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The current guidelines for therapeutic drug monitoring (TDM) of vancomycin suggest a target 24-hour area under the curve (AUC 0-24 ) of 400 to 600 mg*h/L for serious methicillinresistant Staphylococcus aureus infections. In this study, the predictabilities of acute kidney injury (AKI) of various TDM target parameters, target levels, and sampling methods were evaluated in patients who underwent TDM from January 2020 to December 2020. The AUC 0-24 and trough values were calculated by both one- and two-point sampling methods, and were evaluated for the predictability of AKI. Among the AUC 0-24 cutoff comparisons, the threshold value of 500 mg*h/L in the two sampling methods was statistically significant (P = 0.042) when evaluated for the predictability of AKI. Analysis by an receiver operating characteristic curve estimated an AUC 0-24 cutoff value of 563.45 mg*h/L as a predictor of AKI, and was proposed as the upper limit of TDM target.
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Cerebrotendinous xanthomatosis (CTX) is a rare genetic disease caused by a deficiency of enzymes for the synthesis of bile acid, resulting in the accumulation of cholestanol with reduced chenodeoxycholic acid (CDCA) production and causing various symptoms such as chronic diarrhea in infancy, juvenile cataracts in childhood, tendon xanthomas in adolescence and young adulthood, and progressive neurologic dysfunction in adulthood. Because oral CDCA replacement therapy can effectively prevent disease progression, early diagnosis and treatment are critical in CTX. This study reports the case of CTX in a 10-year-old male who presented with Achilles tendon xanthoma and mild intellectual disability. Biochemical testing showed normal cholesterol and sitosterol levels but elevated cholestanol levels. Genetic testing showed compound heterozygous variants of CYP27A1, c.379C>T (p.Arg127Trp), and c.1214G>A (p.Arg405Gln), which confirmed the diagnosis of CTX. The patient had neither cataracts nor other focal neurologic deficits and showed no abnormalities on brain imaging. The patient received oral CDCA replacement therapy without any adverse effects; thereafter, the cholestanol level decreased and no disease progression was noted. The diagnostic possibility of CTX should be considered in patients with tendon xanthoma and normolipidemic conditions to prevent neurological deterioration.
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Background@#Accurate serum creatinine (Cr) concentration measurement is essential for evaluating kidney function. In 2011, the Korean Association of External Quality Assessment Service (KEQAS) launched an accuracy-based Cr proficiency testing (ABCr PT) survey. We analyzed long-term data of the KEQAS ABCr PT survey collected between 2011 and 2019 to assess recent trends in Cr assays in Korea. @*Methods@#The ABCr PT survey including three commutable fresh-frozen serum samples was performed twice a year. The target Cr concentration was assigned using isotope-dilution mass spectrometry. We analyzed data obtained from the participating laboratories, calculated the yearly bias, and evaluated bias trends for the major reagents and instruments. Outliers were excluded from all analysis. @*Results@#The mean percentage bias based on the total data of all participating laboratories was 10.8% in the 2011-A survey and 0.2% in 2019-B survey. Bias for the major reagents and instruments differed depending on the manufacturer. Enzymatic assays generally showed desirable bias ranging from –3.9% to 3.2% at all Cr concentrations and lower interlaboratory variability than non-enzymatic assays (enzymatic vs. non-enzymatic, 3.3%– 7.2% vs. 6.3%–9.1%). @*Conclusions@#Although the mean percentage bias of Cr assays tends to decrease over time, it is necessary to continuously strive to improve Cr assay accuracy, especially at low concentrations.
