Immunogenicity of Third-dose BNT162b2 mRNA Vaccine Following Two Doses of ChAdOx1 in Health Care Workers: A Prospective Longitudinal Study.

Following the original severe acute respiratory syndrome coronavirus 2 strain (Wuhan-Hu-1) in December 2019, the Delta variant in May 2021 and the Omicron variant in December 2021 were classified as variants of concern. The pandemic has been ongoing for more than two years, and the three-dose vaccination rate has reached approximately 50% in Korea. We analyzed anti-S antibodies (Abs) and neutralizing Abs (NAbs) in 32 healthcare workers at a university hospital, focusing on the first to third doses of ChAdOx1-ChAdOx1-BNT162b2, which is the most common vaccination regimen in Korea. Antibodies were analyzed at eight time points according to the vaccine regimen. The first to third doses of ChAdOx1-ChAdOx1-BNT162b2 produced high Ab concentrations; NAb concentrations after the third dose were predicted to remain high for a longer period than those after the first and second doses. The effectiveness of a second dose of ChAdOx1 in the real world was demonstrated by analyzing samples collected during an outbreak that occurred in the study period, 4-5 months after the second dose. The relative risk ratio was 88.0%, and the efficacy of the second ChAdOx1 dose was 12.0% (P<0.05). Therefore, maintaining appropriate Ab concentrations through regular vaccination will help protect against coronavirus disease-19.

Clinical, biochemical, and genetic analysis of a Korean neonate with hereditary tyrosinemia type 1.

BACKGROUND: Hereditary tyrosinemia type 1 (HT1; MIM 276700) is caused by mutations in the fumarylaceto-acetate hydrolase (FAH) gene, and is the most severe disorder associated with the tyrosine catabolic pathway. HT1 is a very rare disorder and no genetically confirmed case of HT1 in Korea has yet been reported. In this study, we present a Korean neonate with clinical and biochemical features of HT1. METHODS: A female neonate was admitted to our hospital for further work-up of an abnormal newborn screening test. We analyzed amino acids and organic acids in the patient's blood and urine. To confirm the presence of the genetic abnormality, all the coding exons of the FAH gene and the flanking introns were amplified by polymerase chain reaction (PCR). RESULTS: The patient's newborn screening test revealed increased concentrations of methionine and tyrosine. Subsequent urine organic acid analysis showed increased urinary excretion of 4-hydroxyphenyllactate, 4-hydroxyphenylpyruvate, succinate, and succinylacetone. Gap-PCR and sequence analysis of the FAH gene revealed a homozygous large deletion mutation encompassing exons 12-14. The patient's parents were not consanguineous but were heterozygous carriers of the same mutation. CONCLUSIONS: The patient had a novel, large deletion mutation of FAH and is the first report of genetically confirmed HT1 in Korea.

Mutation analysis of PAH gene and characterization of a recurrent deletion mutation in Korean patients with phenylketonuria.

Phenylketonuria (PKU; MIM 261600) is an autosomal recessive metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH; EC 1.14.16.1). Point mutations in the PAH gene are known to cause PKU in various ethnic groups, and large deletions or duplications account for up to 3% of the PAH mutations in some ethnic groups. However, a previous study could not identify approximately 14% of the mutant alleles by sequence analysis in Korean patients with PKU, which suggests that large deletions or duplication might be frequent causes of PKU in Koreans. To test this hypothesis, we performed multiplex ligation-dependent probe amplification (MLPA) for the identification of uncharacterized mutant alleles after PAH sequence analysis of 33 unrelated Korean patients with PKU. Bi-directional sequencing of the PAH exons and flanking intronic regions revealed 27 different mutations, including four novel mutations (two missense and two deletion mutations), comprising 57/66 (86%) mutant alleles. MLPA identified a large deletion that encompassed exons 5 and 6 in four patients, another large deletion that extended from exon 4 to exon 7 in one patient, and a duplication of exon 4 in one patient. Chromosomal walking characterized the deletion breakpoint of the most common large deletion that involved exons 5 and 6 (c.456_706+138del). The present study shows that the allelic frequency of exon deletion or duplication is 9% (6/66) in Korean PKU patients, which suggests that these mutations may be frequent causes of PKU in Korean subjects.

