Distinct regulation of the anterior and posterior myeloperoxidase expression by Etv2 and Gata1 during primitive Granulopoiesis in zebrafish.

Neutrophilic granulocytes are the most abundant type of myeloid cells and form an essential part of the innate immune system. In vertebrates the first neutrophils are thought to originate during primitive hematopoiesis, which precedes hematopoietic stem cell formation. In zebrafish embryos, it has been suggested that primitive neutrophils may originate in two distinct sites, the anterior (ALPM) and posterior lateral plate mesoderm (PLPM). An ETS-family transcription factor Etsrp/Etv2/ER71 has been implicated in vasculogenesis and hematopoiesis in multiple vertebrates. However, its role during neutrophil development is not well understood. Here we demonstrate using zebrafish embryos that Etv2 has a specific cell-autonomous function during primitive neutropoiesis in the anterior lateral plate mesoderm (ALPM) but has little effect on erythropoiesis or the posterior lateral plate mesoderm (PLPM) expression of neutrophil marker myeloperoxidase mpo/mpx. Our results argue that ALPM-derived neutrophils originate from etv2-expressing cells which downregulate etv2 during neutropoiesis. We further show that Scl functions downstream of Etv2 in anterior neutropoiesis. Additionally, we demonstrate that mpx expression within the PLPM overlaps with gata1 expression, potentially marking the cells with a dual myelo-erythroid potential. Intriguingly, initiation of mpx expression in the PLPM is dependent on gata1 but not etv2 function. Our results demonstrate that mpx expression is controlled differently in the ALPM and PLPM regions and describe novel roles for etv2 and gata1 during primitive neutropoiesis.

Clinical and genetic characteristics of Korean patients with Gaucher disease.

Gaucher disease (GD) is an autosomal recessive glycolipid lysosomal storage disease caused by a deficiency of the ß-glucocerebrosidase enzyme (GBA). Allelic heterogeneity in GD has been well described. To date, more than 270 different GBA mutations have been reported. In order to determine the GBA mutation spectrum in Korean GD patients, we performed GBA mutation analysis of Korean patients and identified 72 GBA mutant alleles from 36 unrelated patients (100% identification), including 60 single-nucleotide substitutions, 6 single-nucleotide deletions, 4 recombinants, 1 splicing error, and 1 complex allele. N370S, the most common GBA mutation, was not detected, and most of the Korean GBA mutations were previously known to be rare, with the exception of L444P (~21%). Three mutations, P201H, F347L+L444P, and c.630delC, are novel. Examination of the GBA mutant alleles found in 6 ethnic groups revealed that the prevalences of GBA mutant alleles in Korean patients are very different from those seen in Jewish, non-Jewish Caucasian, and Italian patients, but similar to those seen in Japanese and Chinese patients. Our data may provide greater understanding of GBA allelic heterogeneity and an Asian perspective(1) on correlations between genotypes and phenotypes, which may help further the development of better management strategies for patients with GD.

Identification of a novel recombinant mutation in Korean patients with Gaucher disease using a long-range PCR approach.

Gaucher disease (GD) is an autosomal recessive, lysosomal disorder caused by mutations in the gene for the ß-glucocerebrosidase (GBA) enzyme. Presence of the non-functional GBAP pseudogene, which shares high sequence similarity with the functional GBA gene, has made it difficult to carry out molecular analyses of GD, especially recombinant mutations. Using a long-range PCR approach that has been skillfully devised for the easy detection of GBA recombinant mutations, we identified four recombinant mutations including two gene conversion alleles, Rec 1a and Rec 8a, one reciprocal gene fusion allele, Rec 1b, and one reciprocal gene duplication allele, Rec 7b, in Korean patients with GD. Rec 8a, in which the GBAP pseudogene sequence from intron 5 to exon 11 is substituted for the GBA gene is a novel recombinant mutation. All mutations were confirmed by full sequencing of PCR amplicons and/or Southern blot analysis. These results indicate that the usage of long-range PCR may allow the rapid and accurate detection of GBA recombinant mutations and contribute to the improvement of genotyping efficiency in GD patients.

