ACTG2 Variants in Pediatric Chronic Intestinal Pseudo-obstruction With Megacystis

Background/Aims@#Chronic intestinal pseudo-obstruction (CIPO) is a clinically heterogeneous syndrome characterized by compromised peristalsis and intestinal obstruction. Variants of actin gamma 2 (ACTG2), a protein crucial for correct enteric muscle contraction, have been found in CIPO patients. The aim of this study is to examine the clinical features and ACTG2 variants in Korean patients with CIPO. @*Methods@#From January 1995 to August 2020, 12 patients diagnosed with CIPO were included and genetic analysis testing of ACTG2 was performed. @*Results@#Heterozygous ACTG2 missense variants were found in 6 patients (50.0%). The p.Arg257Cys variant was found in 3 patients, and p.Arg63Gln and p.Arg178His variants were found in 1 patient each. A novel variant, p.Ile193Phe, was found in 1 patient. Three patients were diagnosed at birth, 2 at the age of 1 year, and 1 at 3 years of age. Abnormal prenatal genitourinary ultrasonographic findings were found in all 6 patients; microcolon was found in 4 patients (66.7%), and megacystis in all 6 patients. The pathology showed abnormal ganglion cells as well as myopathic findings. All patients are dependent on total parenteral nutrition and are to date alive. @*Conclusions@#ACTG2 variants are commonly found in Korean patients with CIPO. In CIPO patients with megacystis and abnormal prenatal ultrasonography, genetic testing of ACTG2 should be considered. Molecular diagnosis of CIPO is more important than pathologic diagnosis.

Molecular basis and diagnosis of thalassemia

Thalassemia is characterized by the impaired synthesis of globin chains due to disease-causing variants in α- or β-globin genes. In this review, we provide an overview of the molecular basis underlying α- and β-thalassemia, and of the current technologies used to characterize these disease-causing variants for the diagnosis of thalassemia.Understanding these molecular basis and technologies will prove to be beneficial for the accurate diagnosis of thalassemia.

Two Cases of Facioscapulohumeral Muscular Dystrophy 2 in Korea

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant muscular disorder characterized by weakness of facial, shoulder, abdominal, hip girdle, humeral, and anterior distal leg muscles, with descending progression from the face to the legs in an asymmetric pattern. In about 5% of patients with FSHD, no D4Z4 repeat contraction on chromosome 4q35 is observed;this disease entity is called FSHD2. FSHD2 is characterized by DNA hypomethylation on the 4q-subtelomeric macrosatellite repeat array D4Z4. In Korea, there have been no previous reports of FSHD2. We report the first two cases of FSHD2 in Korea, carrying c.3801delG and c.1580C>T mutations in the SMCHD1 gene, respectively. For rapid and accurate diagnosis of FSHD2, genetic analysis of the D4Z4 haplotype and methylation with next-generation sequencing are required.

Leukemic stem cell phenotype is associated with mutational profile in acute myeloid leukemia

Background/Aims@#Understanding leukemic stem cell (LSC) is important for acute myeloid leukemia (AML) treatment. However, association of LSC with patient prognosis and genetic information in AML patients is unclear. @*Methods@#Here we investigated the associations between genetic information and the various LSC phenotypes, namely multipotent progenitor (MPP)-like, lymphoid primed multipotent progenitor (LMPP)-like and granulocyte-macrophage progenitors (GMP)-like LSC in 52 AML patients. @*Results@#In secondary AML patients, MPP-like LSC was significantly higher than de novo AML (p = 0.0037). The proportion of MPP-like LSC was especially high in post-myeloproliferative neoplasm AML (p = 0.0485). There was no correlation between age and LSC phenotype. Mutations of KRAS and NRAS were observed in MPP-like LSC dominant patients, TP53 and ASXL1 mutations in LMPP-like LSC dominant patients, and CEBPA, DNMT3A and IDH1 mutations in GMP-like LSC dominant patients. Furthermore, KRAS mutation was significantly associated with MPP-like LSC expression (p = 0.0540), and TP53 mutation with LMPP-like LSC expression (p = 0.0276). When the patients were separated according to the combined risk including next generation sequencing data, the poorer the prognosis, the higher the LMPP-like LSC expression (p = 0.0052). This suggests that the dominant phenotype of LSC is one of the important factors in predicting the prognosis and treatment of AML. @*Conclusions@#LSC phenotype in AML is closely associated with the recurrent mutations which has prognostic implication. Further research to confirm the meaning of LSC phenotype in the context of genetic aberration is warranted.

