Analysis of clinical phenotype and genetic variants among four Chinese pedigrees affected with Waardenburg syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for four Chinese pedigrees affected with Waardenburg syndrome (WS).@*METHODS@#Four WS probands and their pedigree members who had presented at the First Affiliated Hospital of Zhengzhou University between July 2021 and March 2022 were selected as the study subjects. Proband 1, a 2-year-and-11-month female, had blurred speech for over 2 years. Proband 2, a 10-year-old female, had bilateral hearing loss for 8 years. Proband 3, a 28-year-old male, had right side hearing loss for over 10 years. Proband 4, a 2-year-old male, had left side hearing loss for one year. Clinical data of the four probands and their pedigree members were collected, and auxiliary examinations were carried out. Genomic DNA was extracted from peripheral blood samples and subjected to whole exome sequencing. Candidate variants were verified by Sanger sequencing.@*RESULTS@#Proband 1, with profound bilateral sensorineural hearing loss, blue iris and dystopia canthorum, was found to have harbored a heterozygous c.667C>T (p.Arg223Ter) nonsense variant of the PAX3 gene, which was inherited from her father. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as pathogenic (PVS1+PM2_Supporting+PP4), and the proband was diagnosed with WS type I. Proband 2, with moderate sensorineural hearing loss on the right side and severe sensorineural hearing loss on the left side, has harbored a heterozygous frameshifting c.1018_1022del (p.Val340SerfsTer60) variant of the SOX10 gene. Neither of her parents has harbored the same variant. Based on the ACMG guidelines, it was classified as pathogenic (PVS1+PM2_Supporting+PP4+PM6), and the proband was diagnosed with WS type II. Proband 3, with profound sensorineural hearing loss on the right side, has harbored a heterozygous c.23delC (p.Ser8TrpfsTer5) frameshifting variant of the SOX10 gene. Based on the ACMG guidelines, it was classified as pathogenic (PVS1+PM2_Supporting+PP4), and the proband was diagnosed with WS type II. Proband 4, with profound sensorineural hearing loss on the left side, has harbored a heterozygous c.7G>T (p.Glu3Ter) nonsense variant of the MITF gene which was inherited from his mother. Based on the ACMG guidelines, the variant was classified as pathogenic (PVS1+PM2_Supporting+PP4), and the proband was diagnosed with WS type II.@*CONCLUSION@#By genetic testing, the four probands were all diagnosed with WS. Above finding has facilitated molecular diagnosis and genetic counseling for their pedigrees.

Bilateral symmetrical maculopathy and heterochromia in Waardenburg syndrome / Maculopatia simétrica bilateral e heterocromia na síndrome de Waardenburg

ABSTRACT Waardenburg syndrome is a rare congenital genetic disorder characterized by sensorineural hearing loss and pigmentary abnormalities of the hair, skin, and eyes. Based on the different clinical presentations, it is divided into four subtypes as in WS1 to WS4. This report describes a 15-year-old boy who presented with low vision and bilateral hearing loss. His visual acuity was 20/200 in both eyes. Slit-lamp examination revealed complete iris heterochromia, with one blue iris and one brown iris. Fundus examination showed symmetrical pigmentation of the retina and choroid, with atrophy of the pigment epithelium in the macular region, notably also in the eye with normal iris pigment illustrating the broad spectrum of the iris and fundus pigmentation as part of this syndrome. A carefully clinical and ophthalmological evaluation should be done to differentiate various types of Waardenburg syndrome and other associated auditory-pigmentary syndrome. Early diagnosis in some cases may be crucial for the adequate development of patients affected with this condition.

