Clinical feature, GALC variant spectrum, and genotype-phenotype correlation in Korean Krabbe disease patients: Multicenter experience over 13 years.

Krabbe disease (KD) is an autosomal recessive neurodegenerative disorder caused by deficiency of the galactocerebrosidase (GALC) due to variants in the GALC gene. Here, we provide the first and the largest comprehensive analysis of clinical and genetic characteristics, and genotype-phenotype correlations of KD in Korean in comparison with other ethnic groups. From June 2010 to June 2023, 10 patients were diagnosed with KD through sequencing of GALC. Clinical features, and results of GALC sequencing, biochemical test, neuroimaging, and neurophysiologic test were obtained from medical records. An additional nine previously reported Korean KD patients were included for review. In Korean KD patients, the median age of onset was 2 years (3 months-34 years) and the most common phenotype was adult-onset (33%, 6/18) KD, followed by infantile KD (28%, 5/18). The most frequent variants were c.683_694delinsCTC (23%) and c.1901T>C (23%), while the 30-kb deletion was absent. Having two heterozygous pathogenic missense variants was associated with later-onset phenotype. Clinical features were similar to those of other ethnic groups. In Korean KD patients, the most common phenotype was the adult-onset type and the GALC variant spectrum was different from that of the Caucasian population. This study would further our understanding of KD.

Features which discriminate between tuberculosis and haematologic malignancy as the cause of pleural effusions with high adenosine deaminase.

BACKGROUND: Adenosine deaminase (ADA) is a useful biomarker for the diagnosis of tuberculous pleurisy (TBP). However, pleural effusions with high ADA can also be caused by other diseases, particularly hematologic malignant pleural effusion (hMPE). This study aimed to investigate the features that could differentiate TBP and hMPE in patients with pleural effusion ADA ≥ 40 IU/L. METHODS: This was a retrospective observational study of patients with pleural effusion ADA ≥ 40 IU/L, conducted at a Korean tertiary referral hospital with an intermediate tuberculosis burden between January 2010 and December 2017. Multivariable logistic regression analyses were performed to investigate the features associated with TBP and hMPE, respectively. RESULTS: Among 1134 patients with ADA ≥ 40 IU/L, 375 (33.1%) and 85 (7.5%) were diagnosed with TBP and hMPE, respectively. TBP and hMPE accounted for 59% (257/433) and 6% (27/433) in patients with ADA between 70 and 150 IU/L, respectively. However, in patients with ADA ≥ 150 IU/L, they accounted for 7% (9/123) and 19% (23/123), respectively. When ADA between 40 and 70 IU/L was the reference category, ADA between 70 and 150 IU/L was independently associated with TBP (adjusted odds ratio [aOR], 3.11; 95% confidence interval [CI], 1.95-4.95; P < 0.001). ADA ≥ 150 IU/L was negatively associated with TBP (aOR, 0.35; 95% CI, 0.14-0.90; P = 0.029) and positively associated with hMPE (aOR, 13.21; 95% CI, 5.67-30.79; P < 0.001). In addition, TBP was independently associated with lymphocytes ≥ 35% and a lactate dehydrogenase (LD)/ADA ratio < 18 in pleural effusion. hMPE was independently associated with pleural polymorphonuclear neutrophils < 50%, thrombocytopenia, and higher serum LD. A combination of lymphocytes ≥ 35%, LD/ADA < 18, and ADA < 150 IU/L demonstrated a sensitivity of 0.824 and specificity of 0.937 for predicting TBP. CONCLUSION: In patients with very high levels of pleural effusion ADA, hMPE should be considered. Several features in pleural effusion and serum may help to more effectively differentiate TBP from hMPE.

Evaluating the HYDRASHIFT 2/4 Daratumumab assay: a powerful approach to assess treatment response in multiple myeloma.