Hereditary Fructose Intolerance Diagnosed in Adulthood

Hereditary fructose intolerance (HFI) is an autosomal recessive disorder caused by a mutation in the aldolase B gene. HFI patients exhibit nausea, vomiting, abdominal pain, hypoglycemia, and elevated liver enzymes after dietary fructose exposure. Chronic exposure might lead to failure to thrive, liver failure, renal failure, and, eventually, death. HFI usually manifests in infants when they are being weaned off of breastmilk. Because HFI has an excellent prognosis when patients maintain a strict restrictive diet, some patients remain undiagnosed due to the voluntary avoidance of sweet foods. In the past, HFI was diagnosed using a fructose tolerance test, liver enzyme assays or intestinal biopsy specimens. Currently, HFI is diagnosed through the analysis of aldolase B mutations. Here, HFI was diagnosed in a 41-year-old woman who complained of sweating, nausea, and vomiting after consuming sweets. She had a compound heterozygous mutation in the aldolase B gene; gene analysis revealed pathogenic nonsense (c.178C>T, p.Arg60Ter) and frameshift (c.360_363delCAAA, p.Asn120LysfsTer32) variants. This is the first report of a Korean HFI patient diagnosed in adulthood.

Establishment of Pediatric Reference Intervals for Routine Laboratory Tests in Korean Population: A Retrospective Multicenter Analysis

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.

Accuracy and Performance Evaluation of Triplet Repeat Primed PCR as an Alternative to Conventional Diagnostic Methods for Fragile X Syndrome

Background@#Conventional diagnosis of fragile X syndrome (FXS) is based on a combination of fragment analysis (FA) and Southern blotting (SB); however, this diagnostic approach is time- and labor-intensive and has pitfalls such as the possibility of missing large number alleles. Triplet repeat primed PCR (TP-PCR) is a current alternative used to overcome these limitations. We evaluated the diagnostic usefulness of TP-PCR compared with the conventional diagnostic protocol consisting of FA and/or SB in terms of allele categorization, repeat number correlation, and zygosity concordance in female genetic carriers. @*Methods@#From November 2013 to March 2018, 458 patients (326 males, 132 females) were simultaneously examined using FA and/or SB and TP-PCR by detecting CGG repeat numbers in FMR gene and diagnosed as per American College of Medical Genetics guidelines. @*Results@#The TP-PCR results showed high concordance with the FA and/or SB results for all three aspects (allele categorization, repeat number correlation, and zygosity concordance in female genetic carriers). TP-PCR detected CGG expansions ≥ 200 in all full mutation (FM) allele cases in male patients, as well as both the normal allele (NL) and FM allele in female carriers. In premutation (PM) allele carriers, the TP-PCR results were consistent with the FA and/or SB results. In terms of zygosity concordance in female genetic carriers, 12 NL cases detected by TP-PCR showed a merged peak consisting of two close heterozygous peaks; however, this issue was resolved using a 10-fold dilution. @*Conclusions@#TP-PCR may serve as a reliable alternative method for FXS diagnosis.

Molecular basis and diagnosis of thalassemia

Thalassemia is characterized by the impaired synthesis of globin chains due to disease-causing variants in α- or β-globin genes. In this review, we provide an overview of the molecular basis underlying α- and β-thalassemia, and of the current technologies used to characterize these disease-causing variants for the diagnosis of thalassemia.Understanding these molecular basis and technologies will prove to be beneficial for the accurate diagnosis of thalassemia.