Acute promyelocytic leukemia with complex translocation t(5;17;15)(q35;q21;q22): case report and review of the literature.

The t(15;17)(q22;q21), resulting in PML-RARA fusion gene, is a characteristic chromosomal translocation in acute promyelocytic leukemia (APL). We report a pediatric APL case with a 3-way translocation: t(5;17;15)(q35;q21;q22). Complete blood cell counts of a 12-year-old girl, of pale appearance, showed pancytopenia with increased blasts. Morphology and immunophenotype of the leukemic cells were compatible with APL. Karyotype analysis showed t(5;17;15)(q35;q21;q22) and add(7)(q32). We detected the PML-RARA fusion gene by both reverse transcriptase-polymerase chain reaction and fluorescent in situ hybridization analysis. The patient underwent successful treatment with cytarabine with all-trans retinoic acid and anthracycline-based therapy.

A novel homozygous MMP2 mutation in a patient with Torg-Winchester syndrome.

Torg-Winchester syndrome (OMIM 259600) is an autosomal recessive multicentric osteolysis disorder. Mutations in the gene for matrix metalloproteinase 2 (MMP2) are involved in its pathogenesis. This is the first report of Torg-Winchester syndrome in east Asians. A 31-year-old female Korean patient had the typical clinical phenotypes of the syndrome, including shortening of trunk and limbs and severe osteolysis resulting in extremely small hands and feet. In addition, she had cord compression at the cervico-medullary junction, as well as lumbar dural ectasia. Molecular analysis revealed a novel homozygous missense mutation of MMP2, c.1217G>A (p.G406D). Gelatin zymography demonstrated a complete loss of the MMP2 activity of the mutation. Our results provide insights into the clinical and radiological features and pathogenic mechanisms of the syndrome.

Loss of Y chromosome in the malignant peripheral nerve sheet tumor of a patient with Neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is one of the most commonly inherited autosomal dominant disorders. In order to determine whether genomic alterations and/or chromosomal aberrations involved in the malignant progression of NF1 were present in a Korean patient with NF1, molecular and cytogenetic analyses were performed on the pathologically normal, benign, and malignant tissues and primary cells cultured from those tissues of the patient. The comparative genomic hybridization (CGH) array revealed a Y chromosome loss in the malignant peripheral nerve sheet tumor (MPNST) tissue. G-banding analysis of 50 metaphase cells showed normal chromosomal patterns in the histopathologically normal and benign cultured cells, but a mosaic Y chromosome loss in the malignant cells. The final karyotype for the malignant cells from MPNST tissue was 45,X,-Y[28]/46,XY[22]. The data suggest that the somatic Y chromosome loss may be involved in the transformation of benign tumors to MPNSTs.

Hereditary palmoplantar keratoderma and deafness resulting from genetic mutation of Connexin 26.

Gap junctions, which mediate rapid intercellular communication, consist of connexins, small transmembrane proteins that belong to a large family of proteins found throughout the species. Mutations in the GJB2 gene, encoding Connexin 26, can cause nonsyndromic autosomal recessive or dominant hearing loss with or without skin manifestations. A 3-yr-old Korean female and her mother presented to our clinic with diffuse hyperkeratosis of the palms and soles (May 3, 2007). Skin biopsies from the soles of both patients demonstrated histopathological evidence of palmoplantar keratoderma. The patient and a number of her maternal family members also had congenital hearing loss. The combination of congenital hearing loss and palmoplantar keratoderma, inherited as an autosomal dominant trait, led us to test for a mutation in the GJB2 gene in both patients. The results showed the R75W mutation of the GJB2 gene in both. In conclusion, the simultaneous occurrence of a GJB2 mutation in a mother and daughter suggests that R75W mutation cause autosomal dominant hearing loss presenting with palmoplantar keratoderma. To the best of our knowledge, this is the first report of a GJB2 mutation associated with syndromic autosomal dominant hearing loss and palmoplantar keratoderma in a Korean family.

The Global State of the Genetic Counseling Profession.