RESUMO A síndrome de Waardenburg é uma doença genética congênita rara caracterizada por perda auditiva neurossensorial e anormalidades pigmentares do cabelo, da pele e dos olhos. Com base nas diferentes apresentações clínicas, é dividida em quatro subtipos (WS1 a WS4). Este relato descreve o caso de um menino de 15 anos que apresentava baixa visão e perda auditiva bilateral. Sua acuidade visual era de 20/200 em ambos os olhos. O exame em lâmpada de fenda revelou heterocromia completa da íris, com uma íris azul e uma íris marrom. A fundoscopia mostrou pigmentação simétrica da retina e coroide, com atrofia do epitélio pigmentar na região macular, notadamente também no olho com pigmento de íris normal, ilustrando o amplo espectro de pigmentação de íris e fundo como parte dessa síndrome. Uma avaliação clínica e oftalmológica criteriosa deve ser feita para diferenciar os vários tipos de síndrome de Waardenburg e outras síndromes auditivo-pigmentares associadas. O diagnóstico precoce em alguns casos pode ser crucial para o desenvolvimento adequado dos pacientes acometidos por essa condição.

Analysis of genetic characteristics in two Chinese children of type Ⅱ Waardenburg syndrome / 中华耳鼻咽喉头颈外科杂志

Objective: To screen and analyze the mutations of MITF gene in two children of type Ⅱ Waardenburg syndrome (WS2) from different families in Yunnan,China,and to explore the possible molecular pathogenesis. Methods: With informed consent, medical history collection, physical examinations, audiological evaluation, and high resolution computer tomography (HRCT) scan of temporal bone were performed on the two WS2 probands and their family members. Genomic DNA was extracted from peripheral blood of all individuals. The coding regions including all exons, part of introns and promoters of MITF, PAX3, SOX10, SNAI2, END3, ENDRB, and KITLG genes were sequenced by high-throughput sequencing. According to the results of high-throughput sequencing, pathogenic mutations detected in the probands and their parents were verified by Sanger sequencing. Results: The proband 1 carried c.641_643delGAA mutation in the 7th exon of MITF gene, which was a frame-shift mutation resulting in an amino acid change of p.214delR. It was a de novo mutation as the parents of proband 1 showed no variation on this site. The proband 2 carried heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene, which defected the function of MITF protein. Conclusion: Genetic examinations provide important evidence for diagnosis of Waardenburg syndrome. Heterozygous mutation c.641_643delGAA and heterozygous loss of the large fragment ranging from exon 1 to exon 9 of MITF gene might be the molecular pathogenesis of the two WS2 probands in this study.

Heterocromia de íris: uma revisão das condições que podem afetar a pigmentação iridiana / Heterochromia: a review of conditions that may affect iris pigmentation

RESUMO A íris é responsável pela cor dos olhos. Ela ainda realiza o controle da quantidade de luz que penetra no olho pela pupila. Variações nos genes de cada indivíduo, além da quantidade e da qualidade de melanina na íris, determinam a cor dos olhos. A heterocromia é caracterizada por diferenças na coloração da íris de um mesmo indivíduo, sendo, na maioria das vezes, benigna. Existem basicamente três tipos de heterocromia de íris: central, setorial e completa. A heterocromia de íris pode ter como causa alterações genéticas e congênitas, relacionadas ou não a síndromes específicas, como a de Sturge-Weber, a de Waardenburg, a de Parry-Romberg e a de Horner congênita. Há também causas adquiridas, como doenças ou lesões, trauma ocular e corpos estranhos intraoculares, uso de certas medicações tópicas, siderose ocular, irites ou uveítes como a síndrome uveítica de Fuchs, dentre outras. Diante de um paciente com heterocromia de íris, deve-se entender o contexto e o curso clínico desse sinal, pois pode se tratar de uma alteração de pigmentação benigna ou existir uma doença base em curso, que requer terapêutica específica. Este artigo de revisão de literatura visa abordar as principais etiologias relacionadas à heterocromia de íris, além de discorrer sobre a anatomia e a fisiologia da coloração iridiana e sobre a fisiopatologia de suas possíveis alterações.

