[Show abstract][Hide abstract] ABSTRACT: Most cases with congenital hypothyroidism (CH) are usually sporadic, while about 20% of the cases are caused by genetic defects. Little information is available regarding the mutation incidence and genetic heterogeneity of CH in Koreans. We aimed to determine the mutation incidence of CH in newborn screenings (NBS) and to evaluate the frequency and spectrum of mutations underlying CH.
Preview · Article · Jan 2016 · Annals of Laboratory Medicine
[Show abstract][Hide abstract] ABSTRACT: Newborn screening (NBS) has been effective for detecting asymptomatic newborns with inherited metabolic diseases and has facilitated early clinical intervention, which has resulted in significant decreases in the rates of morbidity and mortality caused by these diseases. The outcome of the NBS program heavily depends on technological advances. Since Dr. Robert Guthrie developed a bacterial inhibition assay to screen for metabolic diseases in the early 1960s, use of the NBS program has spread to many countries. Tandem mass spectrometry (TMS) was a second major technological breakthrough that has allowed screening to be extended to disorders of fatty acid and organic acid metabolism as well as to those of amino acid metabolism, and recently screening has also been expanded to include lysosomal storage diseases. TMS can detect multiple analytes rapidly and simultaneously and is currently applied to nearly 80% of the newborn population in Korea. Next-generation sequencing (NGS) technology could be another major breakthrough to improve the current NBS program. To integrate NGS into the NBS program, various considerations about its analytical validity, clinical validity, clinical utility, and ethical, legal, and social implications should be addressed on the basis of population screening. Here, the authors review population screening criteria, the current status of NBS, and recent advances in NGS. In addition, we discuss the practical and ethical issues, opportunities, and challenges regarding the implementation of NGS in NBS.
[Show abstract][Hide abstract] ABSTRACT: Background
Accurate measurement of BCR–ABL1 fusion transcripts is critical for therapeutic stratification in patients with chronic myelogenous leukemia (CML). Previous studies have reported the variable performance of the existing quantitative reverse transcription polymerase chain reaction (RQ-PCR). Here, we developed a one-step multiplex RQ-PCR method based on the catalytically cleavable fluorescence probe technology for quantification of BCR–ABL1 transcripts.
Performance was evaluated with respect to the limit of detection (LoD), linearity, precision, and comparison on the VIIA7 Real-Time PCR system. Multiplex RQ-PCR was performed by the one-step and one-well reaction without the hands-on time.
Our assay showed a LoD of 1.5 pg with linearity in the range of more than 4 logs of dilution. Intraassay, interassay, and total percent CVs at the concentration of 150 ng were 12.8%, 22.6%, and 28.0%, respectively. The assay correlated well with Asuragen's BCR/ABL1 Quant™ kit over a 6 log concentration range (r = 0.9967).
Our assay demonstrated comparable performance characteristics in comparison with previous RQ-PCR based on the TaqMan probe technology. We conclude that our method could be a reliable tool in the clinical setting.
No preview · Article · Feb 2014 · Clinica chimica acta; international journal of clinical chemistry
[Show abstract][Hide abstract] ABSTRACT: Autosomal dominant non-syndromic hearing loss (AD-NSHL) is one of the most common genetic diseases in human and is well-known for the considerable genetic heterogeneity. In this study, we utilized whole exome sequencing (WES) and linkage analysis for direct genetic diagnosis in AD-NSHL. The Korean family had typical AD-NSHL running over 6 generations. Linkage analysis was performed by using genome-wide single nucleotide polymorphism (SNP) chip and pinpointed a genomic region on 5q31 with a significant linkage signal. Sequential filtering of variants obtained from WES, application of the linkage region, bioinformatic analyses, and Sanger sequencing validation identified a novel missense mutation Arg326Lys (c.977G>A) in the POU homeodomain of the POU4F3 gene as the candidate disease-causing mutation in the family. POU4F3 is a known disease gene causing AD-HSLH (DFNA15) described in 5 unrelated families until now each with a unique mutation. Arg326Lys was the first missense mutation affecting the 3(rd) alpha helix of the POU homeodomain harboring a bipartite nuclear localization signal sequence. The phenotype findings in our family further supported previously noted intrafamilial and interfamilial variability of DFNA15. This study demonstrated that WES in combination with linkage analysis utilizing bi-allelic SNP markers successfully identified the disease locus and causative mutation in AD-NSHL.
