Waardenburg syndrome type II in a Chinese pedigree caused by frameshift mutation in the SOX10 gene.

Waardenburg syndrome (WS) is a congenital hereditary disease, attributed to the most common symptoms of sensorineural deafness and iris hypopigmentation. It is also known as the hearing-pigmentation deficient syndrome. Mutations on SOXl0 gene often lead to congenital deafness and has been shown to play an important role in the pathogenesis of WS. We investigated one family of five members, with four patients exhibiting the classic form of WS2, whose DNA samples were analyzed by the technique of Whole-exome sequencing (WES). From analysis of WES data, we found that both the mother and all three children in the family have a heterozygous mutation on the Sex Determining Region Y - Box 10 (SOX10) gene. The mutation was c.298_300delinsGG in exon 2 of SOX10 (NM_006941), which leads to a frameshift of nine nucleotides, hence the amino acids (p. S100Rfs*9) are altered and the protein translation may be terminated prematurely. Further flow cytometry confirmed significant down-regulation of SOX10 protein, which indicated the SOX10 gene mutation was responsible for the pathogenesis of WS2 patients. In addition, we speculated that some other mutated genes might be related to disease phenotype in this family, which might also participate in promoting the progression of WS2.

A clinical and genetic study of 16 Japanese families with Waardenburg syndrome.

The purpose of this study is to profile the clinical and genetic features of Japanese Waardenburg syndrome (WS) patients and validate the W index. Sixteen Japanese WS families with congenital sensorineural hearing loss were included in the study. The inner canthal, interpupillary, and outer canthal distances (ICD, IPD, and OCD) were measured for all patients, and patients were screened for presence of PAX3, MITF, SOX10, and EDNRB mutations. The WS patients were clinically classified under the current W index as follows: 13 families with WS1, 2 families with WS2, and 1 family with WS4. In the 13 WS1 families, genetic tests found PAX3 mutations in 5 families, MITF mutations in 4 families, SOX10 mutations in 3 families, and EDNRB mutations in 1 family. 61% of clinically classified WS1 patients under the current W index conflicted with the genetic classification, which implies W index is not appropriate for Japanese population. Resetting the threshold of W index or novel index formulated with ethnicity matched samples is necessary for clinical classification which is consistent with genetic classification for WS patients with distinct ethnicity.

22q11.2q13 duplication including SOX10 causes sex-reversal and peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome, and Hirschsprung disease.

Diagnosis of genetic syndromes may be difficult when specific components of a disorder manifest at a later age. We present a follow up of a previous report [Seeherunvong et al., (2004); AJMGA 127: 149-151], of an individual with 22q duplication and sex-reversal syndrome. The subject's phenotype evolved to include peripheral and central demyelination, Waardenburg syndrome type IV, and Hirschsprung disease (PCWH; MIM 609136). DNA microarray analysis defined the duplication at 22q11.2q13, including SOX10. Sequencing of the coding region of SOX10 did not reveal any mutations. Our data suggest that SOX10 duplication can cause disorders of sex development and PCWH, supporting the hypothesis that SOX10 toxic gain of function rather than dominant negative activity underlies PCWH.

Waardenburg syndrome type II in a Chinese patient caused by a novel nonsense mutation in the SOX10 gene.

OBJECTIVE: Waardenburg syndrome is a congenital genetic disorder. It is the most common type of syndromic hearing impairment with highly genetic heterogeneity and proved to be related by 6 genes as follows: PAX3, MITF, SNAI2, EDN3, EDNRB and SOX10. This article aims to identify the genetic causes of a Chinese WS child patient. METHODS: A Chinese WS child was collected for clinical data collection by questionnaire survey. DNA samples of proband and his parents were extracted from peripheral blood samples. Six candidate genes were sequenced by the Trusight One sequencing panel on the illumina NextSeq 500 platform. RESULTS: A novel nonsense heterozygous mutation was found in the coding region of exon 2 in the SOX10 gene of proband. The novel nonsense heterozygous mutation could cause the replacement of the 55th lysine codon by stop codon (484T > C, C142R) and further more possibly cause terminating the protein translation in advance. However, both proband's parents had no mutation of genes above mentioned. CONCLUSION: The gene mutation of SOX10 [NM_006941.3 c.163A > T] is a novel nonsense mutation. No record of this mutation has been found in dbSNP, HGMD, 1000 Genomes Project, ClinVar and ESP6500 databases. It meets the condition of PS2 of strong evidence in 2015 ACMG Standards and Guidelines.

Waardenburg syndrome in four Mexican patients.

Waardenburg syndrome is a hereditary auditory-pigmentary syndrome. The major features include pigmentary disturbances and congenital deafness. Clinical findings are extremely variable, not only at the authors' institution but also in the literature. The authors describe four patients who presented with various clinical features and different genetic pedigree penetration.

Clinical findings in Japanese patients with Waardenburg syndrome type 2.

PURPOSE: To determine the visual characteristics of Japanese subjects with the Waardenburg syndrome type 2. METHODS: The visual functions of 11 albino patients who were identified from the screening of 240 children attending a school for children with a hearing deficit were studied. The ophthalmological examinations included eye position, visual acuity, biomicroscopy, ophthalmoscopy, visual field by confrontation or Goldmann's perimetry, stereoacuity by the Titmus test, and color vision by the Ishihara pseudoisochromatic plates. RESULTS: A combination of congenital sensory deafness and partial ocular albinism without lateral displacement of the lacrimal puncta was observed in 11 (4.6%) of the students with hearing deficit. All these children had sectorial heterochromia irides with local retinal hypopigmentation. Lid deformities were not present. The retinal vasculature was normal, and macular hypoplasty was not found. Other than 1 eye with hyperopic amblyopia, no serious visual disturbance was found in these patients. CONCLUSIONS: The 11 students were classified as having Waardenburg syndrome type 2. None had a critical visual deficit, and all had partial heterochromia irides and retinal hypopigmentation.

Waardenburg syndrome in Japanese patients. Case reports and literature review.

A 3-year-old girl (case 1) had a blue iris and albinotic fundus in the right eye and bilateral deafness. Her 6-month-old sister (case 2) had hypopigmented irides and fundi in both eyes and bilateral deafness. We found that the ratios of interinner canthal distance to interpupillary distance were less than 0.65 in normal Japanese controls. In our patients, these ratios were within the normal range, indicating the absence of dystopia canthorum. After reviewing the recent Japanese literature, we found that the hypopigmented iris and deafness seen in our patients are common in Japanese patients with Waardenburg syndrome.