for diagnosis of active infection. The SMG HHV-6 Q Real-Time PCR Kit (SMG assay) is a newly developed qPCR assay that can differentiate between HHV-6A and HHV-6B DNA; however, little is known about its performance. In this study, we assessed the performance of the SMG assay and compared it with that of a commercially available qPCR assay, the RealStar HHV-6 PCR Kit (RealStar assay). The SMG assay demonstrated excellent analytical sensitivity and specificity, precision, and linearity. Furthermore, the viral loads measured by the SMG assay were highly correlated with those measured by the RealStar assay. Our results suggest that the SMG assay is a useful diagnostic tool for quantitative detection and differentiation of HHV-6A and HHV-6B DNA.

Evaluation of clinical usefulness of HPV-16 and HPV-18 genotyping for cervical cancer screening.

OBJECTIVE: High-risk human papillomavirus (HR-HPV) infection is a leading cause of cervical cancer, of which human papillomavirus (HPV)-16 and HPV-18 account for about 70% of cases. Since HPV infection is common, it is important to focus on the HPV genotypes that pose the highest risk for effective cervical cancer screening. In this study, we evaluated the clinical usefulness of HPV-16/HPV-18 genotyping for cervical cancer screening. METHODS: A total of 86,022 women aged 25 years or older was analyzed in this study. Sensitivity, specificity, positive predictive value, and negative predictive value of HPV genotyping and cytology were analyzed. In addition, we subdivided participants into two groups according to cytology results, negative for intraepithelial lesion of malignancy (NILM) and atypical squamous cells of undetermined significance (ASC-US), and analyzed absolute risk (AR) and relative risk (RR) of cervical intraepithelial neoplasia (CIN) 3 or worse according to HPV genotype. RESULTS: The AR of CIN 3 or worse was 77.0 times higher in HR-HPV-positive compared to HR-HPV-negative. Compared to 12 other HR-HPV-positive, the AR of CIN 3 or worse was 4.2 times higher in HPV-16 and/or HPV-18 positive. This finding was more evident in women with NILM than in women with ASC-US. The RR of CIN 3 or worse was 7.0 in women with NILM and 4.5 in women with ASC-US. CONCLUSION: Regardless of the cytology results, the risk of CIN 3 or worse was higher in HPV-16/HPV-18 than in other HR-HPV. HPV-16/HPV-18 genotyping is recommended to screen women with a high risk of cervical cancer.

Prevalence and molecular basis of null blood group phenotypes in the Korean population: Analysis using a public database.

BACKGROUND: Null phenotypes are characterized by complete absence of all antigens within a blood group system and caused by null variants (e.g., nonsense, frameshift, initiation codon, and canonical splice site variants) in the genes encoding the antigens. Knowing the prevalence and molecular basis of null phenotypes is essential to establish a rare donor program, and the aim of this study was to reveal the prevalence and molecular basis of null phenotypes using the Korean Reference Genome Database (KRGDB) containing whole-genome sequences of 1722 Korean individuals. STUDY DESIGN AND METHODS: Population allele frequencies of null alleles in 39 blood group systems except ABO, MNS, Rh, Lewis, and FORS were obtained from the KRGDB. The prevalence of null phenotypes was calculated using Hardy-Weinberg equation. RESULTS: The prevalence of null phenotypes were estimated to be less than 0.001% in all blood group systems except JR and SID. The prevalence of the Jr(a-) and Sd(a-) phenotypes were estimated to be 0.0453% and 0.2323%, respectively. The most frequent null allele of the JR system was ABCG2*01N.01, accounting for approximately 85% of null alleles. DISCUSSION: Our approach using a public database allowed us to investigate the prevalence and molecular basis of null phenotypes in the Korean population, which will serve as a guide for establishing a rare donor program in Korea. Considering the clinical significance, Jr(a-) is an important null phenotype that should be typed in the Korean population, and molecular assays targeting the most frequent allele ABCG2*01N.01 may be useful in detecting this phenotype.

A Simple and High-Throughput LC-MS-MS Method for Simultaneous Measurement of Nicotine, Cotinine, 3-OH Cotinine, Nornicotine and Anabasine in Urine and Its Application in the General Korean Population.