[Show abstract][Hide abstract] ABSTRACT: Glanzmann thrombasthenia (GT) is an autosomal recessive bleeding disorder caused by defective glycoprotein, αIIb and β3, encoded by ITGA2B and ITGB3 genes, respectively. We herein describe four unrelated Korean patients with genetically confirmed GT. Two patients were homozygous for c.1913+5G>T (IVS11+5G>T) mutation of ITGB3 with a signature of founder effect. The other two patients were compound heterozygous for two mutations of ITGA2B: c.[2333A>C];[2975delA] (p.[Q778P];[E992Gfs*30]) and c.[1750C>T];[2333A>C] (p.[R584X];[Q778P]). The c.2975delA mutation was a novel frameshift mutation of ITGA2B. Although from a limited number of patients, these results suggests c.1913+5G>T of ITGB3 is a recurrent mutation in Korean patients with GT.
No preview · Article · Aug 2012 · Pediatric Blood & Cancer
[Show abstract][Hide abstract] ABSTRACT: To determine first whether there was a clear relationship between concentrations of the active metabolite of oxcarbazepine (OXC), 10-hydroxycarbamazepine (OHC), and dose adjusted for weight, and second, whether the clearance of OHC was influenced by comedication with enzyme-inducing antiepileptic drugs (EIAED).
We analyzed 254 cases (patients 3-80 years of age) of OXC therapeutic drug monitoring, retrospectively. The cases were categorized into OXC monotherapy (n = 78), OXC in combination with EIAED (n = 73), and OXC in combination with non-EIAED (n = 103). The serum OHC concentrations of predose samples were measured by high-performance liquid chromatography. A population pharmacokinetic model was developed using NONMEM.
The mean ± SD serum concentration of OHC was 14.47 ± 8.28 μg/mL at a mean daily dose of 16.22 ± 7.99 mg/kg. The serum concentration of OHC was correlated with the OXC dose per body weight (r = 0.6005; P < 0.0001). No association was found between OHC concentration and patient age, weight, sex, or seizure type. The concentration-to-dose ratio on OXC in combination with EIAED was significantly lower than that on OXC monotherapy (P = 0.002) or OXC in combination with non-EIAED (P < 0.0001). In population pharmacokinetic modeling, the apparent clearance of OHC was higher by 31.2% in combination with EIAED than in other groups.
The serum concentration of OHC was statistically significantly correlated with the dose of OXC and negatively correlated with comedication of EIAED. Population pharmacokinetic analysis showed that the apparent clearance of OHC increased with comedication with EIAEDs.
No preview · Article · Jan 2012 · Clinical neuropharmacology
[Show abstract][Hide abstract] ABSTRACT: The activated partial thromboplastin time (aPTT) is a widely used coagulation screening test in routine laboratories. The aPTT level in the control population varies and is reflected by the reference interval. However, there have been no studies to investigate the coagulation status determining the variability of the aPTT. The aim of this study was to investigate the coagulation factor activities underlying the variability of aPTT in the population. The study participants were reference individuals with prothrombin time and aPTT within reference intervals. The aPTT was determined using STA-PTT Automate (Diagnostica Stago, Asnieres, France; local reference interval, 29.1-41.9 s). Those with aPTT within the marginal ranges of reference interval were selected for factor assays. We defined the lower marginal group as the lowest 10 percentile of reference interval (29.1-30.9 s) and the upper marginal group as the highest 10 percentile (38.0-41.9 s). Activities of factor II, V, VIII, IX, X, XI, and XII were determined in both groups. The lower marginal and upper marginal groups consisted of 220 and 209 individuals, respectively. All coagulation factors were significantly higher in the lower marginal than in the upper marginal group (P = 0.0127 for factor II and P < 0.0001 for the others). Multiple logistic regression analyses revealed factor XII and VIII were two strongest contributors determining the aPTT level, whereas factor XI was not significantly different between the groups (P = 0.095). This study firstly demonstrated significantly different coagulation factor activities underlying the variability of aPTT in reference individuals. The results suggested the possibility of disease association or phenotypic contribution of variable coagulation activities in the population.