OBJECTIVES: This study evaluates the HYDRASHIFT assay's effectiveness in mitigating daratumumab interference on serum protein tests during multiple myeloma (MM) treatment, aiming to ensure an accurate assessment of treatment response. METHODS: We analyzed 113 serum samples from 68 MM patients undergoing daratumumab treatment, employing both standard IF and the HYDRASHIFT assay. The assay's precision was determined through intra-day and inter-day variability assessments, while its specificity was verified using serum samples devoid of daratumumab. Comparative analysis of IF results, before and after the application of the HYDRASHIFT assay, facilitated the categorization of treatment responses in alignment with the International Myeloma Working Group's response criteria. RESULTS: The precision underscored the assay's consistent repeatability and reproducibility, successfully eliminating interference of daratumumab-induced Gκ bands. Specificity assessments demonstrated the assay's capability to distinguish daratumumab from both isatuximab and naturally occurring M-proteins. Of the analyzed cases, 91 exhibited successful migration of daratumumab-induced Gκ bands, thereby enhancing the accuracy of treatment response classification. The remaining 22 cases did not show a visible migration complex, likely due to the low concentration of daratumumab in the serum. These findings underscore the assay's critical role in distinguishing daratumumab from endogenous M-protein, particularly in samples with a single Gκ band on standard IF, where daratumumab and endogenous M-protein had co-migrated. CONCLUSIONS: The HYDRASHIFT assay demonstrates high precision, specificity, and utility in the accurate monitoring of treatment responses in MM patients receiving daratumumab. This assay represents a significant advancement in overcoming the diagnostic challenges posed by daratumumab interference.

Effects of 20% albumin infusion therapy during liver transplantation on plasma neutrophil gelatinase-associated lipocalin level: A randomized controlled trial.

The risk of acute kidney injury (AKI) after liver transplantation was lower in patients with serum albumin levels ≥3.0 mg/dL during surgery. We tested whether intraoperative infusion of 20% albumin affects neutrophil gelatinase-associated lipocalin (NGAL) level, a reliable indicator of AKI. We randomly assigned 134 patients undergoing liver transplantation into albumin group (n=70, 20% albumin 200 mL) and the control group (n=66, crystalloid solution 200 mL). The 2 study fluids were infused at 100 mL/h from the start of the anhepatic phase. The primary outcome was plasma NGAL level at 1 hour after graft reperfusion. Albumin level at the start of graft reperfusion was significantly greater in albumin group than in the control group [2.9 (2.4-3.3) g/dL vs. 2.3 (2.0-2.7) g/dL, p <0.001]. The NGAL level at 1 hour after graft reperfusion was not significantly different between the 2 groups [100.2 (66.7-138.8) ng/mL vs. 92.9 (70.8-120.6) ng/mL, p =0.46], and the AKI risk was not either (63.9% vs. 67.8%, adjusted p =0.73). There were no significant differences between the 2 groups regarding hospital readmission within 30 days/90 days after transplantation (32.6% vs. 41.5%, adjusted p =0.19 and 55.0% vs. 55.7%, adjusted p =0.87). Graft survival probability at 30 days/90 days/1 year after transplantation was 90.0%/84.3%/78.6% in albumin group and 97.0%/90.9%/89.4% in the control group [HR=1.6 (0.6-4.0), adjusted p =0.31]. In conclusion, intraoperative infusion of 20% albumin 200 mL increased the albumin level but failed to maintain serum albumin ≥3.0 mg/dL during surgery. The hypertonic albumin therapy did not significantly affect plasma NGAL level and clinical outcomes including AKI.

A novel splicing variant in GALNS in mucopolysaccharidosis IVA and the necessity of re-evaluating primer sequences.

Mucopolysaccharidosis type IVA (MPS IVA; Morquio syndrome type A) is an autosomal recessive disorder caused by defects in the lysosomal hydrolase N-acetylgalactosamine-6-sulfatase (GALNS) gene, leading to progressive systemic skeletal dysplasia. Early diagnosis and early intervention with enzyme replacement therapy are crucial for improving outcomes in these patients. However, a relatively high number of patients are genetically undiagnosed due to high allelic heterogeneity and the absence of robust functional evidence for most variants of the GALNS gene. Herein, we report a novel intronic variant identified with RNA analysis and an allele dropout (ADO) event caused by a common benign variant in the primer-binding site in a Korean boy with MPS IVA. A 28-month-old boy presented with pectus carinatum, kyphoscoliosis, and joint hypermobility with multiple skeletal dysplasia involving the vertebrae and hip joint. Total urinary glycosaminoglycans were elevated with a predominant keratan sulfate fraction, and GALNS (EC 3.1.6.4) activity was significantly decreased in leukocytes. Sanger sequencing was performed; however, only one heterozygous intronic variant with uncertain clinical significance, c.566+3A > T (p.(?)), was identified. As the patient exhibited clinical and biochemical features of MPS IVA, we conducted whole genome sequencing (WGS) of the patient and his family to clarify the molecular diagnosis. WGS revealed a compound heterozygous genotype, c.1019G > A (p.(Gly340Asp)) and c.566+3A > T (p.(?)), in the GALNS gene. On mRNA sequencing, c.566+3A > T, was confirmed to cause exon 5 skipping and a premature stop codon. With subsequent investigation, we discovered that the variant, c.1019G > A, was undetected on initial sequencing because of ADO due to a common benign variant (rs3859024:G > C) at the primer annealing location. We present a novel intronic variant with a splicing defect in the GALNS gene and suggest that clinicians review primer sequences in cases not diagnosed on Sanger sequencing before progressing to diagnostic steps such as WGS.