Measuring nicotine metabolites is the most objective method for identifying smoke exposure. Liquid chromatography--tandem mass spectrometry (LC-MS-MS) can measure multiple metabolites and is sensitive enough to detect low concentrations of metabolites. Therefore, we developed a simple and high-throughput method for measuring nicotine, cotinine, trans-3'-hydroxycotinine (3-OH cotinine), nornicotine and anabasine for population-based studies using LC-MS-MS. Each 30 µL of urine sample was diluted with 90 µL of acetonitrile containing five deuterated internal standards. Chromatographic separation used a C18 column, and LC-MS-MS analysis was performed with a multiple reaction monitoring mode. The chromatographic run time for each sample was 6.5 min. The method was validated by evaluating selectivity, interference, limit of detection, lower limit of quantification, precision, accuracy, linearity, extraction recovery, matrix effect and carryover according to guidelines. Our methods required a short preparation time (∼20 min) while simultaneously measuring five markers for smoking status. No endogenous or exogenous interference was found. Our method showed excellent precision and accuracy: within-run coefficient of variation (CV) 2.9-9.4%, between-run CV 4.8-8.7% and bias -10.1 to 5.3%. Linear dynamic ranges were 1-10,000 ng/mL for nicotine, nornicotine and anabasine; 2-5,000 ng/mL for cotinine and 5-15,000 ng/mL for 3-OH cotinine. Extraction recovery was consistent (87-109%) across concentrations. No significant matrix effect or carryover was observed. The validated method was applied to 849 urine samples. In samples from the 125 current smokers, nicotine, cotinine, 3-OH cotinine, nornicotine and anabasine were detected in 97.6, 99.2, 98.4, 96.8 and 87.2%, respectively. No markers were detected in 93.9% of 609 nonsmokers. The overlapping detection of multiple markers made it possible to identify the smoking status even in current smokers with a low concentration of cotinine. Our LC-MS-MS method using a simple sample preparation technique is sensitive and effective for screening of smoking status in the general population.

Congenital factor V deficiency from compound heterozygous mutations with a novel variant c.2426del (p.Pro809Hisfs*2) in the F5 gene: A case report.

INTRODUCTION: Congenital factor V deficiency (FVD) is a rare bleeding disorder characterized by low or undetectable plasma factor V (FV) levels leading to mild to severe bleeding symptoms. Currently, more than 100 mutations have been reported in F5. We herein report a patient with FVD from mutations in the F5 gene. PATIENT CONCERNS: A 52-year-old man with prolonged prothrombin time and activated partial thromboplastin time corrected by mixing test on preoperative screening. His past medical or family history was not remarkable. DIAGNOSIS: Factor assays revealed a markedly reduced FV activity at 7%. Other factors were not decreased. DNA sequencing analysis to detect F5 gene mutations showed the patient was compound heterozygous for c.286G>C (p.Asp96His) and c.2426del (p.Pro809Hisfs*2). Asp96His was previously described missense mutation and Pro809Hisfs*2 was a novel deleterious mutation. INTERVENTIONS: Fresh-frozen plasma was administered to supplement FV before surgery. OUTCOMES: Subsequent factor assays revealed temporarily increased FV activity at 33%. CONCLUSION: As was the case in our patient, genotype-phenotype correlations are poor in FVD, and molecular genetic test is necessary to confirm the diagnosis.

Flow Cytometric Analysis of T Cells in Hemophagocytic Lymphohistiocytosis.

BACKGROUND: T cell immunophenotypes in patients with hemophagocytic lymphohistiocytosis (HLH) have been described. Downregulation of CD5 or CD7 on T cells has been reported in patients with Epstein-Barr virus (EBV)-positive HLH. As the utility of T cell immunophenotypes as an adjunctive diagnostic or a prognostic marker for HLH has not been evaluated, we analyzed T cell immunophenotypes in HLH patients for this purpose. METHODS: We classified 45 HLH patients into three subgroups: EBV-positive HLH (N=27), EBV-negative secondary HLH (N=15), and familial HLH (N=3). We retrospectively characterized downregulation patterns of CD5 or CD7 on activated T cells, using flow cytometry. Overall survival was estimated using Kaplan-Meier curves and compared using the log-rank test. RESULTS: An aberrant immunophenotype, including CD5 and/or CD7 downregulation on T cells, was observed in 55.6% (15/27) of the EBV-positive HLH patients and 100% of the familial HLH (3/3). Only one (1/15, 6.7%) patient with EBV-negative secondary HLH showed an aberrant loss of CD7 antigen on CD8+ T cells. The presence of an aberrant T cell immunophenotype was not related to overall survival in EBV-positive HLH and EBV-negative secondary HLH patients. CONCLUSIONS: An aberrant T cell immunophenotype may assist in discriminating EBV-negative secondary HLH and EBV-positive HLH. However, it may not be useful as a prognostic marker.

Accurate and Rapid Measurement of Glycated Hemoglobin Using HLC-723 G11 Variant Mode.