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Background@#Reference intervals defined for adults or children of other ethnicities cannot be applied in the evaluation of Korean pediatric patients. Pediatric reference intervals are difficult to establish because children are in their growing stage and their physiology changes continuously. We aimed to establish reference intervals for routine laboratory tests for Korean pediatric patients through retrospective multicenter data analysis. @*Methods@#Preoperative laboratory test results from 1,031 pediatric patients aged 0 month–18 years who underwent minor surgeries in four university hospitals were collected. Age- and sex-specific reference intervals for routine laboratory tests were defined based on the Clinical and Laboratory Standards Institute (CLSI) EP28-A3c guidelines. @*Results@#The pediatric reference intervals determined in this study were different from existing adult reference intervals and pediatric reference intervals for other ethnicities. Most tests required age-specific partitioning, and some of those required sex-specific partitioning for at least one age-partitioned subgroup. Erythrocyte sedimentation rate, monocyte percentage, basophil percentage, activated partial thromboplastin time, glucose, cholesterol, albumin, bilirubin, chloride, and C-reactive protein did not show any difference between age- or sex-partitioned subgroups. @*Conclusions@#We determined Korean pediatric reference intervals for hematology, coagulation, and chemistry tests by indirect sampling based on medical record data from multiple institutions. These reference intervals would be valuable for clinical evaluations in the Korean pediatric population.
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Cross-reactive carbohydrate determinants (CCDs) are simple carbohydrates linked to amino acid chains; they are found in pollens, vegetable foods, insect, and Hymenoptera venoms and are broadly cross-reactive with CCD-specific IgE antibodies. A man in his fifties was evaluated using a multiple allergen simultaneous test–immunoblot assay. On the PROTIA Allergy-Q 64 inhalant panel (ProteomeTech, Korea), reactions to 37 of 59 antigens were observed except mammalian antigens, and cross-reactivity owing to anti-CCD antibodies was suspected. After ProGlycAn CCD-blocker (ProGlycAn, Austria) treatment, the patient exhibited no response to CCD allergens, and the number of allergens showing positive reactions was reduced to 15. We further tested a total of 7 samples from patients who were suspected to have CCD-related cross-reactivity. For these 8 patients, the average number of positive reactions to allergens was reduced from 33 (range 24-36) to 8 (range 0-19) after CCD-blocker treatment. We concluded that CCD-blocker treatment in sample with anti-CCD antibodies can reduce the false positive reponse and provide more specific information about allergens.
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Fungi are a major cause of human infections with diverse clinical manifestations. The incidence of fungal infections has increased over time, particularly in patients who have risk factors such as neutropenia, immune suppression, an intravascular catheter, parenteral nutrition, a prosthetic device, and prior broad spectrum antibiotic therapy. Here, we present an unusual case of co-infection by 2 distinct fungi, Candida parapsilosis and Trichosporon asahii, isolated from a patient who did not have any known risk factors initially, except active pulmonary tuberculosis. Despite the negative conversion of sputum acid-fast bacilli (AFB) culture test after treatment, clinical symptoms were refractory to therapy. The patient developed symptoms suggesting septic shock, and 2 distinct colonies were isolated from a blood specimen, which were identified as C. parapsilosis and T. asahii by MALDI-TOF and rRNA sequencing. Fever and hypotension were relieved after anti-fungal agent injection, and pulmonary lesions identified by imaging also improved.
الموضوعات
Humans , Candida , Catheters , Coinfection , Fever , Fungemia , Fungi , Hypotension , Incidence , Neutropenia , Parenteral Nutrition , Risk Factors , Shock, Septic , Sputum , Trichosporon , Tuberculosis, Pulmonaryالملخص
The Clinical Mass Spectrometry Research Committee (CMSRC), in affiliation with the Korean Society of Clinical Chemistry (KSCC), conducted a questionnaire survey on opinions about the general status of clinical mass spectrometric analysis in Korea. As a result, we understand that this field has passed through the introductory stage and is settled as a field of clinical laboratory testing in Korea, with the number of new laboratories performing mass spectrometric analysis being low. In spite of the many difficulties in introducing and operating clinical mass spectrometric analysis, there is a strong interest in this field, and even though further expansion is expected, there are still many issues to be resolved. In the future, it will be necessary to make concrete and thorough efforts to further develop the laboratory tests using clinical mass spectrometric analysis in Korea, centering on the CMSRC affiliated with the KSCC.
