Case report: Development of central precocious puberty in a girl with late-diagnosed simple virilizing congenital adrenal hyperplasia complicated with Williams syndrome.

Congenital adrenal hyperplasia (CAH) and Williams Syndrome (WS; MIM # 194050) are distinct genetic conditions characterized by unique clinical features. 21-Hydroxylase deficiency (21-OHD; MIM #201910), the most common form of CAH, arises from mutations in the CYP21A2 gene, resulting in virilization of the external genitalia in affected females, early puberty in males, and short stature. Williams syndrome, caused by a microdeletion of 7q11.23, presents with distinctive facial features, intellectual disability, unique personality traits, early puberty, and short stature. This case report describe the clinical features of a 4-year-old girl referred due to progressive virilization and developmental delay. Genetic analysis confirmed concurrent CAH and WS, identifying a novel mutation in the CYP21A2 gene (c.1442T>C). Following corticosteroid therapy initiation, the patient developed central precocious puberty. This case report delves into the pubertal change patterns in a patient affected by overlapping genetic conditions, providing valuable insights in to the intricate clinical manifestation and management of these rare complex disorders.

Identification of a novel splice variant in SEC23B gene in a patient with concomitant presence of congenital dyserythropoietic anemia II and Gilbert's syndrome.

BACKGROUND: Congenital dyserythropoietic anemia Ⅱ (CDA Ⅱ) is a rare inherited disorder of defective erythropoiesis caused by SEC23B gene mutation. CDA Ⅱ is often misdiagnosed as a more common type of clinically related anemia, or it remains undiagnosed due to phenotypic variability caused by the coexistence of inherited liver diseases, including Gilbert's syndrome (GS) and hereditary hemochromatosis. METHODS: We describe the case of a boy with genetically undetermined severe hemolytic anemia, hepatosplenomegaly, and gallstones whose diagnosis was achieved by targeted next generation sequencing. RESULTS: Molecular analysis revealed a maternally inherited novel intronic variant and a paternally inherited missense variant, c.[994-3C > T];[1831C > T] in the SEC23B gene, confirming diagnosis of CDA Ⅱ. cDNA analysis verified that the splice acceptor site variant results in two mutant transcripts, one with an exon 9 skip and one in which exons 9 and 10 are deleted. SEC23B mRNA levels in the patient were lower than those in healthy controls. The patient was also homozygous for the UGT1A1*6 allele, consistent with GS. CONCLUSION: Identification of the novel splice variant in this study further expands the spectrum of known SEC23B gene mutations. Molecular genetic approaches can lead to accurate diagnosis and management of CDA Ⅱ patients, particularly for those with GS coexisting.

Targeted Panel Sequencing Identifies an Intronic c.5225-3C>G Variant of the FBN1 Gene Causing Sporadic Marfan Syndrome with Annuloaortic Ectasia.

Marfan syndrome (MFS) is a hereditary connective tissue disease whose clinical severity varies widely. Mutations of the FBN1 gene encoding fibrillin-1 are the most common genetic cause of Marfanoid habitus; however, about 10% of MFS patients are unaware of their genetic defects. Herein, we report a Korean patient with MFS and annuloaortic ectasia caused by an intronic c.5225-3C>G variant of the FBN1 gene identified by targeted panel sequencing. The reverse transcription analysis of FBN1 revealed that the intron 43 sequence from positions c.5297-1516 to c.5297-1 was retained at the coding sequence as a consequence of the c.5225-3C>G variant enhancing a cryptic splice acceptor site (c.5297-1518_5297-1517AG) in intron 43. The retained sequence of the part of intron 43 caused the same effect as insertion mutation (NM_000138.5:c.5297_c.5298ins5297-1516_5297-1), resulting in a frameshift mutation resulting in p.Ile1767Trpfs*3. The patient underwent an urgent modified Bentall operation with a 29 mm mechanical valve for annuloaortic ectasia and severe aortic valve regurgitation. This report emphasizes the need for functional investigations into the diagnostic workflows of certain diseases or gene panels with suspected high rates of intronic variants and potential pathogenic effects. Hence, further descriptions of individuals with intronic variants causing alternative splicing expected to have pathogenic effects at different transcript levels are crucial for improving our understanding.