The profession of genetic counseling (also called genetic counselling in many countries) began nearly 50 years ago in the United States, and has grown internationally in the past 30 years. While there have been many papers describing the profession of genetic counseling in individual countries or regions, data remains incomplete and has been published in diverse journals with limited access. As a result of the 2016 Transnational Alliance of Genetic Counseling (TAGC) conference in Barcelona, Spain, and the 2017 World Congress of Genetic Counselling in the UK, we endeavor to describe as fully as possible the global state of genetic counseling as a profession. We estimate that in 2018 there are nearly 7000 genetic counselors with the profession established or developing in no less than 28 countries.

Cochlear implantation and connexin expression in the child with keratitis-ichthyosis-deafness syndrome.

We report one child with keratitis-ichthyosis-deafness (KID) syndrome. The child showed sparse, short scalp and body hairs, ichthyotic skin, bilateral sensorineural hearing loss, and visual loss. These are associated with a nucleotide substitution, 148G>A, which results in amino acid change in codon 50 of gap junctional protein connexin (Cx) 26. Immunohistochemistry of skins showed up-regulation of Cx26 and down-regulation of Cx43. He has benefited from cochlear implantation for hearing even though low visual function and skin problems with high risk of infections. This is the very rare report about Cx expression in skins and cochlear implantation in KID syndrome.

Phenotypic Analysis of Korean Patients with Abnormal Chromosomal Microarray in Patients with Unexplained Developmental Delay/Intellectual Disability.

PURPOSE: The present study aimed to investigate chromosomal microarray (CMA) and clinical data in patients with unexplained developmental delay/intellectual disability (DD/ID) accompanying dysmorphism, congenital anomalies, or epilepsy. We also aimed to evaluate phenotypic clues in patients with pathogenic copy number variants (CNVs). MATERIALS AND METHODS: We collected clinical and CMA data from patients at Konyang University Hospital between September 2013 and October 2014. We included patients who had taken the CMA test to evaluate the etiology of unexplained DD/ID. RESULTS: All of the 50 patients identified had DD/ID. Thirty-nine patients had dysmorphism, 19 patients suffered from epilepsy, and 12 patients had congenital anomalies. Twenty-nine of the 50 patients (58%) showed abnormal results. Eighteen (36%) were considered to have pathogenic CNVs. Dysmorphism (p=0.028) was significantly higher in patients with pathogenic CNVs than in those with normal CMA. Two or more clinical features were presented by 61.9% (13/21) of the patients with normal CMA and by 83.3% (15/18) of the patients with pathogenic CMA. CONCLUSION: Dysmorphism can be a phenotypic clue to pathogenic CNVs. Furthermore, pathogenic CNV might be more frequently found if patients have two or more clinical features in addition to DD/ID.

Genetic analysis of early endocrine pancreas formation in zebrafish.

Endocrine pancreas of zebrafish consist of at least four different cell types that function similarly to mammalian pancreatic islet. No mutants specifically affecting formation of the endocrine pancreas have been identified during the previous large-scale mutagenesis screens in zebrafish due to invisibility of a pancreatic islet. We combined in situ hybridization method to visualize pancreatic islet with an ethyl-nitroso-urea mutagenesis screen to identify novel genes involved in pancreatic islet formation in zebrafish. We screened 900 genomes and identified 11 mutations belonging to nine different complementation groups. These mutants fall into three major phenotypic classes displaying severely reduced insulin expression, reduced insulin expression with abnormal islet morphology, or abnormal islet morphology with relatively normal number of insulin expressing cells. Seven of these mutants do not have any other visible phenotypes associated. These mutations affect different processes in pancreatic islet development. Additional analysis on glucagon and somatostatin cell specification revealed that somatostatin cells are specified at a separate domain from insulin cells whereas glucagon cells are specified adjacent to insulin cells. Furthermore, glucagon cells and somatostatin cells are always associated with insulin cells in mutants that have scattered insulin expression. These data indicate that there are separate mechanisms regulating endocrine cell migration, proliferation, and differentiation. Further study on these mutants will reveal important information on novel genes involved in pancreatic islet cell specification and morphogenesis.