A pulsed amperometric detection method of galactose 1-phosphate for galactosemia diagnosis.

Galactose 1-phosphate uridyltransferase deficiency causes the accumulation of galactose and galactose 1-phosphate (Gal 1-P) in the blood. We describe a new pulsed amperometric detection method for determining Gal 1-P levels as a pathognomic marker for the diagnosis of galactosemia. The method uses high-performance anion-exchange chromatography with pulsed amperometric detection. In an anion-exchange column, the analytes were separated in 5 min by the eluent mixture of 40 mM NaOH and 40 mM Na(2)CO(3). The detection limit (signal to noise ratio of 3) to Gal 1-P was 30 microg/dL. The linear dynamic range was 3.0-50 mg/dL (r(2)=0.9999). The mean recoveries of Gal 1-P for intra- and interday assays were 97.55-103.78%. This method clearly separated the type I galactosemia patients from the normal group and is a practical procedure for the rapid diagnosis of galactosemia.

Application of albumin-adjusted ischemia modified albumin index as an early screening marker for acute coronary syndrome.

BACKGROUND: Existing cardiac markers are not sensitive for reversible myocardial ischemia. Ischemia modified albumin (IMA) has recently been shown to be an early and sensitive marker of myocardial ischemia. We established a newly standardized, albumin-adjusted IMA index that was more sensitive and accurate than the conventional IMA value. METHODS: We enrolled 413 consecutive patients with symptoms suggestive of acute coronary syndrome (ACS). All patients were classified to either the ACS group (n=129) or 4 other groups (n=284). The ideal cutoff value of IMA was calculated by the receiver operating characteristic (ROC) curve analysis. The albumin-adjusted IMA index was calculated from the results of correlation assay between serum albumin concentration and IMA value and re-applied. RESULTS: The sensitivity and specificity of IMA for ACS were 93.0% and 35.6%, respectively, at 85.0 U/ml. IMA had a negative linear relationship with serum albumin and albumin-adjusted IMA index was calculated by using the following equation [IMA index=serum albumin conc. (g/dl) x 23+IMA (U/ml)-100]. The sensitivity and specificity were 98.4% and 34.5%, respectively, at IMA index of 83.4. CONCLUSIONS: The use of the calculated albumin-adjusted IMA index is recommended to increase the sensitivity of the ACS diagnosis although IMA is a sensitive marker for the identification of ACS.

An engineered fibrinogen variant AαQ328,366P does not polymerise normally, but retains the ability to form α cross-links.

A fibrin clot is stabilised through the formation of factor XIIIa-catalysed intermolecular ε-lysyl-γ-glutamyl covalent cross-links between α chains to form α polymers and between γ chains to form γ dimers. In a previous study we characterised fibrinogen Seoul II, a heterozygous dysfibrinogen in which a cross-linking acceptor site in Aα chain, Gln328, was replaced with Pro (AαQ328P). Following on the previous study, we investigated whether the alteration of Gln residues Aα328 and Aα366 affects fibrin polymerisation and α chain cross-linking. We have expressed three recombinant fibrinogens: AαQ328P, AαQ366P, and AαQ328,366P in Chinese hamster ovary cells, purified these fibrinogens from the culture media and performed biochemical tests to see how the introduced changes affect fibrin polymerisation and α chain cross-linking. Thrombin-catalysed fibrin polymerisation of all variants was impaired with the double mutation being the most impaired. In contrast, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot analysis showed α polymer formation with all three engineered proteins. This study demonstrates that AαQ328 and AαQ366 are important for normal fibrin clot formation and in the absence of residues AαQ328 and AαQ366, other Gln residues in the α chain can support FXIIIa-catalysed fibrin cross-linking.