Young-Onset Parkinson’s Disease with Impulse Control Disorder Due to Novel Variants of F-Box Only Protein 7

F-box only protein 7 (FBXO7) is a rare monogenic cause of hereditary Parkinson’s disease (PD) with an autosomal recessive mode of inheritance and a broad spectrum of clinical manifestations. Here, we report a de novo PD patient with onset at the age of 28 with novel compound heterozygous variants in the FBXO7 gene (c.1162C>T, p.Gln388X; c.80G>A, p.Arg27His). The clinical features of the patient were problematic impulse control disorder behaviors and pyromania, and pyramidal signs were negative. We describe the novel pathogenic variants of the FBXO7 gene with detailed clinical pictures to report the expanding genotypes and phenotypes of FBXO7-associated parkinsonism.

Three-Year Experience of an External ProficiencyTesting Survey for Next-Generation Sequencing-Based Testing for Germline Mutation

Background@#Next-generation sequencing is a powerful technology thatallows simultaneous analysis of several genes but also demands a welldesignedquality management system owing to its complexity. We aimed toanalyze the results of next-generation sequencing (NGS)-germline proficiencytesting (PT) survey performed by the Korean Association of External QualityAssessment Service during 2017–2019 to assess the current status of theNGS-based genetic testing in Korea. @*Methods@#The recent 3-year results from the PT survey were investigated.During this period, PT survey was performed twice every year with two orthree challenges per round. Correct results (%) were calculated from alltested regions; the trend by year and variation type was analyzed and theprobable causes estimated. @*Results@#During this period, the number of participating laboratoriesincreased from 5 to 22. The correct results were 97.2% in average andshowed a gradual increase with year. The most common ‘unacceptable’results were false-negative or false-positive, followed by inappropriatenomenclature and zygosity assignment. @*Conclusions@#The PT survey shows that the overall performance of NGSlaboratories in Korea is highly confident, although some improvements maybe needed. A method-based PT survey for the NGS test serves as a usefulapproach to assess the performance of NGS laboratories.

Prenatal molecular diagnosis and carrier detection of Duchenne muscular dystrophy in Korea

Purpose@#Duchenne muscular dystrophy (DMD) is the most common lethal muscular dystrophy and is caused by the genetic variants of DMD gene. Because DMD is X-linked recessive and shows familial aggregates, prenatal diagnosis is an important role in the management of DMD family. We present our experience of prenatal molecular diagnosis and carrier detection based on multiplex polymerase chain reaction (PCR), multiplex ligation-dependent probe amplification (MLPA), and linkage analysis. @*Materials and Methods@#During study period, 34 cases of prenatal diagnosis and 21 cases of carrier detection were performed at the Seoul National University Hospital. Multiplex PCR and MLPA was used to detect the exon deletions or duplications. When the DMD pathogenic variant in the affected males is unknown and no DMD pathogenic variant is detected in atrisk females, linkage analysis was used. @*Results@#The prenatal molecular diagnosis was offered to 34 fetuses. Twenty-five fetuses were male and 6 fetuses (24.0%) were affected. Remaining cases had no pathogenic mutation. We had 24 (80.0%) cases of known proband results; exon deletion mutation in 19 (79.2%) cases and duplication in 5 (20.8%) cases. Linkage analysis was performed in 4 cases in which 2 cases (50.0%) were found to be affected. In the carrier testing, among 21 cases including 15 cases of mother and 6 cases of female relative, 9 (42.9%) cases showed positive results and 12 (57.1%) cases showed negative results. @*Conclusion@#Prenatal molecular diagnosis and carrier detection of DMD are effective and feasible. They are useful in genetic counseling for DMD families.