No preview · Article · Jan 2012 · Blood coagulation & fibrinolysis: an international journal in haemostasis and thrombosis
[Show abstract][Hide abstract] ABSTRACT: Blood culture-negative infective endocarditis (CNE) can be a diagnostic dilemma. Herein, we report a case of CNE caused by Haemophilus parainfluenzae identified only via 16S rRNA sequence analysis directly from valve tissue. A 17-year-old boy presented with high spiking fever for one month. Pansystolic murmur (Grade III) and vegetation (0.65×0.26 cm and 0.62×0.55 cm) on the anterior mitral valve leaflet via transesophageal echocardiogram suggested the diagnosis of infective endocarditis (IE). However, blood culture performed on admission was negative even after 2 weeks of incubation. Gram stain and culture of a direct tissue specimen failed to identify causative microorganism, while 16S rRNA gene sequences (548 bp) showed 100% identity with those of Haemophilus parainfluenzae (GenBank: FJ939586.1). The 16S rRNA sequence analysis with a direct tissue specimen might be useful in cases of CNE.
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to investigate the epidemiologic characteristics of extrapulmonary tuberculosis (EPTB) in Korea. In addition, the results of culture-confirmed (CC) EPTB were compared with those of clinically-diagnosed (CD) EPTB.
[Show abstract][Hide abstract] ABSTRACT: Streptococcus suis infection is an emerging zoonosis in Asia. The most common disease manifestation is meningitis, which is often associated with hearing loss and cochleovestibular signs. S. suis infection in humans mainly occurs among risk groups that have frequent exposure to pigs or raw pork. Here, we report a case of S. suis meningitis in a 67-yr-old pig carcass handler, who presented with dizziness and sensorineural hearing loss followed by headaches. Gram-positive diplococci were isolated from cerebrospinal fluid (CSF) and blood cultures and showed gray-white colonies with α-hemolysis. S. suis was identified from CSF and blood cultures by using a Vitek 2 system (bioMérieux, France), API 20 STREP (bioMérieux), and performing 16S rRNA and tuf gene sequencing. Even after receiving antibiotic treatment, patients with S. suis infection frequently show complications such as hearing impairment and vestibular dysfunction. To the best of our knowledge, this is the first case of S. suis meningitis in Korea. Prevention through public health surveillance is recommended, especially for individuals who have occupational exposures to swine and raw pork.
Full-text · Article · Jul 2011 · The Korean Journal of Laboratory Medicine
[Show abstract][Hide abstract] ABSTRACT: Fibrin-related markers (FRM) such as fibrin monomer (FM) and D-dimer (DD) are considered useful biological markers for the diagnosis of disseminated intravascular coagulation (DIC). However, no studies on the diagnostic performance of different FRMs have been published in Korea. The aim of this study was to evaluate the diagnostic performance of FM for DIC in comparison with DD.
The reference limit of FM was determined based on plasma sample data obtained from 210 control individuals. To evaluate diagnostic performance, FM data from the plasma samples of 139 patients with DIC-associated diseases were obtained for DIC scoring. FM was measured by immunoturbidimetry using STA-LIATEST FM (Diagnostica Stago, France). Patients were classified according to the DIC score as non-DIC, non-overt DIC, or overt DIC. ROC curve analyses were performed.
The reference limit in the control individuals was determined to be 7.80 µg/mL. Patients with DIC-associated diseases were categorized as non-DIC (N=43), non-overt DIC (N=80), and overt DIC (N=16). ROC curve analyses showed that the diagnostic performance of FM was comparable to DD in both non-overt DIC and overt DIC (P=0.596 and 0.553, respectively). In addition, FM had higher sensitivity, specificity, positive predictive value, and negative predictive value than DD for differentiating overt DIC from non-DIC.
This study demonstrated that the diagnostic performance of FM for DIC was comparable to DD. FM might be more sensitive and more specific than DD in the diagnosis of overt DIC, but not non-overt DIC.
