[Genetic testing and prenatal diagnosis for a Chinese pedigree affected with Waardenburg syndrome type 4C due to heterozygous deletion of SOX10 gene].

OBJECTIVE: To explore the genetic basis for a Chinese pedigree featuring congenital profound syndromic deafness and chronic constipation, and provide prenatal diagnosis for a high-risk fetus. METHODS: Whole-exome sequencing was carried out to analyze the sequences of genes associated with hereditary deafness, and multiplex ligation-dependent probe amplification (MLPA) was used to verify the candidate variant in the proband's parents and the fetus. RESULTS: The proband was found to have harbored a heterozygous deletion of SOX10, a pathogenic gene associated with Waardenburg syndrome type 4C (WS4C). The same deletion was found in her mother (with profound syndromic deafness and chronic constipation) and the fetus, but not in her father with normal hearing. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and Association for Molecular Pathology (AMP), the SOX10 gene deletion was predicted to be a pathogenic variant (PVS1+PM2_Supporting+PP1+PP4). CONCLUSION: The pedigree was diagnosed with WS4C, which has conformed to an autosomal dominant inheritance. Deletion of the entire SOX10 gene, as a loss-of-function variant, probably underlay its pathogenesis. Above finding has facilitated genetic counseling and prenatal diagnosis for this family.

Association of autism spectrum disorder with Waardenburg syndrome in a toddler.

Waardenburg syndrome is a rare genetic condition with an incidence of 1 in 212 000. The condition is classically associated with distinctive facial features, congenital hearing loss and pigmentary changes of the hair, iris and skin. There is a paucity of literature about the association of neurodevelopmental conditions with this syndrome. We present a toddler with Waardenburg syndrome type 1 who was referred to our service for developmental delay concerns. The child was diagnosed with the condition at birth, had distinctive facial features, but the hearing was normal. The child's father also shares a similar mutation. Following a multidisciplinary assessment, the child was diagnosed to have autism spectrum disorder with possible regression. We acknowledge that there may not be a causal relationship between autism spectrum and Waardenburg syndrome. However, this highlights the need for developmental surveillance among children diagnosed with Waardenburg syndrome and to consider its association with neurodevelopmental conditions.

A 22q13.1 duplication in mosaicism including SOX10.

Waardenburg syndrome (WS) is characterized by the association of sensorineural hearing loss and pigmentation abnormalities. Among the four types, WS Type 2 (WS2) is the only one without a remarkable distinguishing feature. Here, we report a patient initially diagnosed with WS2 who exhibits a 446 kb mosaic duplication in chromosome 22q13.1, encompassing SOX10, and detected using whole genome sequencing in a trio. The patient, a 46,XY boy, presents with profound bilateral sensorineural hearing loss, right heterochromia iridium, left bright blue iris, and skin-depigmented areas in the abdomen and limbs. Vestibular and imaging tests are normal, without inner ear or olfactory bulb malformations. Bilateral cochlear implantation did not prevent language and speech delays. Moderate congenital chronic constipation and neurodevelopmental difficulties were also present. Given the few genes included in this duplicated region (only one OMIM gene with dominant inheritance), this report provides further delineation of the phenotype related to duplications encompassing the entire SOX10 gene.

A De Novo Mutation in SOX10 in a Chinese Boy with Waardenburg Syndrome Type 2.

Waardenburg syndrome is an autosomal dominant inherited syndromic hereditary hearing loss characterized by varying combinations of sensorineural hearing loss and abnormal pigmentation of the hair, skin, and inner ear. The aim of this study was to analyze the clinical phenotypes and genetic variants of a Chinese boy with Waardenburg syndrome type 2 and to explore the possible molecular pathogenesis of Waardenburg syndrome type 2. Clinical, audiological, and ophthalmologic evaluations were performed on the proband. Clinical data from the principal members in the proband's family were collected through questionnaires. Genetic analysis was conducted, including targeted next-generation sequencing of 144 known deafness genes, Sanger sequencing, and bioinformatic analysis. Waardenburg syndrome type 2was diagnosed in a 4-year-old boy according to the Waardenburg Syndrome Consortium Criteria. The novel missense mutation c.426G>T (p.Trp142Cys) was identified in SOX10 in the proband but was absent in his parents and the controls. A de novo missense mutation in SOX10 was the genetic cause of Waardenburg syndrome type 2 in the proband, which was useful for the molecular diagnosis of Waardenburg syndrome type 2.

A novel variant of the SOX10 gene associated with Waardenburg syndrome type IV.

BACKGROUND: Waardenburg syndrome (WS) is a rare genetic disorder characterized by varying degrees of sensorineural hearing loss and accumulated pigmentation in the skin, hair and iris. The syndrome is classified into four types (WS1, WS2, WS3, and WS4), each with different clinical phenotypes and underlying genetic causes. The aim of this study was to identify the pathogenic variant in a Chinese family with Waardenburg syndrome type IV. METHODS: The patient and his parents underwent a thorough medical examination. We applied whole exome sequencing to identify the causal variant on the patient and other family members. RESULTS: The patient presented with iris pigmentary abnormality, congenital megacolon and sensorineural hearing loss. The clinical diagnosis of the patient was WS4. The whole exome sequencing (WES) revealed a novel variant (c.452_456dup) in the SOX10 gene, which could be responsible for the observed pathogenic of WS4 in this patient. Our analysis suggests that this variant produces a truncated protein that contributes to the development of the disease. The genetic test confirmed the diagnosis of WS4 in the patient from the studied pedigree. CONCLUSIONS: This present study demonstrated that genetic test based on WES, an effective alternative to regular clinical examinations, helps diagnose WS4. The newly identified SOX10 gene variant can expand the understanding of WS4.