ABSTRACT The iris is responsible for eye color and controls the amount of light that enters the eye through the pupil. Variation in each individual's genes, besides the quantity and quality of melanin in the iris, determine eye color. Heterochromia is characterized by different colors of irises in the same individual, and it is benign in most cases. There are basically three types of heterochromia: central, partial and complete. Heterochromia can be caused by genetic and congenital alterations, which may or may not be related to specific conditions, such as Sturge-Weber syndrome, Waardenburg syndrome, Parry-Romberg syndrome and congenital Horner syndrome. It may be associated to acquired causes like diseases or injuries, such as eye trauma and intraocular foreign bodies, use of some topical medications, ocular siderosis, iritis or uveitis, such as Fuchs´ uveitis, among others. When assessing a patient with heterochromia, one must understand the context and clinical course of this signal, since it may be a benign pigmentation disorder or there may be an underlying disease, which requires specific therapy. This literature review article was set out to address the main etiologies related to heterochromia, in addition to describing the anatomy and physiology of the iris color and the pathophysiology of possible alterations.

Manifestaciones oftalmológicas compatibles con el síndrome de Waardenburg / Ophthalmological manifestations compatible with Waardenburg syndrome

RESUMEN El síndrome de Waardenburg es una enfermedad genética, con criterios diagnósticos como la distopia cantorum, las anomalías pigmentarias del iris, el hipertelorismo y la conjunción de las cejas. Se presentan dos casos de una misma familia quienes asistieron a la consulta de Oftalmología con manifestaciones compatibles con el síndrome de Waardenburg. Paciente de 12 años con asociación típica que inclu ye conjunción de las cejas, alteraciones en la pigmentación del iris (iris azul zafiro) y distopia cantorum, a los que se le une el antecedente de hipoacusia. Su madre, paciente de 37 años de edad, quien presenta la asociación típica, inclu ye alteraciones en la pigmentación del cabello (mechón de canas) y del iris (iris azul zafiro), distopia cantorum y antecedente de hipoacusia. El propósito de este estudio fue dar a conocer dos casos de la misma familia con una entidad infrecuente en la especialidad. No obstante, se pueden encontrar manifestaciones oftalmológicas que son compatibles con su diagnóstico, por lo que es elemental dirigir nuestra acción hacia una aten ción en forma interdisciplinaria y una remisión oportuna(AU)

ABSTRACT Waardenburg syndrome is a genetic disorder with diagnostic criteria such as dystopia canthorum, iris pigmentary abnormalities, hypertelorism and synophrys. A case is presented of two members of the same family who attend the ophthalmology service for manifestations compatible with Waardenburg syndrome. The two patients are a 12-year-old girl with a typical association, which includes synophrys, iris pigmentary alterations (brilliant blue iris) and dystopia canthorum, as well as a history of hypoacusis, and her 37-year-old mother, who presents the typical association, which includes alterations in the pigmentation of her hair (a forelock of white hair) and iris (brilliant blue iris), dystopia canthorum and a history of hypoacusis. The purpose of the study is to present two cases from the same family with a condition which is infrequent in the specialty. However, ophthalmological manifestations may be found which are compatible with its diagnosis, which should obviously enough lead to actions aimed at interdisciplinary care and timely referral(AU)

Waardenburg Syndrome Type IV De Novo SOX10 Variant Causing Chronic Intestinal Pseudo-Obstruction / 대한소아소화기영양학회지

Waardenburg syndrome (WS) type IV is characterized by pigmentary abnormalities, deafness and Hirschsprung's disease. This syndrome can be triggered by dysregulation of the SOX10 gene, which belongs to the SOX (SRY-related high-mobility group-box) family of genes. We discuss the first known case of a SOX10 frameshift mutation variant defined as c.895delC causing WS type IV without Hirschsprung's disease. This female patient of unrelated Kuwaiti parents, who tested negative for cystic fibrosis and Hirschsprung's disease, was born with meconium ileus and malrotation and had multiple surgical complications likely due to chronic intestinal pseudo-obstruction. These complications included small intestinal necrosis requiring resection, development of a spontaneous fistula between the duodenum and jejunum after being left in discontinuity, and short gut syndrome. This case and previously reported cases demonstrate that SOX10 gene sequencing is a consideration in WS patients without aganglionosis but with intestinal dysfunction.