Successful Pregnancy and Delivery with Intracytoplasmic Sperm Injection in HIV-Serodiscordant Couple: the First Case in Korea

With highly active antiretroviral therapy, human immunodeficiency virus (HIV) infection is considered to be a manageable chronic disease. The improved prognosis increases the desire of individuals with HIV to have biological offspring. With the establishment of washing protocol, no HIV transmission has been reported among more than 11,000 assisted reproduction technology (ART) cycles. Although the Acquired Immunodeficiency Syndrome Prevention Act in Korea prevents the use of HIV-infected blood, organs, tissues and semen, we recently obtained the authentic approval from the Korea Centers for Disease Control and Prevention for the practice of ART in HIV-serodiscordant couples. We report a 32-year-old HIV-seronegative female with her husband who was HIV-1 seropositive. After semen washing was performed by means of a density gradient and the swim-up technique, HIV-1 ribonucleic acid was not detected in the semen. An aliquot of processed semen was cryopreserved before ART. None of 3 cycles of intrauterine insemination was successful. After the third frozen-thawed embryo transfer following two cycles of intracytoplasmic sperm injection, an intrauterine singleton pregnancy was identified. She gave birth to a normal healthy male baby at full term by Cesarean section. She and her baby were tested for HIV during pregnancy and after delivery and the results were negative. Semen washing may be a safe ART method for HIV-serodiscordant couples who desire to have a baby in Korea.

Retinitis Pigmentosa Associated with Bardet-Biedl Syndrome with BBS9 Gene Mutation in a Korean Patient

No abstract available.

Whole Exome Sequencing Identifies Novel Genetic Alterations in Patients with Pheochromocytoma/Paraganglioma

Background@#Pheochromocytoma and paragangliomas (PPGL) are known as tumors with the highest level of heritability, approximately 30% of all cases. Clinical practice guidelines of PPGL recommend genetic testing for germline variants in all patients. In this study, we used whole exome sequencing to identify novel causative variants associated with PPGL to improve the detection of rare genetic variants in our cohort. @*Methods@#Thirty-six tested negative for pathogenic variants in previous Sanger sequencing or targeted gene panel testing for PPGL underwent whole exome sequencing. Whole exome sequencing was performed using DNA samples enriched using TruSeq Custom Enrichment Kit and sequenced with MiSeq (Illumina Inc.). Sequencing alignment and variant calling were performed using SAMtools. @*Results@#Among previously mutation undetected 36 patients, two likely pathogenic variants and 13 variants of uncertain significance (VUS) were detected in 32 pheochromocytoma-related genes. SDHA c.778G>A (p.Gly260Arg) was detected in a patient with head and neck paraganglioma, and KIF1B c.2787-2A>C in a patient with a bladder paraganglioma. Additionally, a likely pathogenic variant in BRCA2, VUS in TP53, and VUS in NFU1 were detected. @*Conclusion@#Exome sequencing further identified genetic alterations by 5.6% in previously mutation undetected patients in PPGL. Implementation of targeted gene sequencing consisted of extended genes of PPGL in routine clinical screening can support the level of comprehensive patient assessment.

Whole Exome Sequencing Identifies Novel Genetic Alterations in Patients with Pheochromocytoma/Paraganglioma