[Analysis of clinical phenotype and genetic variants among four Chinese pedigrees affected with Waardenburg syndrome].

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.

Quantitative assessment of low-level parental mosaicism of SNVs and CNVs in Waardenburg syndrome.

Waardenburg syndrome (WS) is a rare inherited autosomal dominant disorder caused by SOX10, PAX3, MITF, EDNRB, EDN3, and SNAI2. A large burden of pathogenic de novo variants is present in patients with WS, which may be derived from parental mosaicism. Previously, we retrospectively analyzed 90 WS probands with family information. And the frequency of de novo events and parental mosaicism was preliminary investigated in our previous study. In this study, we further explored the occurrence of low-level parental mosaicism in 33 WS families with de novo variants and introduced our procedure of quantifying low-level mosaicism. Mosaic single nucleotide polymorphisms (SNPs) were validated by amplicon-based next-generation sequencing (NGS); copy-number variants (CNVs) were validated by droplet-digital polymerase chain reaction (ddPCR). Molecular validation of low-level mosaicism of WS-causing variants was performed in four families (12.1%, 4/33). These four mosaic variants, comprising three SNVs and one CNV, were identified in SOX10. The rate of parental mosaicism was 25% (4/16) in WS families with de novo SOX10 variants. The lowest allele ratio of a mosaic variant was 2.0% in parental saliva. These de novo WS cases were explained by parental mosaicism conferring an elevated recurrence risk in subsequent pregnancies of parents. Considering its importance in genetic counseling, low-level parental mosaicism should be systematically investigated by personalized sensitive testing. Amplicon-based NGS and ddPCR are recommended to detect and precisely quantify the mosaicism for SNPs and CNVs.

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.

A comprehensive genotype-phenotype evaluation of eight Chinese probands with Waardenburg syndrome.

BACKGROUND: Waardenburg syndrome (WS) is the most common form of syndromic deafness with phenotypic and genetic heterogeneity in the Chinese population. This study aimed to clarify the clinical characteristics and the genetic cause in eight Chinese WS families (including three familial and five sporadic cases). Further genotype-phenotype relationships were also investigated. METHODS: All probands underwent screening for the known WS-related genes including PAX3, SOX10, MITF, EDNRB, EDN3, and SNAI2 using next-generation sequencing to identify disease-causing genes. Further validation using Sanger sequencing was performed. Relevant findings for the associated genotype-phenotype from previous literature were retrospectively analyzed. RESULT: Disease-causing variants were detected in all eight probands by molecular genetic analysis of the WS genes (SOX10(NM_006941.4): c.544_557del, c.553 C > T, c.762delA, c.336G > A; MITF(NM_000248.3): c.626 A > T; PAX3(NM_181459.4): c.838delG, c.452-2 A > G, c.214 A > G). Six mutations (SOX10:c.553 C > T, c.544_557del, c.762delA; PAX3: c.838delG, c.214 A > G; MITF:c.626 A > T) were first reported. Clinical evaluation revealed prominent phenotypic variability in these WS patients. Twelve WS1 cases and five WS2 cases were diagnosed in total. Two probands with SOX10 mutations developed progressive changes in iris color with age, returning from pale blue at birth to normal tan. Additionally, one proband had a renal malformation (horseshoe kidneys).All cases were first described as WS cases. Congenital inner ear malformations were more common, and semicircular malformations were exclusively observed in probands with SOX10 mutations. Unilateral hearing loss occurred more often in cases with PAX3 mutations. CONCLUSION: Our findings helped illuminate the phenotypic and genotypic spectrum of WS in Chinese populations and could contribute to better genetic counseling of WS.

A Novel Variant in Paired Box 3 Gene-related with Waardenburg Syndrome Type-1 in an Afghan Family.

Waardenburg Syndrome (WS) is a congenital auditory-pigmentary syndrome. We, herein, present a case of a 1.5 year girl presenting with bilateral hearing impairment. Detailed examinations and molecular analyses of the proband and other family members were performed. A novel missense, heterozygous variant (c.253A>C (p.Lys85Gln)) was detected in the paired box 3 (PAX3) gene. For interpretation and classification of the variant, the American College of Medical Genetics and Genomics (ACMG) guideline was used. No previous report of this variant was found in the literature and we determined the variant according to the guide published in 2015 as ''likely pathogenic''. We think that the clinical and genetic characterisation of the current family will contribute to knowledge for a better understanding of the genetic background of the Afghan patients with WS. Key Words: Waardenburg syndrome, Congenital auditory-pigmentary syndrome, PAX3 gene.

Waardenburg syndrome-associated neurotrophic keratopathy in a child treated with neurotization surgery.

Waardenburg syndrome (WS) is a congenital developmental disorder characterized by congenital sensorineural hearing loss and pigmentary deficiencies in the iris, hair, and skin. Ocular associations of WS include choroidal and iris hypopigmentation and foveal hypoplasia. Possible associations include cataracts and retinal vein occlusion. We report the first case of neurotrophic cornea and relate our experience with neurotization surgery.

Establishment of an iPSC line (CPGHi005-A) from a patient with Waardenburg syndrome carrying a heterozygous SVA-F retrotransposon insertion into SOX10.

Mutations of SOX10 result in Waardenburg syndrome characterized by sensorineural hearing loss and pigmentary abnormalities, which can be found in association with a defect of migrating neural crest cells. The role of SINE-VNTR-Alu (SVA) retrotransposon insertions in disorders has only been minimally explored and there have been no reports of WS cases related to SVA retrotransposons. Here, we report the successful establishment and characterization of an iPSC line from a patient diagnosed with Waardenburg syndrome carrying an insertion of SVA in intron 2 of SOX10.