Pharmacokinetic/pharmacodynamic parameters of vancomycin for predicting clinical outcome of enterococcal bacteremia.

PURPOSE: To find pharmacokinetic/pharmacodynamic parameters of vancomycin associated with the optimal outcome of severe infection due to Enterococcus species. METHODS: We retrospectively reviewed enterococcal bacteremia cases treated with vancomycin from January 2015 to December 2020. The primary outcome was 30-day mortality. We calculated cutoff values of the ratio of vancomycin area under the concentration-time curve over 24 h to the minimum inhibitory concentration (AUC24/MIC) and trough concentration (Ctrough) during the initial 72 h of treatment. The optimal cutoff value was determined using the Youden index. Binary variables created based on these cutoffs were further assessed using multivariable analysis. RESULTS: A total of 65 patients were included. The majority (87.7%) had solid or hematologic malignancies. Thirty-day mortality and nephrotoxicity occurred in nine (13.4%) and 14 (21.5%) patients, respectively. Both vancomycin AUC24/MIC and Ctrough showed fair performance in predicting 30-day mortality (AUC of receiver-operator curve for AUC24/MIC, 0.712; 95% confidence interval [CI] 0.539-0.886; AUC for Ctrough, 0.760; 95% CI 0.627-0.892; pairwise AUC comparison: p = 0.570). Ctrough ≥ 13.94 µg/mL, but not AUC24/MIC ≥ 504, had a significant association with 30-day mortality after adjusting for confounders (odds ratio, 8.40; 95% CI 1.60-86.62; p = 0.010). CONCLUSION: Mean Ctrough ≥ 13.94 µg/mL during the initial 72 h was associated with higher 30-day mortality in enterococcal bacteremia. Further studies are warranted to elucidate optimal pharmacokinetic targets for enterococcal bacteremia.

Performance evaluation of the i-Smart 300E cartridge for point-of-care electrolyte measurement in serum and plasma.

BACKGROUND: Electrolytes are measured regularly in a variety of clinical settings because electrolyte imbalance can be life-threatening. Although arterial blood-gas analysis reports electrolyte levels, the result often is discrepant with results from serum and plasma samples. Since prompt and accurate measurement of serum electrolyte levels could allow early treatment, point-of-care (POC) electrolyte analyzers would be beneficial. We evaluated a POC electrolyte analyzer cartridge based on the Clinical and Laboratory Standard Institute (CLSI) guidelines. METHODS: Precision and linearity were assessed according to the CLSI EP05-A3 and EP06-A guidelines, respectively. A comparison study was conducted with both serum and plasma samples according to the CLSI EP09-A3. For serum, results from the i-Smart 300E analyzer were compared with results from the Nova 8 and i-Smart 30 analyzers. For plasma, results were compared among the i-Smart 300E, Nova 8, i-Smart 30, and Cobas c702 analyzers. RESULTS: Coefficients of variation in the precision analysis were all less than 5%. Linearity assessment demonstrated a coefficient of determination between 0.999 and 1.000 for all analytes. The comparison study showed a high Pearson's correlation coefficient greater than 0.9 for all analytes, instruments, and specimens. CONCLUSIONS: The i-Smart 300E demonstrated good analytical performance. Its use could be beneficial in terms of both efficiency and clinical outcome in point-of-care testing (POCT) for electrolyte levels from serum and plasma samples.

Prognostic implication of elevated cardiac troponin I in patients visiting emergency department without diagnosis of coronary artery disease.