Comparison of In Silico Tools for Splice-Altering Variant Prediction Using Established Spliceogenic Variants: An End-User's Point of View.

Assessing the impact of variants of unknown significance on splicing has become a critical issue and a bottleneck, especially with the widespread implementation of whole-genome or exome sequencing. Although multiple in silico tools are available, the interpretation and application of these tools are difficult and practical guidelines are still lacking. A streamlined decision-making process can facilitate the downstream RNA analysis in a more efficient manner. Therefore, we evaluated the performance of 8 in silico tools (Splice Site Finder, MaxEntScan, Splice-site prediction by neural network, GeneSplicer, Human Splicing Finder, SpliceAI, Splicing Predictions in Consensus Elements, and SpliceRover) using 114 NF1 spliceogenic variants, experimentally validated at the mRNA level. The change in the predicted score incurred by the variant of the nearest wild-type splice site was analyzed, and for type II, III, and IV splice variants, the change in the prediction score of de novo or cryptic splice site was also analyzed. SpliceAI and SpliceRover, tools based on deep learning, outperformed all other tools, with AUCs of 0.972 and 0.924, respectively. For de novo and cryptic splice sites, SpliceAI outperformed all other tools and showed a sensitivity of 95.7% at an optimal cut-off of 0.02 score change. Our results show that deep learning algorithms, especially those of SpliceAI, are validated at a significantly higher rate than other in silico tools for clinically relevant NF1 variants. This suggests that deep learning algorithms outperform traditional probabilistic approaches and classical machine learning tools in predicting the de novo and cryptic splice sites.

Intergenerational Influence of Gender and the DM1 Phenotype of the Transmitting Parent in Korean Myotonic Dystrophy Type 1.

Myotonic dystrophy type 1 (DM1) is the most common autosomal-dominant disorder caused by the CTG repeat expansion of the DMPK, and it has been categorized into three phenotypes: mild, classic, and congenital DM1. Here, we reviewed the intergenerational influence of gender and phenotype of the transmitting parent on the occurrence of Korean DM1. A total of 44 parent-child pairs matched for the gender of the transmitting parent and the affected child and 29 parent-child pairs matched for the gender and DM1 phenotype of the transmitting parent were reviewed. The CTG repeat size of the DMPK in the affected child was found to be significantly greater when transmitted by a female parent to a female child (DM1-FF) (median, 1309 repeats; range, 400-2083) than when transmitted by a male parent to a male child (650; 160-1030; p = 0.038 and 0.048 using the Tukey HSD and the Bonferroni test) or by a male parent to a female child (480; 94-1140; p = 0.003). The difference in the CTG repeat size of the DMPK between the transmitting parent and the affected child was also lower when transmitted from a male parent with classic DM1 (-235; -280 to 0) compared to when it was transmitted from a female parent with mild DM1 (866; 612-905; p = 0.015 and 0.019) or from a female parent with classic DM1 (DM1-FC) (605; 10-1393; p = 0.005). This study highlights that gender and the DM1 phenotype of the transmitting parent had an impact on the CTG repeat size of the DMPK in the affected child, with greater increases being inherited from the DM1-FF or DM1-FC situations in Korean DM1.

A novel variant of the POLR3A gene in a patient with hypomyelinating POLR3-related leukodystrophy.