Oblique transnasal wiring canthopexy via Y-V epicanthoplasty for telecanthus correction in a patient with Waardenburg syndrome

Telecanthus is a common symptom accompanied by Waardenburg syndrome, a rare genetic disorder. The optimal surgery for telecanthus correction is still debated. A 28-year-old patient with Waardenburg syndrome underwent transnasal wiring canthopexy using a Y-V epicanthoplasty for telecanthus correction. A Mini-Monoka stent was used to prevent damage to the lacrimal apparatus. The intercanthal distance decreased from 50 mm to 43.2 mm. The easily designed Y-V epicanthoplasty incision provides sufficient operative field for oblique transnasal wiring, which is effective in properly positioning the medial canthal tendon. It has minimal scarring resulting in satisfactory cosmetic outcomes.

Prenatal diagnosis of a novel SOX10 mutation in a patient with syndromic hearing loss / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a patient with syndromic hearing loss.@*METHODS@#Genomic DNA of the patient was extracted, for which 127 deafness-related genes were enriched with a chip. Following next generation sequencing, pathogenic loci in exonic regions were analyzed through comparison against the databases. Genotype of her fetus for the suspected site was determined by testing the amniotic fluid sample. qPCR method was applied to verify the deletion of a large fragment.@*RESULTS@#The proband was diagnosed with Waardenburg syndrome type 2, and had harbored a novel heterozygous deletion of the exons 3 and 4 of the SOX10 gene. Her fetus was found to carry the same deletion and presented with blue eyes and deafness after birth.@*CONCLUSION@#Waardenburg syndrome type 2 due to SOX10 gene deletion may feature autosomal dominant inheritance with incomplete penetrance. The deletion of exons 3 and 4 of the SOX10 gene probably underlies the disease in this family.

Study of gene mutation and pathogenetic mechanism for a family with Waardenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the pathogenetic mechanism of a family affected with Waardenburg syndrome.</p><p><b>METHODS</b>Clinical data of the family was collected. Potential mutation of the MITF, SOX10 and SNAI2 genes were screened. Plasmids for wild type (WT) and mutant MITF proteins were constructed to determine their exogenous expression and subcellular distribution by Western blotting and immunofluorescence assay, respectively.</p><p><b>RESULTS</b>A heterozygous c.763C>T (p.R255X) mutation was detected in exon 8 of the MITF gene in the proband and all other patients from the family. No pathological mutation of the SOX10 and SNAI2 genes was detected. The DNA sequences of plasmids of MITFand mutant MITFwere confirmed. Both proteins were detected with the expected size. WT MITF protein only localized in the nucleus, whereas R255X protein showed aberrant localization in the nucleus as well as the cytoplasm.</p><p><b>CONCLUSION</b>The c.763C>T mutation of the MITF gene probably underlies the disease in this family. The mutation can affect the subcellular distribution of MITF proteins in vitro, which may shed light on the molecular mechanism of Waardenburg syndrome caused by mutations of the MITF gene.</p>

The first Korean case of Waardenburg-Shah syndrome with novel endothelin receptor type B mutations

Waardenburg syndrome (WS) is a rare genetic disorder, including clinical features of pigmentary abnormalities of irides, skin, hair and sensorineural hearing loss and facial dysmorphism. Among the four types, WS type IV (Waardenburg-Shah syndrome) additionally represents Hirschsprung's disease. Mutations in the SOX10, END3, or EDNRB genes are known to cause WS type IV. Here, we report a 6 year-old girl who was diagnosed as WS type IV by typical clinical manifestations, including skin hypopigmentation, heterochromia of both irides, unilateral sensorineural hearing loss, mild developmental delay and Hirschsprung's disease. The diagnosis was confirmed by molecular genetic analysis of EDNRB. Two novel EDNRB mutations were identified, and each mutation was segregated from each of her parents. During the follow-up period, the patient underwent a surgery for spleen torsion and was medically managed due to recurrent enterocolitis. Also, she suffered from impaired immunity including Hirschsprung's associated enterocolitis.