الموضوعات
Chemistry, Clinical , Korea , Mass Spectrometryالملخص
BACKGROUND: Following discontinuation of the recombinant immunoblot assay (RIBA), the only available supplementary test for the detection of hepatitis C virus (HCV) is the nucleic acid amplification test (NAAT). However, the NAAT does not adequately detect past HCV. Consequently, it is hard to distinguish between past HCV infection and biological false positivity with an anti-HCV result alone. We assessed the diagnostic performance of two immunoassays: the ARCHITECT anti-HCV chemiluminescent microparticle immunoassay (CMIA; Abbott Diagnostics, Wiesbaden, Germany) and the Access HCV Ab PLUS chemiluminescent immunoassay (CIA; Bio-Rad, Marnes-la-Coquette, France). We also explored an optimized algorithm to determine the anti-HCV results. METHODS: We tested 126,919 patients and 44,556 individuals who underwent a medical checkup. RIBA and NAAT were conducted for samples that tested anti-HCV-positive using CMIA and CIA. We assessed the optimal signal-to-cutoff (S/CO) ratio in HCV-positive samples. RESULTS: In total, 1,035 blood samples tested anti-HCV-positive. Of these, RIBA was positive in 512, indeterminate in 160, and negative in 363 samples. One hundred sixty-five samples were NAAT-positive. Diagnostic sensitivity and positive predictive value (PPV) were 96.7% and 52.1%, respectively, for CMIA, and 94.7% and 72.3%, respectively, for CIA. The optimal S/CO ratio was 5.2 for CMIA and 2.6 for CIA at 95% PPV. In total, 286 samples tested positive in CMIA and 444 in CIA, while 443 samples tested positive in both assays. CONCLUSIONS: It is hard to determine anti-HCV positivity based on the S/CO ratio alone. However, this study elucidated the role of the S/CO ratio by using the NAAT and RIBA.
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Humans , Hepacivirus , Immunoassay , Nucleic Acid Amplification Techniquesالملخص
As part of the clinical chemistry programs of the Korean Association of External Quality Assessment Service, we organized trials to conduct external quality assessment of hemoglobin A1c (HbA1c) in 2016 and 2017. We delivered three commutable whole blood specimens for each trial. The overall response rates were 96.4% in 2016 and 98.4% and 99.6% in the first and second trials in 2017, respectively. Two types of reports were generated: a common report including the mean, standard deviation, coefficient of variation, median, minimum value, and maximum value according to manufacturer and instrument, as well as a summary report of the results from each participating laboratory, including a histogram for each specimen, Levey-Jennings chart for serial percent deviations, and table showing the target value, upper and lower limits, percent deviation, and grade. From 2016, the acceptance criterion was changed from ±8.0% to ±6.7%. The overall acceptable rates for the survey were 91.5%, 91.4%, 94.9%, and 89.0% for the first trial in 2016 through the second trial in 2017, respectively. The requisite continual improvement in the quality of HbA1c testing can be achieved through participation in similar accuracy-based proficiency testing programs.
الموضوعات
Chemistry, Clinical , Korea , Laboratory Proficiency Testing , Research Reportالملخص
BACKGROUND: The performance of the self-monitoring of blood glucose in patients with diabetes should be properly evaluated to ensure strict glycemic control. This study evaluated the self-testing Blood Glucose Monitoring System GlucoDr.S™ (All Medicus Co., Ltd., Korea). METHODS: This study recruited 120 patients. Use of the glucometer was evaluated according to ISO 15197:2013 guidelines. The YSI 2300 STAT PLUS Glucose Analyzer (YSI Life Sciences, USA) was used as the reference device. RESULTS: The standard deviation and coefficients of variation ranges for measurement repeatability and intermediate measurement precision conducted with 10 meters and 3 reagent lots on the same day were 2.7–3.2 mg/dL (0.99. The influence effect of hematocrit and the 24 interference agents was not significant, except for xylose. A system accuracy test was conducted with 100 subjects taking duplicate measurements from each of the 3 reagent lots. When glucose levels were 95% of the samples were within ±15 mg/dL and within ±15% of the average measured values of the reference measurement, respectively. In Consensus Error grid analysis, all results were distributed in zone A and B. The results of the user performance evaluation using 115 lay persons were also included in the acceptance range. CONCLUSION: The GlucoDr.S™ showed acceptable performance according to the ISO 15197:2013 guidelines and could be a clinically useful self-testing glucometer.