BACKGROUND: Hypomyelinating POLR3-related leukodystrophy is a group of rare neurological diseases characterized by degeneration of the white matter of the brain with different combinations of major clinical findings. Here we report the first Korean POLR3-related leukodystrophy caused by bi-allelic POLR3A c.1771-6C > G and novel c.1650_1661del variants. METHODS: An 18-month-old girl was admitted for evaluation of a seizure-like activity with spasticity that affected her entire body. She showed dental abnormalities, but not suspicious facial dysmorphism. She was in a bed-ridden state with severe cognitive impairments and episodes of dystonic posturing for 1-2 min. Trio exome sequencing (ES) was performed to determine the potential genetic cause of severe developmental delay with leukodystrophy in our proband. RESULTS: Trio ES revealed that bi-allelic POLR3A deleterious variants, c.1650_1661del of the exon 13, and c.1771-6C > G of the intron 13 were best candidate as causes of hypomyelinating POLR3-related leukodystrophy. Sanger sequencing confirmed the genetic origin of these POLR3A deleterious variants as autosomal recessive hereditary transmission. CONCLUSION: Our report provides additional evidence for a phenotypic continuum of hypomyelinating POLR3-related leukodystrophy caused by bi-allelic POLR3A variants. Further genetic studies are required to understand underlying pleiotropic effects of different POLR3A variants.

A Neonate with Autosomal Dominant Pseudohypoaldosteronism Type 1 Due to a Novel Microdeletion of the NR3C2 Gene at 4q31.23.

Dehydration with hyponatremia can occur from a variety of causes and can be potentially fatal to infants. Pseudohypoaldosteronism type 1 (PHA1) is a rare disease that can cause severe dehydration along with hyponatremia and hyperkalemia because of renal tubular unresponsiveness to mineralocorticoids. Autosomal dominant PHA1 (ADPHA1, OMIM #177735) is caused by inactivating mutations in the NR3C2 gene, which encodes the mineralocorticoid receptor, and it can lead to renal salt-wasting, dehydration, and failure to thrive during infancy. Here, we report a case of a 20-day-old female neonate who presented as severe dehydration with hyponatremia and polyuria. We suspected that her diagnosis might be PHA1 based on markedly elevated plasma renin activity and serum aldosterone levels. For the genetic diagnosis of PHA1, we performed targeted exome sequencing of all causative genes of PHA1, but the result was negative. We confirmed by chromosomal microarray that a novel heterozygous microdeletion was found in the 4q31.23 region spanning exons 7-9 of the NR3C2 gene, and the patient was diagnosed with ADPHA1. In conclusion, our patient is a case of ADPHA1 that developed into a salt-wasting crisis in the neonatal period due to a microdeletion of the 4q31.23 region inherited from her father.

A Profile of Glucose-6-Phosphate Dehydrogenase Variants and Deficiency of Multicultural Families in Korea.

Vivax malaria incidence in Korea is now decreased and showing a low plateau. Nowadays, vivax malaria in Korea is expected to be successfully eliminated with anti-malaria chemotherapy, primaquine, and vector control. The glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with potential hemolytic anemia after primaquine administration. This inborn disorder has a pivotal polymorphism with genetic variants and is the most prevalent X-chromosome-linked disorder. The prevalence of G6PD deficiency was previously reported negligible in Korea. As the population of multicultural families pertaining marriage immigrants and their adolescents increases, it is necessary to check G6PD deficiency for them prior to primaquine treatment for vivax malaria. The prevalence of G6PD variants and G6PD deficiency in multicultural families was performed in 7 counties and 2 cities of Jeollanam-do (Province), Gyeonggi-do, and Gangwon-do. A total of 733 blood samples of multicultural family participants were subjected to test the phenotypic and genetic G6PD deficiency status using G6PD enzyme activity quantitation kit and PCR-based G6PD genotyping kit. The G6PD phenotypic deficiency was observed in 7.8% of male adolescent participants and 3.2% of materfamilias population. Based on the PCR-based genotyping, we observed total 35 participants carrying the mutated alleles. It is proposed that primaquine prescription should seriously be considered prior to malaria treatment.

A Novel de novo Mutation in ANK1 Gene Identified through Targeted Next-Generation Sequencing in a Neonate with Hereditary Spherocytosis.