Mutation analysis of seven patients with Waardenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform genetic analysis for 7 patients with Waardenburg syndrome.</p><p><b>METHODS</b>Potential mutation of MITF, PAX3, SOX10 and SNAI2 genes was screened by polymerase chain reaction and direct sequencing. Functions of non-synonymous polymorphisms were predicted with PolyPhen2 software.</p><p><b>RESULTS</b>Seven mutations, including c.649-651delAGA (p.R217del), c.72delG (p.G24fs), c.185T>C (p.M62T), c.118C>T (p.Q40X), c.422T>C (p.L141P), c.640C>T (p.R214X) and c.28G>T(p.G43V), were detected in the patients. Among these, four mutations of the PAX3 gene (c.72delG, c.185T>C, c.118C>T and c.128G>T) and one SOX10 gene mutation (c.422T>C) were not reported previously. Three non-synonymous SNPs (c.185T>C, c.128G>T and c.422T>C) were predicted as harmful.</p><p><b>CONCLUSION</b>Genetic mutations have been detected in all patients with Waardenburg syndrome.</p>

Molecular pathogenesis of Waardenburg syndrome type II resulting from SOX10 gene mutation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the molecular mechanism of Waardenburg syndrome type II (WS2) resulting from SOX10 gene mutation E248fs through in vitro experiment.</p><p><b>METHODS</b>293T cells were transiently transfected with wild type (WT) SOX10 and mutant type (MT) E248fs plasmids. The regulatory effect of WT/MT SOX10 on the transcriptional activity of MITF gene and influence of E248fs on WT SOX10 function were determined with a luciferase activity assay. The DNA binding capacity of the WT/MT SOX10 with the promoter of the MITF gene was determined with a biotinylated double-stranded oligonucleotide probe containing the SOX10 binding sequence cattgtc to precipitate MITF and E248fs, respectively. The stability of SOX10 and E248fs were also analyzed.</p><p><b>RESULTS</b>As a loss-of-function mutation, the E248fs mutant failed to transactivate the MITF promoter as compared with the WT SOX10 (P<0.01), which also showed a dominant-negative effect on WT SOX10. The WT SOX10 and E248fs mutant were also able to bind specifically to the cattgtc motif in the MITF promoter, whereas E248fs had degraded faster than WT SOX10.</p><p><b>CONCLUSION</b>Despite the fact that the E248fs has a dominant-negative effect on SOX10, its reduced stability may down-regulate the transcription of MITF and decrease the synthesis of melanin, which may result in haploinsufficiency of SOX10 protein and cause the milder WS2 phenotype.</p>

Síndrome Waardenburg. Presentación de una familia afectada / Syndrome Waardenburg. Presentation of an affected family

Fundamento: El síndrome de Waardenburg es una enfermedad genética caracterizada por anomalías de la pigmentación y sordera neurosensorial. Se describen varios tipos clínicos, con gran heterogeneidad genética, la mayoría de los casos publicados presentan un patrón de herencia autosómico dominante, aunque se describen otras formas de herencia. Objetivo: Mostrar una familia con varios miembros afectados representativa de expresividad variable. Presentación de caso: Se presenta una familia con siete enfermos donde predomina la hipoacusia de grado variable al igual que las alteraciones de la pigmentación de la piel, el pelo y el iris. El adecuado diagnóstico y asesoramiento genético, unido a la oportuna intervención con el implante coclear ha permitido la incorporación adecuada en la enseñanza normal a estos enfermos. Conclusiones: Es importante el diagnóstico oportuno para realizar acciones con la finalidad de mejorar la calidad de vida y la correcta incorporación social de estos pacientes.

Background: The syndrome of Waardenburg is a genetic illness characterized by anomalies of the pigmentation and neurosensory deafness. Several clinical types are described, with great genetic heterogeneity; most of the published cases present a pattern of autos’omico dominant inheritance, although other inheritance forms are described Objective: To show a representative family with several affected members of variable expression. Case presentation: A family is presented with seven sick persons where the hypo acoustic of variable grade prevail the same as the alterations of the pigmentation of the skin, the hair and the iris. The appropriate diagnose and genetic advice, together to the opportune intervention with the cochlear implants has allowed the adapted incorporation in the normal teaching to these sick persons Conclusions: It is important the opportune diagnosis to carry out actions with the purpose of improving the quality of life and the correct social incorporation of these patients.