OBJECTIVES: Elevated cardiac troponin is not uncommon in patients visiting emergency department (ED) even without coronary artery disease, but its prognostic implication is not well understood in such patients. METHODS: In this retrospective single-center registry, we investigated clinical outcome of patients visiting ED without documented coronary artery disease. Patients were categorized according to the maximal value of Siemens ADVIA Centaur TnI-Ultra assay (TnI) within 24 h after visit. Primary endpoint was 180-day all-cause death that included cardiac and non-cardiac death. RESULTS: A total of 35,205 patients with median age 61 years and male gender 54.7% were included. Below the lowest level of detection (LOD) (≤0.006 ng/mL), between LOD and assay-specific <99th percentile (0.007-0.039 ng/mL), below median of ≥99th percentile (0.040-0.149 ng/mL), and above median of ≥99th percentile (≥0.150 ng/mL) TnI were found in 18,502 (52.6%), 11,338 (32.2%), 3,029 (8.6%), and 2,336 (6.6%) patients. In the 180-day follow-up period, 4,341 (12.3%) all-cause death including 694 (2.0%) cardiovascular death and 3,647 (10.4%) non-cardiovascular death developed. The risks of all-cause, cardiovascular, and non-cardiovascular death increased across higher TnI strata (hazard ratio [HR]=1.3 to 2.4; 2.0 to 9.3; 1.3 to 1.7; p<0.001, all). Analyses of multivariate models showed consistent results. CONCLUSIONS: In patients visiting ED, elevated TnI was associated with higher risk of 180-day cardiovascular and non-cardiovascular death. Patients with elevated TnI may need additional evaluation or careful follow-up even without primary diagnosis of coronary artery disease.

Analytical and clinical performance of the Advansure i3 procalcitonin assay.

Procalcitonin (PCT) is a clinically useful biomarker for early diagnosis and subsequent management of sepsis. We evaluated the analytical performance of a new automated chemiluminescent immunoanalyzer-based procalcitonin assay, AdvanSure i3 PCT assay (LG Life Sciences, Korea) on an AdvanSure i3 (LG Life Sciences) and compared it to the Elecsys BRAHMS PCT assay (Roche, Switzerland) on a Cobas e801 (Roche). Analytical performance was performed for the precision, linearity, and method comparison with the Elecsys BRAHMS PCT assay by Clinical and Laboratory Standards Institute guidelines. Clinical evaluations were conducted using 87 residual samples from admitted patients with suspected infection. The patients were classified based on Sepsis-3 classification. The AdvanSure i3 PCT assay exhibited a CV <5.5% for between-run precision and <6.5% for within-laboratory precision. The assay was linear up to 80.32 µg/L (r = 0.990). Statistical analysis showed that the two assays yielded a good correlation (r = 0.996), with a weighted kappa value of 0.94. Median plasma PCT level was significantly different between the non-sepsis and sepsis groups (p < .001) and the non-sepsis and septic shock groups (p < .0018). The AdvanSure i3 PCT assay showed good analytical performance and correlation with the Elecsys BRAHMS PCT assay for the sepsis patients. This new assay can be used as a diagnostic early marker of sepsis in clinical laboratories.

Therapeutic Drug Level Monitoring of Teicoplanin in Korean Pediatric Patients with Normal versus Impaired Renal Function.

BACKGROUND: Teicoplanin is used to treat serious gram-positive infections. Optimal teicoplanin trough levels are considered to be ≥ 10 µg/mL. Despite its wide use in various clinical settings, data on teicoplanin trough level in pediatric patients are limited. Therefore, the aim of this study was to investigate the therapeutic drug level monitoring of teicoplanin in Korean pediatric patients, including those with impaired renal function. METHODS: A retrospective study was performed in pediatric patients (age ≤ 18 years old) who received teicoplanin from September 2014 to April 2018. The regimen included a loading dose of 10 mg/kg/dose at 12 hours' interval three times in a row, and a maintenance dose of 10 mg/kg/dose commenced at 24 hours of interval after the loading dose, with a maximum of 400 mg/dose, respectively. The first therapeutic drug levels were measured. Distribution and characteristics of trough levels in patients with decreased renal function and those with bacteremia were also assessed. RESULTS: A total of 187 trough levels were collected from 143 patients. Hematologic and oncologic diseases were the most common underlying diseases (83.2%, n = 119). One hundred eighty trough levels were first measured, and their median value was 16.2 µg/mL (range, 2.3-100 µg/mL) and the median interval between initial teicoplanin injection and 1st trough level was 96.5 hours (range 47.6-179.3 hours). Lower steady-state levels were observed in younger age group (median, 13.5 vs. 18.0 µg/mL, P = 0.038). Median trough levels were higher in patients with decreased renal functions (P < 0.001). In addition, among eight with gram-positive bacteremia, seven of them had a favorable outcome. CONCLUSION: This study provides additive information on trough level monitoring of teicoplanin in children with impaired renal function and treatment effect in patients with gram-positive bacteremia. Careful monitoring for steady state trough levels of teicoplanin is warranted.