Hereditary spherocytosis (HS) is a congenital disorder of the red blood cell membrane and is characterized by hemolytic anemia, variable jaundice, and splenomegaly. In neonates, the diagnosis of HS can be difficult in the absence of family history. Herein, we describe clinical and molecular genetic findings in a Korean neonate with HS. A one-month-old girl presented with severe anemia and jaundice. Spherocytes were frequently observed on peripheral blood smear, but the erythrocyte osmotic fragility test result was normal. Targeted next-generation sequencing (NGS) revealed the patient was heterozygous for a novel frameshift mutation, c.191_194del (p.Leu64Argfs*7), in exon 3 of ANK1 gene. Family study was performed by direct sequencing, and neither of her parents carried this mutation. The patient also harbored the UGT1A1*6 allele. To the best of our knowledge, this ANK1 mutation identified by targeted NGS has not been reported previously.

Cytokine clusters as potential diagnostic markers of disease activity and renal involvement in systemic lupus erythematosus.

OBJECTIVE: To describe interactions among cytokines and to identify subgroups of systemic lupus erythematosus (SLE) patients based on cytokine levels using principal component analysis and cluster analysis. METHODS: Levels of 12 cytokines were measured using sensitive multiplex bead assays and associations with SLE features including disease activity and renal involvement were assessed. RESULTS: In a group of 203 SLE patients, strong correlations were observed between interleukin (IL)6 and interferon (IFN)γ levels (r = 0.624), IL17 and IFNγ levels (r = 0.768), and macrophage inflammatory protein (MIP)1α and MIP1ß levels (r = 0.675). Cluster analysis revealed two distinct patient groups characterized by high levels of IL8, MIP1α, and MIP1ß (group 1) or of IL2, IL6, IL10, IL12, IFNγ, and tumor necrosis factor α (group 2). Active disease was more common in group 1 (49/88, 55.7%) than in group 2 (40/115, 34.8%). More patients in group 2 had renal involvement (42/115, 36.5%) than in group 1 (22/88, 25%). CONCLUSIONS: Assessment of cytokine profiles can identify distinct SLE patient subgroups and aid in understanding clinical heterogeneity and immunological phenotypes.

Seroprevalence of Neutralizing Antibodies against Japanese Encephalitis Virus among Adolescents and Adults in Korea: A Prospective Multicenter Study.

The immunization schedule for the Japanese encephalitis (JE) vaccine in Korea is a two-dose primary series at 12-24 months of age, followed by booster doses 12 months after the second dose and at the ages of 6 and 12 years. Although the number of JE cases has markedly decreased after the universal vaccination program, JE predominantly occurs in adults. The aim of this study was to assess the age-specific prevalence of the JE-neutralizing antibody (NTAb) among adolescents and adults in Korea. A total of 1603 specimens were collected from a healthy Korean population above 15 years old in five provinces. The JE-NTAb titers were measured with the pseudotyped virus assay and considered to be positive at ≥ 1:50. The seropositivity of JE-NTAb was the highest in the 15-29 years category (>95%) and gradually began to decrease in the age group of 30-44 years (89.42%). The lowest and second lowest JE-NTAb seropositive rates were observed among those aged 70 years or older (59.77%) and those aged 55-59 years (75.24%), respectively. Subjects from Seoul exhibited the highest JE-NTAb titer in all age groups compared to other provinces. In conclusion, the JE-NTAb seropositive rates and titers have maintained appropriate levels in the general Korean population. We propose that adult immunization and boosters at 12 years of age against JE are not strongly recommended in Korea.

A case of early diagnosis of pulmonary capillary hemangiomatosis in a worker with exposure to silica.