Syndrome in Question

AbstractWaardenburg syndrome is an inherited disease characterized by sensorineural hearing loss, pigmentation changes and minor facial malformations. It has four clinical variants. We report the case of a girl who, like her mother, was affected by this syndrome. The diagnosis was made after detection and treatment of deafness.

Phenotypic and genetic analysis of a patient presented with Tietz/Waardenburg type II a syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the genetic cause for a patient featuring decreased pigmentation of the skin and iris, hearing loss and multiple congenital anomalies.</p><p><b>METHODS</b>Routine chromosomal banding was performed to analyze the karyotype of the patient and his parents. Single nucleotide polymorphism array (SNP array) was employed to identify cryptic chromosome aberrations, and quantitative real-time PCR was used to confirm the results.</p><p><b>RESULTS</b>Karyotype analysis has revealed no obvious anomaly for the patient and his parents. SNP array analysis of the patient has demonstrated a 3.9 Mb deletion encompassing 3p13p14.1, which caused loss of entire MITF gene. The deletion was confirmed by quantitative real-time PCR. Clinical features of the patient have included severe bilateral hearing loss, decreased pigmentation of the skin and iris and multiple congenital anomalies.</p><p><b>CONCLUSION</b>The patient, carrying a 3p13p14.1 deletion, has features of Tietz syndrome/Waardenburg syndrome type IIa. This case may provide additional data for the study of genotype-phenotype correlation of this disease.</p>

Analysis of nuclear localization and signal function of MITF protein predisposing to Warrdenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the role of dysfunction of nuclear localization signals (NLS) of MITF protein in the pathogenesis of Waardenburg syndrome.</p><p><b>METHODS</b>Eukaryotic expression plasmid pCMV-MITF-Flag was used as a template to generate mutant plasmid pCMV-MITF△NLS-Flag by molecular cloning technique in order to design the mutagenic primers. The UACC903 cells were transfected transiently with MITF and MITF△NLS plasmids, and the luciferase activity assays were performed to determine their impact on the transcriptional activities of target gene tyrosinase (TYR). The oligonucleotide 5'-GAACGAAGAAGAAGATTT-3' was subcloned into pEGFP-N1 to generate recombinant eukaryotic expression plasmid pEGFP-N1-MITF-NLS. The NIH3T3 cells were transfected separately with MITF, MITF△NLS, pEGFP-N1 and pEGFP-N1-NLS plasmids, and their subcellular distribution was observed by immunoflorescence assays.</p><p><b>RESULTS</b>Expression plasmids for the mutant MITF△NLS with loss of core NLS sequence and pEGFP-N1-NLS coupled with MITF△NLS were successfully generated. Compared with the wild-type MITF, MITF△NLS was not able to transactivate the transcriptional activities of promoter TYR and did not affect the normal function of MITF. MITF△NLS was only localized in the cytoplasm and pEGFP-N1 was found in both the cytoplasm and nucleus, whereas pEGFP-N1-NLS was mainly located in the nucleus.</p><p><b>CONCLUSION</b>This study has confirmed the localization function of NLS sequence 213ERRRRF218 within the MITF protein. Mutant MITF with loss of NLS has failed to transactivate the transcriptional activities of target gene TYR, which can result in melanocyte defects and cause WS.</p>