Creatinine- and cystatin C-based estimated glomerular filtration rate slopes for the prediction of kidney outcome: a comparative retrospective study.

BACKGROUND: Many studies have evaluated the usefulness of creatinine- (eGFRcr) and cystatin C-based estimated glomerular filtration rate (eGFRcys) at specific time points in predicting renal outcome. This study compared the performance of both eGFR changing slopes in identifying patients at high risk of end-stage renal disease (ESRD). METHODS: From 2012 to 2017, patients with more than three simultaneous measurements of serum creatinine and cystatin C for 1 year were identified. Rapid progression was defined as eGFR slope < - 5 mL/min/1.73 m2/year. The primary outcome was progression to ESRD. RESULTS: Overall, 1323 patients were included. The baseline eGFRcr and eGFRcys were 39 (27-48) and 38 (27-50) mL/min/1.73 m2, respectively. Over 2.9 years (range, 2.0-3.8 years) of follow-up, 134 subjects (10%) progressed to ESRD. Both the eGFRcr and eGFRcys slopes were associated with a higher risk of ESRD, independently of baseline eGFR (hazard ratio [HR] = 0.986 [0.982-0.991] and HR = 0.988 [0.983-0.993], respectively; all p <  0.001). The creatinine- and cystatin C-based rapid progressions were associated with increased risk of ESRD (HR = 2.22 [1.57-3.13], HR = 2.03 [1.44-2.86], respectively; all p <  0.001). In the subgroup analyses, the rapid progression group, defined on the basis of creatinine levels (n = 503), showed no association between the eGFRcys slope and ESRD risk (p = 0.31), whereas the eGFRcr slope contributed to further discriminating higher ESRD risk in the subjects with rapid progression based on eGFRcys slopes (n = 463; p = 0.003). CONCLUSIONS: Both eGFR slopes were associated with future ESRD risk. The eGFRcr slope was comparable with the eGFRcys slope in predicting kidney outcome.

Performance evaluation of serum PIVKA-II measurement using HISCL-5000 and a method comparison of HISCL-5000, LUMIPULSE G1200, and ARCHITECT i2000.

BACKGROUND: Protein induced by vitamin K antagonist-II (PIVKA-II), in addition to alpha-fetoprotein, is a useful tumor marker for diagnosis of hepatocellular carcinoma (HCC). We evaluated the analytical performance of the HISCL-5000 analyzer (Sysmex Corporation) in the measurement of serum PIVKA-II. METHODS: We evaluated the precision and linearity of PIVKA-II assays using the HISCL-5000 analyzer. Methods using HISCL-5000, LUMIPULSE G1200 (Fujirebio Diagnostics), and ARCHITECT i2000 (Abbott Diagnostics) were compared according to the guidelines of the Clinical and Laboratory Standards Institute. A total of 501 subjects (median age 59 years, age range 24-90 years) were enrolled. Among them, 335 were HCC patients, 46 were patients with non-HCC liver disease, and 120 were healthy individuals. Non-HCC liver disease included liver cirrhosis, chronic hepatitis, HBV or HCV carrier, hepatic adenoma, and intrahepatic cholangiocarcinoma. RESULTS: Repeatability (%CV) in low- and high-level controls and pooled serum was 2.81%-10.30%, and within-laboratory precision was 4.24%-8.86%. In a linearity test, the coefficient of determination (R2 ) was 0.9957, ranging from 11 to 69 897 mAU/mL. In comparison, the coefficient of correlation (r) was 0.9561-0.9644, agreement was 93.4%-97.6%, and the κ value was 0.855-0.945 among the three analyzers. About 99.2% of healthy individuals and 84.8% of non-HCC liver disease patients were below the cutoff value (40 mAU/mL) on HISCL-5000. CONCLUSIONS: A PIVKA-II assay using HISCL-5000 showed acceptable analytical performance including precision, linearity, and method comparison. This indicates that HISCL-5000 can be potentially helpful in clinical laboratories.

Performance evaluation of serum IgG subclass quantification using a SPAPLUS turbidimetric analyzer and comparison with the BNII nephelometer.