Identifying the KAT6B Mutation via Diagnostic Exome Sequencing to Diagnose Say-Barber-Biesecker-Young-Simpson Syndrome in Three Generations of a Family.

Diagnostic exome sequencing (DES) is a powerful tool to analyze the pathogenic variants leading to development delay (DD) and intellectual disability (ID). Recently, heterozygous de novo mutation of the histone acetyltransferase encoding gene KAT6B has been recognized as causing a syndrome with congenital anomalies and intellectual disability, namely Say-Barber-Biesecker-Young-Simpson (SBBYS) syndrome. Here we report a case of SBBYS syndrome in a third generation Korean family affected with a missense mutation in KAT6B, c.2292C>T p.(His767Tyr) identified by DES. This is the first confirmed familial inherited mutation of the KAT6B reported worldwide. Our case emphasizes again the importance of basic physical examination and taking a family history. Furthermore, advances in genetic diagnostic tools are becoming key to identifying the etiology of DD and ID. This allows a physiatrist to predict the disease's clinical evolution with relative certainty, and offer an appropriate rehabilitation plan for patients.

Mutational spectrum of type I collagen genes in Korean patients with osteogenesis imperfecta.

Mutations in the type I collagen genes COL1A1 and COL1A2 are responsible for the dominantly inherited connective tissue disorder osteogenesis imperfecta (OI). The severity of OI is diverse, ranging from perinatal lethality to a very mild phenotype that is characterized by normal stature and the absence of deformities. Although there have been several studies on the mutational spectra of COL1A1 and/or COL1A2 in Western populations, very few cases have been reported from Asia. In this study, we investigated 67 unrelated Korean probands with OI and used nucleotide sequence analysis to detect COL1A1 and COL1A2 mutations. Thirty-five different mutations were identified in the two genes, including 24 novel mutations. Among the 35 kinds of detected mutations, 15 were glycine substitutions (seven in COL1A1 and eight in COL1A2), one was a nonsense mutation, four were frameshift mutations in COL1A1, three were in-frame duplications in COL1A2, and 12 were splice site mutations (seven in COL1A1 and five in COL1A2). Until now, mutations in the COL1A1 and COL1A2 genes known to cause OI were unique and rarely repeated in other families. Interestingly, the c.982G>A (p.Gly328Ser) mutation in COL1A2 was found recurrently and was the causative mutation in five independent OI probands. Haplotype analysis of the COL1A2 gene revealed that four probands from five independent OI probands with c.982G>A (p.Gly328Ser) had a common haplotype. Our clinical data showed the heterogeneity even within a specific genotype, which suggested the complex expression of this disease.

Y chromosome loss and other genomic alterations in hepatocellular carcinoma cell lines analyzed by CGH and CGH array.

Hepatocellular carcinoma (HCC) is one of the most frequently occurring malignant tumors worldwide. The incidence of HCC is much higher in males than in females. In order to clarify the molecular basis of the male predominance in HCC, we have characterized the detailed genomic alterations in 5 hepatitis B virus integrated Korean HCC cell lines using G-banding, comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), PCR, and CGH array. The commonest alterations were observed in chromosome 7 and Y, as well as chromosomal regions 1q, 8q, 4q, and 16q. The most frequent aberration of genomic material was gain of 1q and loss of chromosome Y. Significant loss of DNA copy number of the cancer related genes that are located on chromosome Y was detected by CGH array. By investigating the karyotypes of the previously reported 21 male HCC cell lines, we found 18 HCC cell lines with Y chromosome loss, indicating that this loss is a significant feature of HCC cell lines. We propose that Y chromosome loss in HCC cell lines may be responsible for the preponderance of males in HCC and its significance may lead to further studies for better understanding of carcinogenesis in HCC.

Wnt5 signaling in vertebrate pancreas development.