Clinical classification and genetic mutation study of two pedigrees with type II Waardenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the molecular etiology of two pedigrees affected with type II Waardenburg syndrome (WS2) and to provide genetic diagnosis and counseling.</p><p><b>METHODS</b>Blood samples were collected from the proband and his family members. Following extraction of genomic DNA, the coding sequences of PAX3, MITF, SOX10 and SNAI2 genes were amplified with PCR and subjected to DNA sequencing to detect potential mutations.</p><p><b>RESULTS</b>A heterozygous deletional mutation c.649_651delAGA in exon 7 of the MITF gene has been identified in all patients from the first family, while no mutation was found in the other WS2 related genes including PAX3, MITF, SOX10 and SNAI2.</p><p><b>CONCLUSION</b>The heterozygous deletion mutation c.649_651delAGA in exon 7 of the MITF gene probably underlies the disease in the first family. It is expected that other genes may also underlie WS2.</p>

Construction and analysis of recombinant eukaryotic expression plasmids for SOX10, the causative gene of Warrdenburg syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the exogenous expression and subcellular localization of wild type (WT) and mutant SOX10 proteins in vitro through generation of expression plasmids in order to reveal the pathogenesis of Waardenburg syndrome (WS).</p><p><b>METHODS</b>The plasmids pECE-SOX10 and pCMV-Flag were ligated after they were subjected to double enzyme digestion using molecular cloning technique to generate recombinant eukaryotic expression plasmid pCMV-SOX10-Flag, which was as a template to generate expression plasmids for novel mutations G37fs, G38fs and E248fs of the SOX10 gene. The constructs were verified by direct sequencing. NIH3T3 cells were transiently transfected with the expression plasmids of wide type SOX10, G37fs, G38fs and E248fs, respectively. The exogenous expression of WT SOX10 protein and mutant G37fs, G38fs and E248fs proteins were analyzed using Western blot assay, while their subcellular distribution were observed with an immunofluorescence assay.</p><p><b>RESULTS</b>The DNA sequences of expression plasmids for SOX10 and its mutant G37fs, G38fs and E248f were all correct. Both WT and mutant SOX10 proteins were detected at the expected site. WT SOX10 and E248fs proteins have only localized in the nucleus, whereas G37fs and G38fs proteins showed aberrant localization in both cytoplasm and nucleus.</p><p><b>CONCLUSION</b>Recombinant eukaryotic expression plasmids for the SOX10 gene and its mutants were successfully constructed. Preliminary analysis showed that the mutations have affected the subcellular distribution of WT SOX10 proteins, which has laid a basis for further study of the molecular mechanism of WS caused by SOX10 gene mutations.</p>

Identification of a Novel De Novo Variant in the PAX3 Gene in Waardenburg Syndrome by Diagnostic Exome Sequencing: The First Molecular Diagnosis in Korea

Waardenburg syndrome (WS) is a clinically and genetically heterogeneous hereditary auditory pigmentary disorder characterized by congenital sensorineural hearing loss and iris discoloration. Many genes have been linked to WS, including PAX3, MITF, SNAI2, EDNRB, EDN3, and SOX10, and many additional genes have been associated with disorders with phenotypic overlap with WS. To screen all possible genes associated with WS and congenital deafness simultaneously, we performed diagnostic exome sequencing (DES) in a male patient with clinical features consistent with WS. Using DES, we identified a novel missense variant (c.220C>G; p.Arg74Gly) in exon 2 of the PAX3 gene in the patient. Further analysis by Sanger sequencing of the patient and his parents revealed a de novo occurrence of the variant. Our findings show that DES can be a useful tool for the identification of pathogenic gene variants in WS patients and for differentiation between WS and similar disorders. To the best of our knowledge, this is the first report of genetically confirmed WS in Korea.

Implante coclear en síndrome de Waardenburg: nuestra experiencia / Cochlear implant in Waardenburg syndrome: our experience / Implante coclear em síndrome de Waardenburg: nossa experiência