IgG consists of four subclasses: IgG1, IgG2, IgG3, and IgG4. Changes in the serum concentration of each subclass reflect different clinical situations, and quantification of each subclass is important to assess patients' clinical states. Herein, we evaluated the analytical performance of the SPAPLUS turbidimetric analyzer (The Binding Site, Birmingham, UK) for IgG subclass. Precision, linearity, comparison with the BNII system (Siemens Healthineers, Erlangen, Germany), and reference interval were assessed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The repeatability and within-laboratory precision were within 5% for all IgG subclasses. The coefficient of determination (R2) was higher than 0.99 for the analytical measurement range in all IgG subclasses. Comparison between SPAPLUS and BNII revealed significant differences in IgG1, IgG3, and IgG4 (p < .0001). IgG1 and IgG4 values were lower in SPAPLUS than BNII. On the other hand, IgG3 values were higher in SPAPLUS than BNII. The SPAPLUS turbidimetric analyzer exhibited good analytical performance for quantification of four IgG subclasses. Because of the differences between SPAPLUS and BNII, follow-up test for disease monitoring should be performed with same instrument.

Non-alcoholic fatty liver disease and progression of coronary artery calcium score: a retrospective cohort study.

BACKGROUND AND AIM: Non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation of the metabolic syndrome, was associated with subclinical atherosclerosis in many cross-sectional studies, but the prospective association between NAFLD and the progression of atherosclerosis has not been evaluated. This study was conducted to evaluate the association between NAFLD and the progression of coronary atherosclerosis. METHODS: This retrospective cohort study included 4731 adult men and women with no history of cardiovascular disease (CVD), liver disease or cancer at baseline who participated in a repeated regular health screening examination between 2004 and 2013. Fatty liver was diagnosed by ultrasound based on standard criteria, including parenchymal brightness, liver-to-kidney contrast, deep beam attenuation and bright vessel walls. Progression of coronary artery calcium (CAC) scores was measured using multidetector CT scanners. RESULTS: The average duration of follow-up was 3.9 years. During follow-up, the annual rate of CAC progression in participants with and without NAFLD were 22% (95% CI 20% to 23%) and 17% (16% to 18%), respectively (p<0.001). The multivariable ratio of progression rates comparing participants with NAFLD with those without NAFLD was 1.04 (1.02 to 1.05; p<0.001). The association between NAFLD and CAC progression was similar in most subgroups analysed, including in participants with CAC 0 and in those with CAC >0 at baseline. CONCLUSIONS: In this large cohort study of adult men and women with no history of CVD, NAFLD was significantly associated with the development of CAC independent of cardiovascular and metabolic risk factors. NAFLD may play a pathophysiological role in atherosclerosis development and may be useful to identify subjects with a higher risk of subclinical disease progression.

Report of 5 novel mutations of the α-L-iduronidase gene and comparison of Korean mutations in relation with those of Japan or China in patients with mucopolysaccharidosis I.

BACKGROUND: Mucopolysaccharidosis I (MPS I) is an autosomal recessive lysosomal storage disorder caused by a lack of the lysosomal enzyme α-L-iduronidase (IDUA). To date, more than 200 IDUA mutations have been reported. However, only a few types of mutations are recurrent and the frequencies of mutations differ from country to country. METHODS: We performed the IDUA mutation analysis in seven patients who were biochemically diagnosed with MPS I in the Department of Pediatrics, Samsung Medical Center, from 2009 to 2014. Here, we describe the results of the IDUA mutation analysis in seven patients with MPS I and the IDUA mutational spectrum in Korean patients with MPS I, including previous data. RESULTS: The IDUA mutations were found in all 14 alleles of 7 patients, and 11 kinds of IDUA mutations were identified. The detected mutations were five missense mutations (p.A79V, p.L346R, p.T388K, p.P496R, and p.C577Y), two nonsense mutations (p.Y618* and p.R628*), two deletions (c.683delC and c.1591delC), one splice site mutation (c.972+1G>A), and one duplication (c.613_617dup). Among these, p.T388K, p.C577Y, c.683delC, c.1591delC, and c.972+1G>A were novel mutations that have not previously been reported. After taking everything into consideration, including IDUA mutation analysis of the previously reported 10 unrelated Korean patients with MPS I, p.L346R and c.704ins5 were most commonly found in Korean patients with MPS I. However, p.W402* and p.Q70*, which have mainly been found in Caucasian patients, were not found. CONCLUSION: As a result, p.L346R and c.704ins5, which were the most common in Korea, which is geographically situated midway between China and Japan, were some of the most common mutations in China and Japan, respectively. These results are especially worthy of notice.