BACKGROUND: Type II diabetes mellitus causes many complications, and its prevalence continues to increase in Korea. Accurate measurement of glycated Hb (HbA1c) is important because of its usefulness in diagnosis, follow-up, and prediction of prognosis. We tested the analytical performance of the HLC-723 G11 Variant Mode (G11vr; Tosoh Bioscience, Inc., Tokyo, Japan), recently introduced to Korea, in detecting HbA1c. METHODS: We evaluated precision, linearity, carry-over, and turnaround time. Using 208 samples, including 108 flagged samples, we compared HbA1c concentrations from four analyzers through correlation analysis: G11vr, HLC-723 G8 Variant Mode (G8vr, Tosoh Bioscience), HLC-723 G11 Standard Mode (G11st, Tosoh Bioscience), and HLC-723 G8 Standard Mode (G8st, Tosoh Bioscience). We used HPLC mass spectrometry (MS) and capillary electrophoresis (CE) to confirm the HbA1c concentrations of 15 additional known Hb variant samples. RESULTS: Repeatability (% CV) in measuring low- and high-concentration controls was 0.57% and 0.35%, respectively; within-laboratory precision was 0.86% and 0.69%, respectively. In a linearity test, the coefficient of determination was 0.9999 (measurement range: 3.64% to 18.59%) for HbA1c. The correlations between G11vr and other analyzers were weaker for flagged samples than for non-flagged samples. The carry-over effect was less than 0.4%. Turnaround time for a single sample was lower in G11vr (one minute) than in G8vr (1.6 minutes). For 15 samples with Hb variants, G11vr HbA1c results were more similar than those of other analyzers to HPLC-MS and CE results. CONCLUSIONS: G11vr showed adequate performance and rapid turnaround time in measuring HbA1c.

Comparative Evaluation of QuantiFERON-TB Gold In-Tube and QuantiFERON-TB Gold Plus in Diagnosis of Latent Tuberculosis Infection in Immunocompromised Patients.

QuantiFERON-TB Gold Plus (QFT-Plus) is a new-generation QuantiFERON-TB Gold In-Tube (QFT-GIT) assay which has two antigen-coated tubes called TB1, which contains long peptides derived from ESAT-6 and CFP-10, and TB2, which contains the same components as TB1 and additional short peptides which potentially stimulate CD8+ T cells through the presentation of major histocompatibility complex class I. This is the first study to compare QFT-Plus and QFT-GIT for use in the diagnosis of latent tuberculosis infection (LTBI) among immunocompromised patients in the Republic of Korea. Among 317 consecutive patients who underwent screening for LTBI before solid organ or hematopoietic stem cell transplantation and tumor necrosis factor alpha inhibitor treatment, LTBI was identified in 92 (29.0%) and 88 (27.8%) patients by QFT-GIT and QFT-Plus, respectively. The rate of concordance between QFT-GIT and QFT-Plus was 93.7% (κ value, 0.860), and the indeterminate rate (3.2%) was similar between QFT-GIT and QFT-Plus. Of 20 (6.3%) samples with discordant results, 11 (55.0%) and 7 (35.0%) were positive by QFT-GIT alone and QFT-Plus alone, respectively, and 2 (15.0%) were indeterminate by each assay. The interferon gamma level in samples with discordant results ranged from 0.39 to 1.10 IU/ml, except for one sample, in which the gamma interferon level was 2.97 IU/ml only in TB2. Conclusively, there was a high degree of agreement between the results of QFT-GIT and QFT-Plus for the screening of immunocompromised patients for LTBI. The reactivity in TB2 contributed substantially to the difference between QFT-GIT and QFT-Plus, particularly in solid organ transplant candidates. The significance of the discrete responses in TB1 and TB2 of QFT-Plus needs to be explored further by means of an immunological and clinical approach in different patient groups and clinical settings.

Performance evaluation of the QMAC-dRAST for staphylococci and enterococci isolated from blood culture: a comparative study of performance with the VITEK-2 system.

Objectives: To evaluate the performance of a rapid antimicrobial susceptibility testing (AST) platform based on microfluidic chip technology, the QMAC-dRAST, which enables AST from colony isolates or positive blood culture broth (PBCB), and to compare the performance of the QMAC-dRAST for staphylococci and enterococci with that of the VITEK-2 system based on reference broth microdilution (BMD). Methods: A total of 110 staphylococcal and enterococcal isolates from blood cultures were included. AST was performed directly using the QMAC-dRAST with PBCB. Thereafter, colony isolates derived from subculture of PBCB were used for the QMAC-dRAST, the VITEK-2 system and BMD. Results: The overall agreement between the QMAC-dRAST with PBCB and BMD was 91.5%. There were 1.2% very major errors (VMEs), 4.3% major errors (MEs) and 5.4% minor errors (mEs). The QMAC-dRAST with colony isolates yielded 94.6% agreement and error rates of 1.0% VMEs, 1.8% MEs and 4.0% mEs. The VITEK-2 system showed 96.2% agreement and error rates of 2.3% VMEs, 0.5% MEs and 2.6% mEs. The incubation time in the QMAC-dRAST was significantly shorter than in the VITEK-2 system (median of 6 versus 10 h; P < 0.0001). Conclusions: The QMAC-dRAST system provided rapid results and represents an alternative to conventional AST methods. The QMAC-dRAST with colony isolates produced more reliable results for staphylococci and enterococci than the QMAC-dRAST with PBCB. The QMAC-dRAST system also performed comparably to BMD and the VITEK-2 system.