Preview · Article · Jul 2011 · The Korean Journal of Laboratory Medicine
[Show abstract][Hide abstract] ABSTRACT: The purpose of the present study was to conduct a comprehensive evaluation of clinical and metabolic factors in order to determine the characteristics of urolithiasis in a Korean population, compared with other ethnic groups. In addition, clinical and metabolic factors associated with calcium oxalate (CaOx) and uric acid (UA) stone formation were compared.
A total of 211 Korean patients with urolithiasis were analysed. Biochemical components in 24-hour urine were determined and the relative supersaturation (RSS) was calculated using the EQUIL 3 software program. Physical analysis of stone composition using Fourier Transform-Infrared spectrometry (FT-IR), blood chemistry, and demographics were also investigated.
A previous history of urolithiasis and male gender were found to be clinical risk factors related to urolithiasis. Metabolic abnormalities, including hypercalciuria, low urine volume, natriuresis, hypocitraturia, and hyperoxalaturia were commonly found in 24-hour urine. Korean patients had higher calcium, lower citrate, lower phosphate, lower urine volume, and higher RSS with respect to UA than Caucasian patients. Patients with CaOx stone formation (n = 100) were younger and excreted a higher level of calcium and higher UA at a higher pH than patients with UA stones (n = 37). A significant difference in RSS was observed with respect to CaOx, while there was no significant difference in RSS with respect to UA between them.
Metabolic abnormalities, including hypercalciuria, low urine volume, natriuresis, hypocitraturia, and hyperoxalaturia were important findings in Korean patients with urolithiasis. In addition, clinical and metabolic characteristics of CaOx stone formers differed in comparison with UA stone formers.
No preview · Article · Jun 2011 · Scandinavian journal of clinical and laboratory investigation
[Show abstract][Hide abstract] ABSTRACT: Clopidogrel has been widely used to prevent recurrent ischemia in patients with acute coronary syndrome (ACS). However, inter-individual variability in response to clopidogrel has been a problem in the clinical setting. The aim of the present study was to investigate the frequency of clopidogrel resistance and to determine the clinical, pharmacokinetic, and pharmacogenetic factors for clopidogrel resistance in Korean patients with ACS.
Clinical information, such as the underlying diseases and concurrent medications, of 114 patients with ACS who received clopidogrel therapy was studied. The degree of inhibition of platelets was assessed using the VerifyNow assay (Accumetrics, USA). The patients who showed less than 20% inhibition of platelets were defined as non-responders to clopidogrel treatment. Steady state plasma concentrations of clopidogrel were measured using HPLC/tandem mass spectrometry. CYP2C19 genotyping was also performed.
A wide inter-individual variability was observed in platelet inhibition (0-76%); 56 patients (49%) showed less than 20% inhibition. There were no differences between the patients' history of diabetes mellitus and concurrent medications as well as the plasma concentrations of clopidogrel of the responders and non-responders. CYP2C19 variants, including CYP2C19*2 and CYP2C19*3, were more commonly observed in the non-responders than in the responders (P value < 0.0001).
The response to clopidogrel was highly variable in Korean patients with ACS. The results of the present study confirmed that the genetic polymorphism of CYP2C19 could be important in clopidogrel response. However, further studies are required to investigate other likely factors involved in clopidogrel resistance.
Full-text · Article · Apr 2011 · The Korean Journal of Laboratory Medicine
[Show abstract][Hide abstract] ABSTRACT: X-linked liver glycogenosis (XLG) is caused by a mutation in the PHKA2 gene which encodes the alpha subunit of phosphorylase kinase (PHK). Although XLG is not a rare disease, there have been no reports of PHKA2 mutations in Koreans. A 5-year-old boy presented with easy fatigability and hepatomegaly. Liver enzymes were increased and liver histology revealed deposition of glycogen. The PHK activity was markedly decreased compared to control. No amplification was observed at exon 8 of the PHKA2 gene, as a result of the deletion of exon 8. Sequence analysis revealed a hemizygous deletion in the region of exon 8 (c.717+781_864+225del1626). The patient was diagnosed as having XLG I. To the best of our knowledge, this is the first report of XLG I in Koreans.
No preview · Article · Mar 2011 · Annals of clinical and laboratory science