Identification of PRODH mutations in Korean neonates with type I hyperprolinemia.

BACKGROUND: Hyperprolinemia is a rare inherited metabolic disorder characterized by a high proline level in blood and/or urine and various neuropsychiatric symptoms. Type I hyperprolinemia is caused by a proline oxidase deficiency, which is encoded by the PRODH gene on chromosome 22q11. Herein, we present a study of Korean patients with type I hyperprolinemia who were diagnosed during newborn screening by tandem mass spectrometry and confirmed by molecular analysis. METHODS: Four neonates were referred to our hospital for workup of high proline levels in newborn screening test. We analyzed the biochemical findings and the PRODH gene was amplified by long-range PCR to confirm molecular genetic abnormalities. RESULTS: All patients had high plasma proline levels, ranging from 742 to 1192 µmol/L (reference range, 77.4 - 244.6 µmol/L). In molecular analysis, 4 disease-associated mutant alleles were identified: c.1414G>A (p.A472T), c.1279G>A (p.V427M), c.1357C>T (p.R453C) and c.1562A>G (p.Q521R). All mutations were missense and c.1279G>A included the majority of mutant alleles. No relationships between type of mutation and clinical outcomes were observed. CONCLUSION: We found that distinct molecular alterations of the PRODH gene result in abnormal proline levels. Newborn screening and molecular analysis are necessary to identify patients before clinical expression of metabolic disease.

Three patients with glycogen storage disease type II and the mutational spectrum of GAA in Korean patients.

BACKGROUND: Glycogen storage disease II (GSD II) is caused by a deficiency of acid alpha-1,4-glucosidase and mutations in the GAA gene encoding this enzyme which are responsible for the pathogenesis of GSD II. Our goal was to determine the mutational spectrum in the GAA gene in Korean patients with GSD II. METHODS: Three patients with GSD II were recruited based on clinical and biochemical findings. Alpha-1,4-glucosidase activity was determined and the GAA gene sequence was analyzed by PCR and sequencing. We also collected information about the genotypes of Korean patients with GSD II from the medical literature. RESULTS: We identified six mutant alleles among the three GSD II patients: c.875A>G, c.1156C>T, c.1316T>A, c.1857C>G, and c2407_2412del7. c.1156C>T (Q386*) is a novel mutation. A comprehensive review of the literature revealed that a total of 29 mutant alleles, including 15 different mutations (10 missense, 3 deletion, and 2 nonsense mutations), were previously identified in 15 Korean GSD II patients. c.1316T>A (p.M439K) and c.1857C>G (p.S619R) were the most common mutations and accounted for 36.6% of the total mutant alleles. CONCLUSIONS: We identified three GSD II patients and investigated the mutational spectrum in GAA in Korean patients with GSD II. Our results indicate that common mutations in the GAA gene vary according to ethnic background.

Fibrinogen residue γAla341 is necessary for calcium binding and 'A-a' interactions.

The fibrinogen γ-module has several important sites relating to fibrinogen function, which include the high affinity calcium binding site, hole 'a' that binds with knob 'A', and the D:D interface. Residue γAla341, which is located in the vicinity of these sites, is altered in three variant fibrinogens: fibrinogen Seoul (γAla341Asp), Tolaga Bay (γAla341Val), and Lyon III (γAla341Thr). In order to investigate the impaired polymerisation of fibrinogens γAla341Asp and γAla341Val to understand the role of γAla341 in fibrin polymerisation and fibrinogen synthesis, we have expressed γAla341Asp and γAla341Val in Chinese hamster ovary (CHO) cells, purified these fibrinogens from the culture media and performed biochemical tests to elucidate their function. Expression in CHO cells was similar for these variants. For both variants the kinetics of thrombin-catalysed FpA release was not different from normal fibrinogen, while FpB release was slower than that of normal. Thrombin-catalysed polymerisation of both variants was dependent on the calcium concentration. At physiologic calcium (1 mM) the variants showed impaired polymerisation with a longer lag period and a slower Vmax than normal fibrinogen. Scanning electron micrographs showed the clots were less organised than normal, having thicker and more twisted fibers, and larger pores. Analysis by SDS-PAGE showed that factor XIIIa-catalysed γ and α chain cross-linking was delayed, and plasmin-catalysed lysis was not reduced by the presence of 5 mM calcium or 5 mM GPRP (Gly-Pro-Arg-Pro). Our data indicate that fibrinogen residue γAla341 is important for the proper conformation of the γ-module, maintaining calcium-binding site and 'A-a' interactions.