الموضوعات
Humans , Biological Science Disciplines , Blood Glucose , Consensus , Glucose , Hematocrit , Xyloseالملخص
BACKGROUND: Newborn screening of tyrosinemia type 1 is important for identifying infants at risk for developing this disease before life-threatening symptoms occur. It is difficult to differentiate between tyrosinemia type 1 and transient neonatal tyrosinemia (TNT) by analyzing tyrosine alone. Thus, succinylacetone must be analyzed. In this study, we measured succinylacetone in dried blood spot (DBS) by HPLC-tandem mass spectrometry (HPLC-MS/MS) and established cut-off values. METHODS: We used the hydrazine derivatization method to measure succinylacetone in 127 DBSs showing normal results in the newborn screening test and 93 DBSs showing increased tyrosine levels. We established cut-off values using the 99.9th percentile value or median+5 standard deviation value. RESULTS: Succinylacetone levels determined by our method were well-correlated with the results recommended by the Centers for Disease Control and Prevention for proficiency testing (r=0.9968). The succinylacetone levels in normal newborn DBSs were significantly lower than those in DBSs with high tyrosine levels (P < 0.001). The cut-off values were calculated to be 1.3 µM from the results of 127 normal DBS samples and 2.2 µM from 220 DBSs, including in 93 newborns with TNT. CONCLUSIONS: Measurement of succinylacetone in DBSs by HPLC-MS/MS is useful in individuals with increased tyrosine concentrations and can be used for rapid differential diagnosis of tyrosinemia when an appropriate cut-off value is established.
الموضوعات
Humans , Infant , Infant, Newborn , Diagnosis, Differential , Mass Screening , Mass Spectrometry , Methods , Tandem Mass Spectrometry , Trinitrotoluene , Tyrosine , Tyrosinemiasالملخص
BACKGROUND: Without standardization of medical laboratory's testing practices, there is an increase in false diagnoses when relying on test results. However, the effect of test standardization is difficult to assess numerically. This study's purpose is to quantify the effect of the standardization level of a laboratory on the prevalence of diabetes mellitus (DM) and impaired fasting glucose (IFG). METHODS: Laboratories were classified into three levels: ‘highly-standardized laboratory,’‘basically-standardized laboratory,’ and ‘non-standardized laboratory.’ Based on the results of Korean External Quality Assessment Scheme (KEQAS), the cutoff values for diagnosis of DM and IFG were recalculated, given false positive and false negative rates. RESULTS: The prevalence of DM and IFG in the population as a whole was estimated using the 2013 Korea National Health and Nutrition Examination Survey (KNHANES) database. When the prevalence of DM from KNHANES was 11.88% (95% confidence interval [CI], 10.59%–13.17%), the proportion with a systematic false error ranged from 10.91% (95% CI, 9.65%–12.17%) to 13.09% (95% CI, 11.74%–14.45%). The prevalence of IFG varied from 13.59% (95% CI, 12.25%–14.91%) to 40.49% (95% CI, 38.54%–42.43%), in contrast to 24.58% (95% CI, 22.85%–26.31%) of the reference value. The prevalence of DM and IFG tended to be over- and under-estimated more as the laboratory standardization level became lower, respectively. CONCLUSION: Our study proved that standardization of clinical laboratory tests is an important factor affecting the prevalence estimation of national disease statistics based on the simulation using KNHANES data.
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Diabetes Mellitus , Diagnosis , Diagnostic Tests, Routine , Fasting , Glucose , Korea , Nutrition Surveys , Prevalence , Reference Valuesالملخص
BACKGROUND: False-positive fecal immunochemical test (FIT) results in the National Cancer Screening Program (NCSP) for colorectal cancer may lead to unnecessary procedures, such as colonoscopies, increasing the medical costs. We estimated reductions in the cost of National Health Insurance according to the accreditation status of screening facilities participating in the NCSP for colorectal cancer. METHODS: We used data collected between 2007 and 2010 from NCSP and the Korea Central Cancer Registry to identify patients with colorectal cancer. We also ascertained the history of the accreditation of each facility by the Korean Laboratory Accreditation Program (KLAP). Budget impact was defined as a reduction in medical costs achieved when the false-positive rate of the non-accredited facilities decreased relative to that of the accredited facilities. RESULTS: A total of 3,285 screening facilities participated in the NCSP. Of these, 196 were accredited by the KLAP. The false-positive rate of the accredited facilities was 2.47%, and that of the non-accredited facilities was 6.83%. Medical costs were estimated to be reduced by approximately 19 million US dollars (USD), and the cost of detecting one case of colorectal cancer was estimated to decrease from 9,212 USD to 7,332 USD if the false-positive rate of non-accredited facilities were decreased to that of the accredited facilities. Clinics were estimated to have the largest associated cost reduction. CONCLUSIONS: Quality assurance in clinical laboratories could lower false-positive rates and prevent the use of unnecessary procedures, ensuring patient safety and increasing the cost-effectiveness of FIT screening in the NCSP for colorectal cancer.