PHKA2 mutation spectrum in Korean patients with glycogen storage disease type IX: prevalence of deletion mutations.

BACKGROUND: Molecular diagnosis of glycogen storage diseases (GSDs) is important to enable accurate diagnoses and make appropriate therapeutic plans. The aim of this study was to evaluate the PHKA2 mutation spectrum in Korean patients with GSD type IX. METHODS: Thirteen Korean patients were tested for PHKA2 mutations using direct sequencing and a multiplex polymerase chain reaction method. A comprehensive review of the literature on previously reported PHKA2 mutations in other ethnic populations was conducted for comparison. RESULTS: Among 13 patients tested, six unrelated male patients with GSD IX aged 2 to 6 years at the first diagnostic work-up for hepatomegaly with elevated aspartate transaminase (AST) and alanine transaminase (ALT) were found to have PHKA2 mutations. These patients had different PHKA2 mutations: five were known mutations (c.537 + 5G > A, c.884G > A [p.Arg295His], c.3210_3212delGAG [p.Arg1072del], exon 8 deletion, and exons 27-33 deletion) and one was a novel mutation (exons 18-33 deletion). Notably, the most common type of mutation was gross deletion, in contrast to other ethnic populations in which the most common mutation type was sequence variant. CONCLUSIONS: This study expands our knowledge of the PHKA2 mutation spectrum of GSD IX. Considering the PHKA2 mutation spectrum in Korean patients with GSD IX, molecular diagnostic methods for deletions should be conducted in conjunction with direct sequence analysis to enable accurate molecular diagnosis of this disease in the Korean population.

Evaluation of alpha-fetoprotein as a screening marker for hepatocellular carcinoma in hepatitis prevalent areas.

The objective of this study was to establish modified cutoff values of serum alpha-fetoprotein (AFP) according to hepatitis status. While AFP is used as a serum marker in the diagnosis or monitoring of hepatocellular carcinoma (HCC), its use as a screening method to the general population is controversial. We evaluated its screening performance in a hepatitis prevalent East Asian population, and suggest different cutoff values according to the individual's hepatitis status. We evaluated the performance of AFP as a screening test in 48,123 consecutive Koreans during the period from March, 2012 to August, 2013 who underwent routine health checks at a single institution. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with fixed cutoff and with modified cutoffs according the individual's hepatitis status. A total of 24 out of 48,123 subject (0.05%) were newly diagnosed with HCC after screening. Among the 1,874 subject with positive hepatitis B virus surface antigen (HBsAg), 17 (0.91%) developed HCC, compared with two out of 393 (0.51%) individuals with hepatitis C virus antibody (anti-HCV). Five out of 45,855 (0.01%) subject with neither HBsAg nor anti-HCV developed HCC. Compared to the performance of a fixed cutoff, specificity, PPV, and NPV improved without sacrificing sensitivity when applying modified cutoff. In conclusion, our findings suggest that AFP with modified cutoffs according to the individual's hepatitis status might be a useful screening marker for HCC in hepatitis prevalent areas.

Novel GALT variations and mutation spectrum in the Korean population with decreased galactose-1-phosphate uridyltransferase activity.

BACKGROUND: Classic galactosemia (OMIM #230400) is an autosomal recessive metabolic disorder caused by a deficiency of the galactose-1-phosphate uridyltransferase (GALT, EC2.7.7.12) protein due to mutations in the GALT gene. The aim of this study was to provide a comprehensive and updated mutation spectrum of GALT in a Korean population. METHODS: Thirteen unrelated patients screened positive for galactosemia in a newborn screening program were included in this study. They showed a reduced GALT enzyme activity in red blood cells. Direct sequencing of the GALT gene and in silico analyses were done to evaluate the impact of novel variations upon GALT enzyme activity. We also reviewed previous reports for GALT mutations in Koreans. RESULTS: We identified six novel likely pathogenic variations including three missense (p.Ala101Asp, p.Tyr165His, and p.Pro257Thr), one small deletion/insertion [c.826_827delinsAA (p.Ala276Asn)], one frameshift (p.Asn96Serfs*5), and one splicing (c.378-1G > C) likely pathogenic variations. The most frequent variation was the Duarte variant (c.940A > G, 35.3%), followed by c.507G > C (p.Gln169His, 9.6%), among 34 Korean patients. Other mutations were widely scattered. None of the eight common mutations used for targeted mutation analysis in Western countries including p.Gln188Arg, p.Ser135Leu, p.Lys285Asn, p.Leu195Pro, p.Tyr209Cys, p.Phe171Ser, c.253-2A > G, and a 5 kb deletion, had been found in Koreans until this study. CONCLUSIONS: Considering the mutation spectrum in Koreans, direct sequence analysis of entire GALT exons is recommended for accurate diagnosis. The mutations responsible for GALT deficiency in the Korean population were clearly different from those of other populations.