[A case of central nervous system myelomatosis with complex chromosome aberrations].

Involvement of the central nervous system is very uncommon in multiple myeloma, observed in approximately 1% of the multiple myeloma patients. We report a case of central nervous system myelomatosis with complex chromosome aberrations in a 62-yr-old female patient, who had previously been diagnosed as multiple myeloma. Fluorescent in situ hybridization revealed 13q deletion, p53 gene deletion and IGH/FGFR3 rearrangement and chromosomal study showed complex chromosome aberrations. After four cycles of chemotherapy, the patient was admitted to the hematology department with severe headache. Plasma cells were found in the cerebrospinal fluid (CSF), and CSF immunoelectrophoresis revealed abnormal precipitin arcs against anti-IgG and anti-lambda antisera. She was given systemic chemotherapy and eight courses of intrathecal chemotherapy, which cleared plasma cells in the CSF. Two months later, she was given autologous stem cell transplantation. Three months after stem cell transplantation, central nervous system myelomatosis progressed to plasma cell leukemia and two months later, the patient expired.

[A case of multiple myeloma showing marked differences in serum IgG levels between protein electrophoresis and turbidimetry].

We report a case of multiple myeloma showing marked differences in serum Immunoglobulin G (IgG) levels between serum protein electrophoresis and turbidimetry. A 47-yr old man was admitted to our hospital due to severe back pain and diagnosed as having IgG-kappa type multiple myeloma. Serum protein level was 14.4 g/dL at the time of diagnosis. Serum IgG level was 8.5 g/dL by serum protein electrophoresis, but 11.6 g/dL by turbidimetry. The patient's clinical conditions had improved after receiving VAD (vincristine, adriamycin, dexamethasone) and VTD (vincristine, thalidomide, dexamethasone) chemotherapy and there were no differences in IgG levels between electrophoresis and turbidimetry when serum IgG levels were less than 3.0 g/dL. According to this, we considered that both protein electrophoresis and turbidimetry should be needed to quantify serum immunoglobulins for diagnosis and follow-up of the patients with monoclonal gammopathy.

[Utility of D-dimer assay for diagnosing pulmonary embolism: single institute study].

BACKGROUND: Pulmonary embolism (PE) presents with diverse non-specific signs and symptoms and its diagnosis mainly depends on diagnostic imaging tests which are laborious and not cost-effective, and only a small proportion of patients with suspected PE actually have the disease. The aim of this study was to analyze the utility of D-dimer test for diagnosing PE by categorizing patients into 'PE likely' and 'PE unlikely' groups using Wells score for clinical probability. METHODS: One hundred forty consecutive patients with clinically suspected PE, in whom D-dimer and imaging tests were performed were enrolled. Dignosis of PE was made when the imaging tests were positive. Wells scores were retrospectively assigned and the dignostic utility of D-dimer test was analyzed. RESULTS: Of the 140 patients studied, D-dimer test was positive in 97 and diagnostic imaging tests revealed PE, deep vein thrombosis (DVT), and PE+DVT in 24, 3, and 7 patients, respectively. For the diagnosis of PE, D-dimer test with cutoff value of > or =230 ng/mL showed sensitivity, specificity, and negative predictive value of 96.8%, 39.6%, and 97.7%, respectively. These values were 96.3%, 37.9%, and 91.7% in 'PE likely' group (n=56), and 100%, 38.8%, and 100% in 'PE unlikely' group (n=84). Among 43 patients with D-dimer values of <230 ng/mL, only one patient was diagnosed with PE, who belonged to the 'PE likely' group. CONCLUSIONS: D-dimer test cannot be used as a stand-alone test to diagnose PE, but it can be helpful for exclusion of PE especially in 'PE unlikely' group according to Wells score.