BACKGROUND: Pulmonary capillary hemangiomatosis (PCH) is a progressive and refractory vascular disease in the lung. Pulmonary hypertension is frequently combined with PCH when capillary proliferation invades to nearby pulmonary vascular systems. It is difficult to differentiate PCH from other diseases such as pulmonary venoocclusive disease and pulmonary arterial hypertension that cause pulmonary hypertension as they frequently overlap. CASE PRESENTATION: A 29-year-old female who had worked at a bathtub factory presented with progressive exertional dyspnea for the past 2 years. Computed tomography revealed centrilobular, diffusely spreading ground-glass opacities sparing subpleural parenchyma with some cystic lesions and air-trapping in both lungs, suggesting a peculiar pattern of interstitial lung disease with airway involvement. There was not any evidence of right heart failure or pulmonary hypertension on echocardiogram, as well as radiography. Microscopic examination of the lung by thoracoscopic resection showed atypical proliferation of capillary channels within alveolar walls and interlobar septa, without invasion of large vessels. CONCLUSION: We experienced a pathologically diagnosed PCH in a young female complaining progressive dyspnea with prior exposure to occupational silica or organic solvent without elevated right ventricular systolic pressure (RVSP) who showed atypical pattern of radiologic findings.

Differing disease phenotypes of Duchenne muscular dystrophy and Moyamoya disease in female siblings of a Korean family.

BACKGROUND: Variable disease phenotypes can be influenced by several factors such as allelic variation, environmental factors, genetic modifiers, and genotype-environment interaction. Herein to the best of our knowledge, this is the first report of the coexistence of DMD and RNF213 gene mutations in a Korean family with differing disease phenotypes of Duchenne muscular dystrophy (DMD) and Moyamoya disease (MMD) in each female sibling. METHODS: Deletion or duplication of the exon in DMD was screened using multiplex ligation-dependent probe amplification (MLPA). Subsequently, single exon deletion or duplication identified by MLPA was confirmed by Sanger sequencing. On the other hand, a common missense mutation [NM_001256071.2:c.14429G>A (p.Arg4810Lys)] related to MMD in exon 60 of RNF213 was also identified by Sanger sequencing. RESULTS: Three female family members carried the same disease-causing mutations, c.9953_9954delAG of DMD and c.14429G>A of RNF213. Two (II-2 and II-3) of these siblings suffer from the disease but exhibited different DMD or MMD symptoms, while the mother (I-2) seemed almost unaffected. CONCLUSION: This report illustrates the difficulty that might be encountered in the interpretation of complex clinical manifestations when different genetic defects affecting neuromuscular and vascular diseases coexist.

Effects of Copy Number Variations on Developmental Aspects of Children With Delayed Development.

OBJECTIVE: To determine effects of copy number variations (CNV) on developmental aspects of children suspected of having delayed development. METHODS: A retrospective chart review was done for 65 children who underwent array-comparative genomic hybridization after visiting physical medicine & rehabilitation department of outpatient clinic with delayed development as chief complaints. Children were evaluated with Denver Developmental Screening Test II (DDST-II), Sequenced Language Scale for Infants (SELSI), or Preschool Receptive-Expressive Language Scale (PRES). A Mann-Whitney U test was conducted to determine statistical differences of developmental quotient (DQ), receptive language quotient (RLQ), and expressive language quotient (ELQ) between children with CNV (CNV(+) group, n=16) and children without CNV (CNV(-) group, n=37). RESULTS: Of these subjects, the average age was 35.1 months (mean age, 35.1±24.2 months). Sixteen (30.2%) patients had copy number variations. In the CNV(+) group, 14 children underwent DDST-II. In the CNV(-) group, 29 children underwent DDSTII. Among variables, gross motor scale was significantly (p=0.038) lower in the CNV(+) group compared with the CNV(-) group. In the CNV(+) group, 5 children underwent either SELSI or PRES. In the CNV(-) group, 27 children underwent above language assessment examination. Both RLQ and ELQ were similar between the two groups. CONCLUSION: The gross motor domain in DQ was significantly lower in children with CNV compared to that in children without CNV. This result suggests that additional genetic factors contribute to this variability. Active detection of genomic imbalance could play a vital role when prominent gross motor delay is presented in children with delayed development.

