Status of FLT3-ITD Analysis in Korea (2021)

배경: FLT3-internal tandem duplication (ITD)는 급성골수백혈병에서 중요한 예후 인자이며 FLT3 억제제의 표적 돌연변이로, 치료 후 미세잔존질환 모니터링에 이용되기도 한다. 본 연구에서는 국내 FLT3-ITD 검사의 실태조사를 위한 온라인 설문조사를 시행하였다. 방법: 대학병원 및 3차 의료기관 검사실 책임자에게 전자 메일을 통한 설문을 시행하였다. 설문 문항은 FLT3-ITD 검사에 대한 기관별 검사 이용 및 수행 현황, 검출한계 및 정량한계 검증, 내·외부 정도관리 시행 여부, 결과보고 및 FLT3-ITD 정량 검사에 대한 의견을 포함하였다. 결과: 24개 기관의 회신을 받았다. 설문조사 결과 대부분의 기관에서 FLT3-ITD 확인 및 대립유전자 비율 확인을 위하여 절편분석법을 이용하고 있었다. 대부분의 기관에서 진단 및 경과 관찰 시 FLT3-ITD 대립유전자 비율을 보고하고 있었다. FLT3-ITD 검사에 대한 검사실 자체 검출한계 검증 및 내부정도관리를 시행하고 있었으며 국내외 외부정도관리 프로그램에 참여하고 있었다. 결론: 설문 참여 기관들은 FLT3-ITD 대립유전자 비율의 정확성 및 신뢰도를 높일 수 있는 검사 수행능 검증 및 외부정도관리 필요성에 공감하였다. 본 설문조사 결과가 향후 FLT3-ITD 검사의 표준안 설정에 바탕이 되어 궁극적으로 환자 진료에 긍정적 영향을 미치게 되길 기대한다.ope

Altered Gut Microbiota and Shift in Bacteroidetes between Young Obese and Normal-Weight Korean Children: A Cross-Sectional Observational Study

Emerging data suggest that the gut microbiome is related to the pathophysiology of obesity. This study is aimed at characterizing the gut microbiota composition between obese and normal-weight Korean children aged 5-13. We collected fecal samples from 22 obese and 24 normal-weight children and performed 16S rRNA gene sequencing using the Illumina MiSeq platform. The relative abundance of the phylum Bacteroidetes was lower in the obese group than in the normal-weight group and showed a significant negative correlation with BMI z-score. Linear discriminative analysis (LDA) coupled with effect size measurement (LEfSe) analysis also revealed that the Bacteroidetes population drove the divergence between the groups. There was no difference in alpha diversity, but beta diversity was significantly different between the normal-weight and obese groups. The gut microbial community was linked to BMI z-score; blood biomarkers associated with inflammation and metabolic syndrome; and dietary intakes of niacin, sodium, vitamin B6, and fat. The gut microbiota of the obese group showed more clustering of genera than that of the normal-weight group. Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) analysis revealed that the functions related to carbohydrate and lipid metabolism in the microbiota were more enriched in the normal-weight group than in the obese group. Our data may contribute to the understanding of the gut microbial structure of young Korean children in relation to obesity. These findings suggest that Bacteroidetes may be a potential therapeutic target in pediatric obesity.ope

First Korean Case of Pediatric Acute Megakaryoblastic Leukemia with CBFA2T3::GLIS2 Fusion

Acute megakaryoblastic leukemia (AMKL) is a rare type of acute myeloid leukemia that evolved from primitive megakaryoblasts. We report a case of non-Down syndrome AMKL with CBFA2T3::GLIS2 fusion that has not been described before in Korea. A 20-month-old girl presented with a fever and was diagnosed with AMKL after a bone marrow study and flow cytometry analysis. An RNA fusion test observed a fusion transcript between exons 9 and 2 of the CBFA2T3 and GLIS2 genes, respectively. The patient achieved complete morphological remission after induction chemotherapy. However, her prognosis was poor as measurable residual disease remained, detected using reverse transcription PCR. RNA fusion analysis could be a helpful tool to identify clinically actionable genomic markers for patient risk stratification and measurable residual disease monitoring.ope

A Case of STIL-TAL1-positive T-lymphoblastic Leukemia With a Minor Philadelphia-positive Clone

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Clinical Application of Circulating Tumor DNA Analysis