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Humans , Accreditation , Budgets , Colonoscopy , Colorectal Neoplasms , Early Detection of Cancer , Korea , Mass Screening , National Health Programs , Patient Safety , Quality Improvement , Unnecessary Proceduresالملخص
BACKGROUND: Medical laboratories play a central role in health care. Many laboratories are taking a more focused and stringent approach to quality system management. In Korea, laboratory standardization efforts undertaken by the Korean Laboratory Accreditation Program (KLAP) and the Korean External Quality Assessment Scheme (KEQAS) may have facilitated an improvement in laboratory performance, but there are no fundamental studies demonstrating that laboratory standardization is effective. We analyzed the results of the KEQAS to identify significant differences between laboratories with or without KLAP and to determine the impact of laboratory standardization on the accuracy of diagnostic tests. METHODS: We analyzed KEQAS participant data on clinical chemistry tests such as albumin, ALT, AST, and glucose from 2010 to 2013. As a statistical parameter to assess performance bias between laboratories, we compared 4-yr variance index score (VIS) between the two groups with or without KLAP. RESULTS: Compared with the group without KLAP, the group with KLAP exhibited significantly lower geometric means of 4-yr VIS for all clinical chemistry tests (P<0.0001); this difference justified a high level of confidence in standardized services provided by accredited laboratories. Confidence intervals for the mean of each test in the two groups (accredited and non-accredited) did not overlap, suggesting that the means of the groups are significantly different. CONCLUSIONS: These results confirmed that practice standardization is strongly associated with the accuracy of test results. Our study emphasizes the necessity of establishing a system for standardization of diagnostic testing.
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Accreditation , Bias , Clinical Chemistry Tests , Delivery of Health Care , Diagnostic Tests, Routine , Glucose , Koreaالملخص
Metachromatic leukodystrophy is an inherited lysosomal storage disorder caused by the deficiency of arylsulfatase A activity. The patient in this study, a 5-yr-old girl, presented with progressive psychomotor regression. An MRI image of her brain showed bilateral symmetrical demyelination. The arylsulfatase A activity in her leukocytes was decreased to 8.0 nmol/hr/mg protein (reference range, 25-80 nmol/hr/mg protein). Mutation analysis of ARSA, using PCR and direct sequencing, showed two heterozygote pathogenic variations of c.449C>T (p.Pro150Leu) and c.640G>A (p.Ala214Thr). In summary, we report a Korean patient with an early juvenile form of metachromatic leukodystrophy, who was diagnosed based on her clinical symptoms as well as by using biochemical, radiological, and molecular genetic investigations.