Aspirin non-responsiveness in Korean subjects on dual anti-platelet treatment determined by two different platelet function assays.

Several techniques are available for measuring platelet function during aspirin therapy, but none is well standardized, and the reported incidence of aspirin non-responders varies widely, from 5 to 50%. We evaluated the optical platelet aggregation test and the Platelet Function Analyzer-100 test (PFA-100) for assessing aspirin responsiveness in patients receiving dual anti-platelet therapy, and we measured the incidence of non-responders to aspirin among Koreans. The study enrolled 88 participants including 51 patients on dual anti-platelet therapy, 31 controls, and 6 other volunteers. Optical platelet aggregation in response to 4 agonists and aggregation using the PFA-100 test were determined. In addition, medical records, including the results of platelet aggregation tests, were reviewed for 351 patients receiving aspirin therapy. The results showed good correlation between the PFA-100 test using a collagen/epinephrine cartridge (CEPI) and the optical platelet aggregation test using each agonist. The platelet aggregation test using arachidonic acid revealed marked suppression of aggregation (>98% inhibition) in patients taking aspirin; this value was highly correlated with the PFA-100 results using the CEPI cartridge. Seven of 351 Korean subjects (2.0%) receiving aspirin treatment were non-responsive to aspirin. This study shows that the optical platelet aggregation test using arachidonic acid gave an accurate assessment of the response to aspirin, and that results of the PFA-100 test using the CEPI cartridge correlated well with results of the optical platelet aggregation test.

[A case of therapy-related acute monocytic leukemia following low-dose of etoposide treatment for hemophagocytic lymphohistiocytosis].

We report a case of therapy-related acute myeloid leukemia after low-dosed topoisomerase II inhibitor (etoposide) treatment for hemophagocytic lymphohistiocytosis (HLH). A 62-yr-old female patient had previously been treated with a HLH-94 protocol containing a low-dose of etoposide (total dose of 300 mg/m2). Thirty-one months later, the patient was admitted to the hematology department with general weakness and upper respiratory infection symptoms. Peripheral blood smear and bone marrow study revealed acute monocytic leukemia. There was no evidence of myelodysplastic syndrome, and a cytogenetic study showed no chromosomal abnormalities.

[Establishment and management of medical genetic clinic based on genetic testing network.].

BACKGROUND: With the progress of the Human Genome Project, genetic testing has become widely available and useful for the confirmation and treatment planning of various conditions. Additionally, the need for genetic counseling and consultation service has been increasing. We tried to establish and manage a medical genetic clinic within the department of laboratory medicine by using a genetic testing network. METHODS: An Inter-laboratory network has been organized between Soonchunhyang University Bucheon Hospital and Samsung Medical Center since January, 2005. As clinical laboratory physicians, we provide medical services ranging from genetic counseling to genetic testing. In this study we surveyed the need and demand for genetic consultation services using a questionnaire. RESULTS: Of the 30 cases that were requested to receive a genetic consultation, 24 were referred to the genetic clinic during the last 11 months. Of these, 18 underwent genetic tests. The request for genetic consultation came mainly from neurology, obstetrics, and pediatrics departments and the distribution of requested disease entities was very heterogeneous. Operating processes became more settled compared to the early period and specific work fields were secured in the genetic consultation services. Over 80% of the respondents replied that a medical genetic clinic was important and that public relations campaign should be continued. CONCLUSIONS: Establishment of a medical genetic clinic by using a genetic testing network has led to important changes that the department of laboratory medicine is most suitable for genetic testing and medical genetic consultations and laboratory physicians should be concerned in that field. A medical genetic consultation system based on extensive genetic information and knowledge could enhance opportunities for cooperation in genetic research.