Liquid biopsy using circulating tumor DNA helps overcome the limitations of conventional tissue testing. Non-invasive molecular profiling using circulating tumor DNA is increasingly being used to diagnose cancer, stratify risk, and select targeted treatments. By understanding the biological characteristics of circulating tumor DNA and patient factors that can affect concentrations of circulating tumor DNA as well as optimizing the techniques, the clinical utilization of circulating tumor DNA tests can be improved. It is also necessary to formulate guidelines for the administration and reporting of circulating tumor DNA tests.ope

Chronic Myeloid Leukemia With Rare Variant b2a3 (e13a3) BCR-ABL1 Fusion

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Selecting short length nucleic acids localized in exosomes improves plasma EGFR mutation detection in NSCLC patients

Background: Exosomal nucleic acid (exoNA) is a feasible target to improve the sensitivity of EGFR mutation testing in non-small cell lung cancer patients with limited cell-free DNA (cfDNA) mutant copies. However, the type and size of target exoNA related to the sensitivity of EGFR mutation testing has not been explored extensively. Methods: The type and size of target exoNA related to the sensitivity of EGFR mutation testing was evaluated using ddPCR. A total of 47 plasma samples was tested using short-length exoTNA (exosomal DNA and RNA) and cfDNA. Results: The sensitivity of short-length exoTNA (76.5%) was higher than that of cfDNA (64.7%) for detecting EGFR mutations in NSCLC patients. In EGFR-mutant NSCLC patients with intrathoracic disease (M0/M1a) or cases with low-copy T790M, the positive rate was 63.6% (N = 7/11) and 45.5% (N = 5/11) for short-length exoTNA and cfDNA, respectively. On average, the number absolute mutant copies of short-length exoTNA were 1.5 times higher than that of cfDNA. The mutant allele copies (Ex19del and T790M) in short-length exoTNA were relatively well preserved at 4 weeks after storage. The difference (%) in absolute mutant allele copies (Ex19del) between 0 days and 4 weeks after storage was - 61.0% for cfDNA. Conclusion: Target nucleic acids and their size distribution may be critical considerations for selecting an extraction method and a detection assay. A short-length exoTNA (200 bp) contained more detectable tumor-derived nucleic acids than exoDNA (~ 200 bp length or a full-length) or cfDNA. Therefore, a short-length exoTNA as a sensitive biomarker might be useful to detect EGFR mutants for NSCLC patients with low copy number of the mutation target.ope

Hereditary Spastic Paraplegia with Axonal Sensorimotor Polyneuropathy in a Korean Family Caused by Pathogenic Variant of KIF5A (c.611G>A)

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A comparative study of next-generation sequencing and fragment analysis for the detection and allelic ratio determination of FLT3 internal tandem duplication

Background: Currently, FLT3 internal tandem duplication (ITD) is tested by fragment analysis. With next-generation sequencing (NGS), however, not only FLT3 ITD but also other mutations can be detected, which can provide more genetic information on disease. Methods: We retrospectively reviewed the results of two tests-fragment analysis and a custom-designed, hybridization capture-based, targeted NGS panel-performed simultaneously. We used the Pindel algorithm to detect FLT3 ITD mutations. Results: Among 277 bone marrow aspirate samples tested by NGS and fragment analysis, the results revealed 99.6% concordance in FLT3 ITD detection. Overall, the allele frequency (AF) attained by NGS positively correlated with the standard allelic ratio (AR) attained by fragment analysis, with a Spearman correlation coefficient (r) of 0.757 (95% confidence interval: 0.627-0.846; p < 0.001). It was concluded that an AF of 0.11 attained by NGS is the most appropriate cutoff value (with 85.3% sensitivity and 86.7% specificity) for high mutation burden criterion presented by guidelines. Conclusion: Sensitive FLT3 ITD detection with comprehensive information of other mutation offered by NGS could be a useful tool in clinical laboratories. Future studies will be needed to evaluate and standardize NGS AF cutoff to predict actual clinical outcomes.ope

Sporadic Hemiplegic Migraine Presenting ATP1A2 Mutation in Korea

Hemiplegic migraine (HM) is a rare form of migraine, characterized by migraine with reversible motor weakness. HM can be divided into sporadic and familiar HM based on familiarity. Mutations in CACNA1A, ATP1A2 and SCN1A were identified in familiar HM. We present a patient with sporadic HM exhibiting recurrent hemiplegia, mental change and fever along with headache attacks. During the hemiplegia, he showed perfusion delay in left middle cerebral artery territory. Genetic panel test revealed a likely pathogenic varia nt in ATP1A2.ope