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Female , Humans , Brain , Cerebroside-Sulfatase , Demyelinating Diseases , Heterozygote , Leukocytes , Leukodystrophy, Metachromatic , Magnetic Resonance Imaging , Molecular Biology , Polymerase Chain Reactionالملخص
BACKGROUND: The amino-terminal pro-brain natriuretic peptide (NT-proBNP) is a useful biomarker for the diagnosis of acute congestive heart failure. A point-of-care test (POCT) could rapidly detect the presence of NT-proBNP during emergencies. We evaluated the analytical performance of the new Samsung LABGEO PA CHF Test (Samsung Electronics, Korea). METHODS: Based on the guidelines of the Clinical and Laboratory Standards Institute (CLSI), we compared the precision, linearity, and method with those of the E170 (Roche Diagnostics, Switzerland). Matrix comparison between the NT-proBNP values in whole blood and plasma was also performed, and the reference interval was determined using residual samples from healthy adults selected based on the evaluation criteria. RESULTS: The Samsung LABGEO PA CHF Test provided results in approximately 18 min. The coefficient of variation (CV) of within-laboratory precision was below 6.8%. A desirable linearity was observed in the range of 0–10,000 pg/mL, with R²=0.99. The correlation with E170 was also excellent (N=108, r=0.96). NT-proBNP values in the whole blood were correlated with those in the plasma (N=36, r=0.99). The reference interval for the circulating NT-proBNP concentration was determined in 118 plasma samples from healthy subjects (26-75 yr of age). The 97.5th percentile was found to be 58.3 pg/mL. CONCLUSIONS: The Samsung LABGEO PA CHF Test demonstrated a good analytical performance. It could be a powerful tool as a POCT for clinical practice, particularly during emergencies.
الموضوعات
Adult , Humans , Diagnosis , Emergencies , Healthy Volunteers , Heart Failure , Methods , Plasma , Point-of-Care Systems , Point-of-Care Testingالملخص
BACKGROUND: Pyridoxal-5'-phosphate (P5P), a coenzyme of the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) reactions, is required to measure aminotransferase levels (IFCC method). However, a modified IFCC method that uses a reagent devoid of P5P is commonly used in laboratories in Korea. To determine the differences between the two methods, we compared aminotransferase levels measured by using the IFCC method and modified IFCC method. METHODS: Serum levels of AST and ALT, with and without P5P, were measured in 2,318 patients. Based on the allowable limits of performance set by the Royal College of Pathologists of Australasia (RCPA), differences between the two methods were analyzed under various conditions. RESULTS: Higher AST and ALT values were obtained by the IFCC method compared to modified IFCC method, showing significant differences between the two methods (AST, 5.8±14.2 IU/L; ALT, 2.8±6.9 IU/L) (P<0.001). Values exceeding RCPA criteria were more frequently observed in emergency orders (AST, 65.8%; ALT, 14.4%) than in routine orders (AST, 3.2%; ALT, 9.6%), as well as in inpatient wards (AST, 70.4%; ALT, 18.5%) compared to outpatient clinics (AST, 56.6%; ALT, 10.0%). However, the differences between the two methods were not significant among the disease groups, except for the acute myocardial infarction group. CONCLUSIONS: The method using reagents without P5P underestimated aminotransferase activity. The effect of P5P was more significant in patients with acute myocardial infarction, considered as P5P-deficient. In conclusion, the IFCC method with P5P should be applied for measuring AST and ALT serum levels.
الموضوعات
Humans , Alanine Transaminase , Ambulatory Care Facilities , Aspartate Aminotransferases , Australasia , Emergencies , Indicators and Reagents , Inpatients , Korea , Liver Function Tests , Methods , Myocardial Infarction , Pyridoxal Phosphateالملخص
BACKGROUND: Molecular techniques are fundamental for establishing an accurate diagnosis and therapeutic approach of glycogen storage diseases (GSDs). We aimed to evaluate SLC37A4 mutation spectrum in Korean GSD Ib patients. METHODS: Nine Korean patients from eight unrelated families with GSD Ib were included. SLC37A4 mutations were detected in all patients with direct sequencing using a PCR method and/or whole-exome sequencing. A comprehensive review of previously reported SLC37A4 mutations was also conducted. RESULTS: Nine different pathogenic SLC37A4 mutations were identified in the nine patients with GSD Ib. Among them, four novel mutations were identified: c.148G>A (pGly50Arg), c.320G>A (p.Trp107*), c.412T>C (p.Trp138Arg), and c.818G>A (p.Gly273Asp). The most common mutation type was missense mutations (66.7%, 6/9), followed by nonsense mutations (22.2%, 2/9) and small deletion mutations (11.1%, 1/9). The most common mutation identified in the Korean population was c.443C>T (p.Ala148Val), which comprised 39.9% (7/18) of all tested alleles. This mutation has not been reported in GSD Ib patients in other ethnic populations. CONCLUSIONS: This study expands knowledge of the SLC37A4 mutation spectrum in Korean patients with GSD Ib.