Hereditary spherocytosis caused by copy number variation in SPTB gene identified through targeted next-generation sequencing.

Hereditary spherocytosis (HS) is a heterogeneous genetic disorder characterized by spherocytosis on peripheral blood smear with hemolytic anemia, accompanied by signs of hemolysis. Herein, we report a 5-month-old Korean girl with HS resulting from a de novo 271 Kb microdeletion of 14q23.3. She presented with hemolytic anemia and mild splenomegaly. Spherocytosis was seen on examination of peripheral blood. Eosin-5'-maleimide (EMA) test and flow cytometric osmotic fragility test were positive. She had no relevant family history of spherocytosis. No pathogenic single nucleotide variants or small insertions/deletions were detected in HS-associated genes. Array comparative genomic hybridization analysis revealed a 271 Kb deletion at chromosome 14q23.3, encompassing the SPTB, CHURC1, GPX2, RAB15, FNTB, and MAX genes. We found a deletion affecting 5' UTR, exon 1, and part of intron 1 of the SPTB gene using targeted next-generation sequencing (NGS) analysis, suggesting that NGS may be able to identify disease-causing copy number variations (CNVs), as well as small point mutations in HS patients. In addition, chromosomal microarray may be useful in defining combined deleted genes. Additional evaluations should thus be considered in the diagnosis of HS, especially when CNV is revealed as disease-causing abnormality.

CDKN2B downregulation and other genetic characteristics in T-acute lymphoblastic leukemia.

We identified principal genetic alterations in 97.1% (99/102) of patients with T-acute lymphoblastic leukemia (T-ALL) using integrative genetic analyses, including massive parallel sequencing and multiplex ligation-dependent probe amplification (MLPA). A total of 133 mutations were identified in the following genes in descending order: NOTCH1 (66.7%), FBXW7 (19.6%), PHF6 (15.7%), RUNX1 (12.7%), NRAS (10.8%), and DNMT3A (9.8%). Copy number alterations were most frequently detected in CDKN2B, CDKN2A, and genes on 9p21.3 in T-ALL (45.1%). Gene expression data demonstrated the downregulation of CDKN2B in most cases of T-ALL, whereas CDKN2A downregulation was mainly restricted to deletions. Additional quantitative methylation analysis demonstrated that CDKN2B downregulation stemmed from deletion and hypermethylation. Analysis of 64 patients with CDKN2B hypermethylation indicated an association with an older age of onset and early T cell precursor ALL, which involved very early arrest of T cell differentiation. Genes associated with methylation and myeloid neoplasms, including DNMT3A and NRAS, were more commonly mutated in T-ALL with CDKN2B hypermethylation. In particular, a CDKN2B biallelic deletion or high methylation level (≥45%), the age of onset, and the GATA3 and SH2B3 mutations were factors associated with a poor prognosis. This study clarifies that one of the most important genetic events in T-ALL, namely, CDKN2B downregulation, occurs mechanistically via deletion and hypermethylation. Different susceptible genetic backgrounds exist based on the CDKN2B downregulation mechanism.

Chromosomal Microarray Analysis as a First-Tier Clinical Diagnostic Test in Patients With Developmental Delay/Intellectual Disability, Autism Spectrum Disorders, and Multiple Congenital Anomalies: A Prospective Multicenter Study in Korea.