BACKGROUND: Signaling by the Wnt family of secreted glycoproteins through their receptors, the frizzled (Fz) family of seven-pass transmembrane proteins, is critical for numerous cell fate and tissue polarity decisions during development. RESULTS: We report a novel role of Wnt signaling in organogenesis using the formation of the islet during pancreatic development as a model tissue. We used the advantages of the zebrafish to visualize and document this process in living embryos and demonstrated that insulin-positive cells actively migrate to form an islet. We used morpholinos (MOs), sequence-specific translational inhibitors, and time-lapse imaging analysis to show that the Wnt-5 ligand and the Fz-2 receptor are required for proper insulin-cell migration in zebrafish. Histological analyses of islets in Wnt5a(-/-) mouse embryos showed that Wnt5a signaling is also critical for murine pancreatic insulin-cell migration. CONCLUSION: Our results implicate a conserved role of a Wnt5/Fz2 signaling pathway in islet formation during pancreatic development. This study opens the door for further investigation into a role of Wnt signaling in vertebrate organ development and disease.

Lateral line, nervous system, and maternal expression of Frizzled 7a during zebrafish embryogenesis.

We have isolated and mapped a new wnt receptor frizzled family member, zebrafish frizzled 7a. Fz7a and a previously reported zebrafish fz7 (El-Messaoudi and Renucci, 2001) make an orthologous gene pair, however, they display distinct expression patterns. Fz7a shows strong maternal as well as zygotic expression. Fz7a transcript is enriched dorsally starting with the shield stage. At the end of gastrulation, Fz7a is abundantly expressed within anterior neuroectoderm and expressed more weakly within lateral mesoderm. Fz7a is detected during somitogenesis within the central nervous system, somatic and posterior lateral mesoderm. At 24hpf, fz7a is expressed in migrating lateral line primordium. At 48hpf, fz7a is detected in the ear, pectoral fin bud, and within neuromasts, which had originated from the lateral line primordium. Radiation hybrid mapping using panel LN54 (Hukriede et al., 1999) places fz7a on linkage group 6, linked to the marker fi11h08 (distance 0.00cR, LOD score 14.1). To prove that fz7 and fz7a are indeed different genes we mapped fz7 as well using the same LN54 panel. Fz7 mapped to linkage group 9 with a LOD of 12.5, 27.31 cR from wnt 10a in between markers IBD2759 and fb50e04.

Childhood X-linked adrenoleukodystrophy: clinical-pathologic overview and MR imaging manifestations at initial evaluation and follow-up.

X-linked adrenoleukodystrophy (ALD) is a rare metabolic disorder caused by peroxisomal enzyme failure. Several phenotypes can be distinguished on the basis of clinical onset and manifestations. Childhood cerebral X-linked ALD is the most severe phenotype, resulting in rapid neurologic deterioration and early death. Patients with this disease may be hospitalized with far-advanced central nervous system (CNS) lesions or may complain of symptoms similar to those of certain psychiatric disorders, possibly leading to a wrong diagnosis. Although the general prognosis for patients with childhood cerebral X-linked ALD is still poor, new treatment modalities have been introduced, some of which are helpful in relieving clinical symptoms and prolonging life. With the introduction of these new therapies and increased clinical detection of childhood cerebral X-linked ALD, brain magnetic resonance (MR) imaging has become an essential tool for initial and follow-up evaluation. MR imaging allows early detection of CNS lesions and helps differentiate childhood cerebral X-linked ALD from other disorders. The characteristic MR imaging features of childhood cerebral X-linked ALD have been well documented, although most radiologists have limited experience with serial follow-up MR imaging in this context. Familiarity with the clinical-pathologic manifestations and progressive MR imaging features of childhood cerebral X-linked ALD will be helpful in evaluating affected patients.

A Korean family with KBG syndrome identified by ANKRD11 mutation, and phenotypic comparison of ANKRD11 mutation and 16q24.3 microdeletion.