Introducción: El síndrome de Waardenburg hace referencia a un grupo de enfermedades hereditarias que aparecen como consecuencia de una alteración de la migración de células derivadas de la cresta neural entre la octava y décima semana de gestación. De ellas derivan melanocitos que migran a la estría vascular del órgano de Corti. Estos pacientes se caracterizan por presentar hipoacusia neurosensorial congénita de grado variable y alteraciones pigmentarias en piel, cabello y ojos. Su incidencia es de 1/42.000 habitantes y corresponde al 5% de hipoacusia neurosensorial sindrómica, siendo la causa más frecuente con patrón de herencia dominante. Método: Revisión de 4 pacientes menores de 18 años, con síndrome de Waardenburg asociado a hipoacusia neurosensorial severa a profunda, uni o bilateral, implantados en nuestro servicio. Se estudiaron todos los pacientes con audiometría tonal, logoaudiometría, potenciales evocados auditivos de tronco, tomografía computada y resonancia magnética. Además todos los pacientes contaban con estudio genético, psicodiagnóstico y seguimiento por pediatría, dermatología y oftalmología. Resultados: Todos nuestros pacientes presentaron telemetrías de impedancia normales, sus implantes fueron encendidos al mes postquirúrgico y en todos los casos se registraron buenos resultados audiológicos y mejoría en su calidad de vida. Conclusiones: Creemos importante conocer los aspectos básicos de esta patología para poder realizar una derivación pertinente y una atención en forma interdisciplinaria del paciente. La colocación de implantes cocleares en este grupo de pacientes con hipoacusia neurosensorial severa a profunda es satisfactorio.

Background: Waardenburg syndrome refers to agroup of inherited diseases that occur due to alteredmigration of cells derived from neural crest betweenthe eighth and tenth week of pregnancy. Ofthose derived melanocytes that migrate to the groovevascular organ of Corti. These patients are characterizedby congenital sensorineural hearing lossof variable degree and pigmentary changes in skin,hair and eyes. Its incidence is 1/42000 inhabitants and corresponds to 5% of syndromic sensorineuralhearing loss being the most common cause with dominantinheritance pattern. Method: Review of 4 patients under 18 years withWaardenburg syndrome associated with severeto profound sensorineural hearing loss, unilateralor bilateral, implanted in our service. All patientswere studied with audiometry, speech perceptiontest, brain stem auditory evoked responses, CT andMRI. Additionally, all patients had genetic testing,pedagogic evaluation and follow-up by pediatrics,dermatology and ophthalmology. Results: All our patients had normal impedancetelemetry, their implants were fired at postoperative month and in all cases good audiological resultsand improvement occurred in their quality of life.Conclusions: We believe that it’s important toknow the basics of this disease to make an appropriatereferral and interdisciplinary approach of the patient. Cochlear implants in this group of patientswith severe to profound sensorineural hearing lossis satisfactory.

Introdução: A síndrome de Waardenburg faz referência a um grupo de doenças hereditárias que aparecem como consequência de uma alteração da migração de células derivadas da crista neural entre a oitava e a décima semana de gestação. Delas derivam melanócitos que migram para a estria vascular do órgão de Corti. Estes pacientes se caracterizam por apresentar hipoacusia neurossensorial congênita de grau variável e alterações pigmentares na pele, cabelo e olhos. A incidência é de 1/42000 habitante-se corresponde a 5% de hipoacusia neurossensorial sindrômica sendo a causa mais frequente com padrão de herança dominante.Método: Revisão de 4 pacientes menores de 18anos, com síndrome de Waardenburg associada à hipoacusia neurossensorial severa a profunda, uniou bilateral, implantados no nosso serviço. Foram estudados todos os pacientes com audiometria tonal, logo audiometria, potenciais evocados auditivos de tronco, tomografia computadorizada e ressonância magnética. Além disso, todos os pacientes contavam com estudo genético, psicodiagnóstico e acompanhamento por pediatria, dermatologia e oftalmologia.Resultados: Todos os nossos pacientes apresentaram telemetrias de impedância normais, os seus implantes foram ligados um mês após a cirurgia e em todos os casos foram registrados bons resultados audiológicos e melhoria na sua qualidade de vida.Conclusões: Acreditamos que seja importante conhecer os aspectos básicos desta patologia para poder realizar uma derivação pertinente e um atendimento interdisciplinar do paciente. A colocação de implantes cocleares neste grupo de pacientes com hipoacusia neurossensorial severa a profunda é satisfatória.