BACKGROUND: To validate the clinical application of chromosomal microarray analysis (CMA) as a first-tier clinical diagnostic test and to determine the impact of CMA results on patient clinical management, we conducted a multicenter prospective study in Korean patients diagnosed as having developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), and multiple congenital anomalies (MCA). METHODS: We performed both CMA and G-banding cytogenetics as the first-tier tests in 617 patients. To determine whether the CMA results directly influenced treatment recommendations, the referring clinicians were asked to complete a 39-item questionnaire for each patient separately after receiving the CMA results. RESULTS: A total of 122 patients (19.8%) had abnormal CMA results, with either pathogenic variants (N=65) or variants of possible significance (VPS, N=57). Thirty-five well-known diseases were detected: 16p11.2 microdeletion syndrome was the most common, followed by Prader-Willi syndrome, 15q11-q13 duplication, Down syndrome, and Duchenne muscular dystrophy. Variants of unknown significance (VUS) were discovered in 51 patients (8.3%). VUS of genes putatively associated with developmental disorders were found in five patients: IMMP2L deletion, PTCH1 duplication, and ATRNL1 deletion. CMA results influenced clinical management, such as imaging studies, specialist referral, and laboratory testing in 71.4% of patients overall, and in 86.0%, 83.3%, 75.0%, and 67.3% of patients with VPS, pathogenic variants, VUS, and benign variants, respectively. CONCLUSIONS: Clinical application of CMA as a first-tier test improves diagnostic yields and the quality of clinical management in patients with DD/ID, ASD, and MCA.

Reclassification of Acute Myeloid Leukemia According to the 2016 WHO Classification.

We reviewed our leukemia database to reclassify 610 patients previously diagnosed as having acute myeloid leukemia (AML) according to the updated 2016 WHO classification. Nine patients were categorized as having myelodysplastic syndrome and myeloid neoplasms with germline predisposition. AML with recurrent genetic abnormalities accounted for 57.4% (345/601) of the patients under the 2016 WHO classification. AML with mutated NPM1 was the most common form (16.5%), with the majority associated with monocytic differentiation (63.6%). AML with double CEBPA mutations accounted for 8.3% of these cases, and the majority were previously diagnosed as AML with/without maturation (78.0%). These newly classified mutations were mutually exclusive without overlapping with other forms of AML with recurrent genetic abnormalities. AML with mutated NPM1 and AML with myelodysplasia-related changes comprised the oldest patients, whereas AML with RUNX1-RUNX1T1 included the youngest patients. The leukocyte count was highest in AML with mutated NPM1, and the percentage of peripheral blood blasts was the highest in AML with double CEBPA mutations. Our results indicate that implementation of the 2016 WHO classification of AML would not pose major difficulties in clinical practice. Hematopathologists should review and prepare genetic tests for the new classification, according to their clinical laboratory conditions.

Considerations for monitoring minimal residual disease using immunoglobulin clonality in patients with precursor B-cell lymphoblastic leukemia.

BACKGROUND: Minimal residual disease (MRD) monitoring is a powerful tool to predict the risk of relapse. Herein, we present an MRD monitoring strategy for B-cell lymphoblastic leukemia (B-ALL) using high-throughput sequencing (HTS) of immunoglobulin (Ig) clonality before implementation into routine practice. METHODS: We selected 74 bone marrow (BM) specimens from 47 patients who were diagnosed with B-ALL. Ig clonality was analyzed using both fragment analysis and HTS. The performance of Ig clonality was evaluated through comparison of the results from real-time quantitative polymerase chain reaction (qPCR) of leukemia-specific fusion transcripts and flow cytometry. RESULTS: IGH clonality was observed in all patients, and the sum of clonal burden varied (9.47%-96.77%). IGK clonality was identified in 70% of patients and availed in cases with low IGH clonal burden. The total IGH clonal burden was significantly correlated with the proportion of leukemic blasts, leukemia-specific fusion transcripts, and flow cytometry. We recognized the different responses of each clone and emerging clones originating from the trace of Ig rearrangement presented in the initial specimen. IGH clonal burden after chemotherapy represented patient outcomes well. IGH assay also provided information of repertoire diversity of IGH rearrangement. CONCLUSION: The Ig clonality assay via HTS will be a promising tool for MRD monitoring of B-ALL through an adequate strategy to identify and monitor individual clones and determine repertoire diversity.