KBG syndrome is a rare disease characterized by intellectual disability, typical craniofacial dysmorphism, macrodontia of the upper central incisors, short stature, and skeletal anomalies. Recently, ANKRD11 was identified as a gene that is responsible for the disease. In addition, microdeletion of 16q24.3, including ANKRD11, has been reported to result in the KBG syndrome phenotype. Herein, we discuss a Korean family with KBG syndrome, as identified by ANKRD11 gene mutation. The patients included a nine-month-old boy and his 21-month-old sister who failed to thrive and have delayed development. Chromosomal microarray was performed to identify the underlying genetic cause, but the results showed no abnormalities. However, the mother of the children was found to have features similar to her children. Therefore, we strongly suspected an autosomal-dominant inherited disease and performed whole exome sequencing. A mutation of ANKRD11 gene was found in all patients, and the frameshift variant c.2395-2398delAAAG was confirmed. Clinical manifestations of the patients were consistent with KBG syndrome. We reviewed all reported cases with confirmed ANKRD11 mutation or 16q24.3 microdeletion including ANKRD11. As a result, we conclude that severe short stature, intellectual disability, and macrodontia are the main characteristics in KBG syndrome related to ANKRD11 mutation.

ACVR1R206H receptor mutation causes fibrodysplasia ossificans progressiva by imparting responsiveness to activin A.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by episodically exuberant heterotopic ossification (HO), whereby skeletal muscle is abnormally converted into misplaced, but histologically normal bone. This HO leads to progressive immobility with catastrophic consequences, including death by asphyxiation. FOP results from mutations in the intracellular domain of the type I BMP (bone morphogenetic protein) receptor ACVR1; the most common mutation alters arginine 206 to histidine (ACVR1(R206H)) and has been thought to drive inappropriate bone formation as a result of receptor hyperactivity. We unexpectedly found that this mutation rendered ACVR1 responsive to the activin family of ligands, which generally antagonize BMP signaling through ACVR1 but cannot normally induce bone formation. To test the implications of this finding in vivo, we engineered mice to carry the Acvr1(R206H) mutation. Because mice that constitutively express Acvr1[R206H] die perinatally, we generated a genetically humanized conditional-on knock-in model for this mutation. When Acvr1[R206H] expression was induced, mice developed HO resembling that of FOP; HO could also be triggered by activin A administration in this mouse model of FOP but not in wild-type controls. Finally, HO was blocked by broad-acting BMP blockers, as well as by a fully human antibody specific to activin A. Our results suggest that ACVR1(R206H) causes FOP by gaining responsiveness to the normally antagonistic ligand activin A, demonstrating that this ligand is necessary and sufficient for driving HO in a genetically accurate model of FOP; hence, our human antibody to activin A represents a potential therapeutic approach for FOP.

Clinical and neuroradiological features of patients with spinocerebellar ataxias from Korean kindreds.

BACKGROUND: Comparative studies of clinical and magnetic resonance imaging findings in patients with spinocerebellar ataxias (SCAs) have been seldom reported. OBJECTIVE: To investigate clinical, genetic, and neuroradiological characteristics of SCAs in Korean kindreds. SETTING: University hospital. PATIENTS AND METHODS: Molecular analysis of SCA types 1, 2, 3, 6, and 7 and dentatorubral pallidoluysian atrophy and magnetic resonance imaging were performed in 67 patients with ataxia. RESULTS: The overall prevalence of 6 types of SCAs was 54% (36 of 67 patients), irrespective of patients' family histories. The most frequent type was SCA7 (11 patients, 16%), followed by SCA3 and SCA6 (10 patients, 15% for both). Certain clinical features suggested specific gene defects, although overlap among the 6 SCA subtypes was broad: visual disturbance was noted in patients with SCA3 and SCA6, dystonia in 1 patient with SCA6, and sporadic ataxia without pigmentary retinopathy in 1 patient with SCA7. Compared with the control subjects, patients with SCAs and multisystem atrophy had a significant enlargement of the fourth ventricle and atrophy of the cerebellum (P<.01). An inverse correlation between the pontine area and the degree of cerebellar atrophy was found in patients with multisystem atrophy (r = -0.73) but not in patients with SCAs. Magnetic resonance imaging revealed significant differences in pattern of morphological alterations among patients with different SCA gene mutations. A similar finding was observed in SCA patients with atypical phenotype. CONCLUSION: The clinical and neuroradiological characteristics of Korean patients with SCAs might be helpful in detecting underlying gene mutations.