Ultra-performance liquid chromatography/tandem mass spectrometry for determination of sulfatides in dried blood spots from patients with metachromatic leukodystrophy.

RATIONALE: Metachromatic leukodystrophy (MLD) is a genetic autosomal recessive disease caused by a deficiency in arylsulfatase A. Accumulated sulfatides can be detected in the urine and detection of sulfatiduria is a useful test for diagnosis and monitoring. To our knowledge, no studies have explored the accumulation of sulfatides in dried blood spots (DBSs). We developed an ultra-performance liquid chromatography/tandem mass spectrometry (UPLC/MS/MS) method for measuring sulfatides in DBSs from patients with MLD. METHODS: DBSs were eluted with internal standard. After mixing and centrifugation, the organic layer was transferred to a 96-well microplate and dried, then resuspended in methanol/propanol solution. Samples were analyzed on an UPLC system. Total running time was 4 min. Quantification was achieved by multiple reaction monitoring using a tandem mass spectrometer. We evaluated the precision, linearity, and ion suppression of the method and analyzed sulfatide concentrations in DBS specimens from MLD patients (n = 9), pseudodeficiency (PD) patient (n = 1), obligate heterozygotes (OH) (n = 2) and normal controls (n = 124). RESULTS: In negative-ion mode, sulfatides species subjected to collision-induced dissociation readily fragment to produce an intense ion at m/z 96.8 (HSO4(-)). The precisions of low and high concentration controls ranged from 5.4 to 19.9%. The sulfatides produced linear responses. Molecular species of sulfatides were barely detected in DBSs from normal individuals and the PD-OH group [mean (range), 0.07 (<0.05-0.34) and 0.13 (<0.05-0.22) µg/mL, respectively]. In contrast, the DBSs from MLD patients showed a marked increase in several molecular species of sulfatide [mean (range), 2.02 (1.18-3.89) µg/mL]. CONCLUSIONS: Simultaneous detection for sulfatides using UPLC/MS/MS can be successfully applied to DBS analysis. This method provides a fast and effective screening and monitoring tool for the diagnosis and treatment of MLD.

Steroid profiling for congenital adrenal hyperplasia by tandem mass spectrometry as a second-tier test reduces follow-up burdens in a tertiary care hospital: a retrospective and prospective evaluation.

BACKGROUND: Newborn screening for congenital adrenal hyperplasia (CAH) based on measuring 17-hydroxyprogesterone (17-OHP) by immunoassay generates a number of false-positive results, especially in preterm neonates. We applied steroid profiling by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a second-tier test in newborns with positive CAH screening and evaluated its clinical utility in a tertiary care hospital setting. METHODS: By performing a 4-year retrospective data review, we were able to test 121 dried blood spots from newborns with positive CAH screening for 17-OHP, androstenedione and cortisol levels by LC-MS/MS. We prospectively evaluated the clinical utility of steroid profiling after the implementation of steroid profiling as a second-tier test in our routine clinical practice. During the 2-year prospective study period, 104 cases with positive initial screening by FIA were tested by LC-MS/MS. Clinical and laboratory follow-up were performed for at least 6 months. RESULTS: The preterm neonates accounted for 50.7% (76/150) and 70.4% (88/125) of screening-positive cases in retrospective and prospective cohorts, respectively. By applying steroid profiling as a second-tier test for positive CAH screening, we eliminated all false-positive results and decreased the median follow-up time from 75 to 8 days. CONCLUSIONS: Our data showed that steroid profiling reduced the burden of follow-up exams by improving the positive predictive value of the CAH screening program. The use of steroid profiling as a second-tier test for positive CAH screening will improve clinical practice particularly in a tertiary care hospital setting where positive CAH screening from preterm neonates is frequently encountered.