Background@#Pheochromocytoma and paragangliomas (PPGL) are known as tumors with the highest level of heritability, approximately 30% of all cases. Clinical practice guidelines of PPGL recommend genetic testing for germline variants in all patients. In this study, we used whole exome sequencing to identify novel causative variants associated with PPGL to improve the detection of rare genetic variants in our cohort. @*Methods@#Thirty-six tested negative for pathogenic variants in previous Sanger sequencing or targeted gene panel testing for PPGL underwent whole exome sequencing. Whole exome sequencing was performed using DNA samples enriched using TruSeq Custom Enrichment Kit and sequenced with MiSeq (Illumina Inc.). Sequencing alignment and variant calling were performed using SAMtools. @*Results@#Among previously mutation undetected 36 patients, two likely pathogenic variants and 13 variants of uncertain significance (VUS) were detected in 32 pheochromocytoma-related genes. SDHA c.778G>A (p.Gly260Arg) was detected in a patient with head and neck paraganglioma, and KIF1B c.2787-2A>C in a patient with a bladder paraganglioma. Additionally, a likely pathogenic variant in BRCA2, VUS in TP53, and VUS in NFU1 were detected. @*Conclusion@#Exome sequencing further identified genetic alterations by 5.6% in previously mutation undetected patients in PPGL. Implementation of targeted gene sequencing consisted of extended genes of PPGL in routine clinical screening can support the level of comprehensive patient assessment.

A Case of Fungemia with Co-isolation of Candida parapsilosis and Trichosporon asahii Confirmed by MALDI-TOF MS and D2 rRNA Sequencing

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.

Erratum: Correction of Table: Genetic Mutation Profiles in Korean Patients with Inherited Retinal Diseases

The authors regret that there were errors in Table 2 and Supplementary Table.

Genetic Mutation Profiles in Korean Patients with Inherited Retinal Diseases

BACKGROUND: Because of genetically and phenotypically heterogenous features, identification of causative genes for inherited retinal diseases (IRD) is essential for diagnosis and treatment in coming gene therapy era. To date, there are no large-scale data of the genes responsible for IRD in Korea. The aim of this study was to identify the distribution of genetic defects in IRD patients in Korea. METHODS: Medical records and DNA samples from 86 clinically diagnosed IRD patients were consecutively collected between July 2011 and May 2015. We applied the next-generation sequencing strategy (gene panel) for screening 204 known pathogenic genes associated with IRD. RESULTS: Molecular diagnoses were made in 38/86 (44.2%) IRD patients: 18/44 (40.9%) retinitis pigmentosa (RP), 8/22 (36.4%) cone dystrophy, 6/7 (85.7%) Stargardt disease, 1/1 (100%) Best disease, 1/1 (100%) Bardet-Biedl syndrome, 1/1 (100%) congenital stationary night blindness, 1/1 (100%) choroideremia, and 2/8 (25%) other macular dystrophies. ABCA4 was the most common causative gene associated with IRD and was responsible for causing Stargardt disease (n = 6), RP (n = 1), and cone dystrophy (n = 1). In particular, mutations in EYS were found in 4 of 14 autosomal recessive RP (29%). All cases of Stargardt disease had a mutation in the ABCA4 gene with an autosomal recessive trait. CONCLUSION: This study provided the distribution of genetic mutations responsible for causing IRD in the Korean patients. This data will serve as a reference for future genetic screening and treatment for Korean IRD patients.

Pitfalls of ABO Genotyping Based on Targeted Single Nucleotide Variant Analysis Due to a Nondeletional O Allele Lacking c.261delG: First Report of ABO*O.09.01 in Korea

No abstract available.

Congenital Analbuminemia in a Korean Male Diagnosed with Single Nucleotide Polymorphism in the ALB Gene: The First Case Reported in Korea

Congenital analbuminemia (CAA) is an autosomal recessive disease characterized by extremely low serum levels of albumin. CAA is caused by various homozygous or heterozygous mutations of the ALB gene. Patients often exhibit no clinical symptoms, aside from rare accompanying conditions, such as fatigue, ankle edema, and hypotension. This case report describes the case of a 28-year-old asymptomatic Korean male referred to our center with hypocalcemia, vitamin D deficiency, and hypoalbuminemia who was diagnosed with CAA. To determine the cause of hypoalbuminemia in the patient, laboratory tests, radiological examination, and DNA sequencing were performed. The patient was confirmed to not exhibit any other clinical conditions that can induce hypoalbuminemia and was diagnosed with CAA using DNA sequencing. The present case of CAA is the first to be reported in Korea.