Nonsense mutations in the PAX3 gene cause Waardenburg syndrome type I in two Chinese patients

Department of Otolaryngology Head and Neck Surgery, First Affiliated Hospital to Chinese General Hospital of PLA, Beijing 100037, China.
Chinese medical journal (Impact Factor: 1.05). 02/2007; 120(1):46-9.
Source: PubMed


Waardenburg syndrome type I (WS1) is an autosomal dominant disorder characterized by sensorineural hearing loss, pigmental abnormalities of the eye, hair and skin, and dystopia canthorum. The gene mainly responsible for WS1 is PAX3 which is involved in melanocytic development and survival. Mutations of PAX3 have been reported in familiar or sporadic patients with WS1 in several populations of the world except Chinese. In order to explore the genetic background of Chinese WS1 patients, a mutation screening of PAX3 gene was carried out in four WS1 pedigrees.
A questionnaire survey and comprehensive clinical examination were conducted in four Chinese pedigrees of WS1. Genomic DNA from each patient and their family members was extracted and exons of PAX3 were amplified by PCR. PCR fragments were ethanol-purified and sequenced in both directions on an ABI_Prism 3100 DNA sequencer with the BigDye Terminator Cycle Sequencing Ready Reaction Kit. The sequences were obtained and aligned to the wild type sequence of PAX3 with the GeneTool program.
Two nonsense PAX3 mutations have been found in the study population. One is heterozygous for a novel nonsense mutation S209X. The other is heterozygous for a previously reported mutation in European population R223X. Both mutations create stop codons leading to truncation of the PAX3 protein.
This is the first demonstration of PAX3 mutations in Chinese WS1 patients and one of the few examples of an identical mutation of PAX3 occurred in different populations.

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    • "Heterozygous mutations in PAX3 have been reported in familial and sporadic WS1, while heterozygous or homozygous mutations have been detected in patients with WS3 [8,13,24,25]. Although many mutations have been identified in Caucasians, several cases have been determined in the Chinese population [26,27]. Fundus changes for WS1 patients with PAX3 mutations have not been reported. "
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    ABSTRACT: To detect paired box gene 3 (PAX3) mutations and associated phenotypes in Chinese patients with Waardenburg syndrome type 1 (WS1). Five unrelated families with suspected WS1 were selected from our Genomic DNA Repository for Hereditary Eye Diseases. The coding and adjacent intronic regions of PAX3 were amplified by polymerase chain reaction and the amplicons were then analyzed by cycle sequencing. Variations detected were further evaluated in available family members as well as one hundred controls with heteroduplex-single strand conformational polymorphism (heteroduplex-SSCP) analysis and/or clone sequencing. Three novel and two known mutations in PAX3 were detected in five patients, respectively: c.567_586+17del (p.Asp189_Gln505delinsGluGlyGlyAlaLeuAlaGly), c.456_459dupTTCC (p.Ile154PhefsX162), c.795_800delCTGGTT (p.Trp266_Phe267del), c.799T>A (p.Phe267Ile), and c.667C>T (p.Arg223X). Two novel mutations proved to be de novo as their parents did not carry the mutations. All five patients with PAX3 mutations had dystopia canthorum and different iris color and fundi between their two eyes. However, none had white forelock, skin hypopigmentation, and deafness. Our findings expand the frequency and spectrum of PAX3 mutations and ethnic-related phenotypes in Chinese patients with WS1. De novo mutations in PAX3 have not been reported before.
    Full-text · Article · Jun 2010 · Molecular vision
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    ABSTRACT: Waardenburg syndrome (WS) is characterized by the association of pigmentation abnormalities, including depigmented patches of the skin and hair, vivid blue eyes or heterochromia irides, and sensorineural hearing loss. However, other features such as dystopia canthorum, musculoskeletal abnormalities of the limbs, Hirschsprung disease, or neurological defects are found in subsets of patients and used for the clinical classification of WS. Six genes are involved in this syndrome: PAX3 (encoding the paired box 3 transcription factor), MITF (microphthalmia-associated transcription factor), EDN3 (endothelin 3), EDNRB (endothelin receptor type B), SOX10 (encoding the Sry bOX10 transcription factor), and SNAI2 (snail homolog 2), with different frequencies. In this review we provide an update on all WS genes and set up mutation databases, summarize molecular and functional data available for each of them, and discuss the applications in diagnostics and genetic counseling. Hum Mutat 31, 1–16, 2010. © 2010 Wiley-Liss, Inc.
    Preview · Article · Apr 2010 · Human Mutation
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    ABSTRACT: Waardenburg syndrome (WS) is a rare disorder characterized by distinctive facial features, pigment disturbances, and sensorineural deafness. There are four WS subtypes. WS1 is mostly caused by PAX3 mutations, while MITF, SNAI2, and SOX10 mutations are associated with WS2. More than 100 different disease-causing mutations have been reported in many ethnic groups, but the data from Chinese patients with WS remains poor. Herein we report 18 patients from 15 Chinese WS families, in which five cases were diagnosed as WS1 and the remaining as WS2. Clinical evaluation revealed intense phenotypic variability in Chinese WS patients. Heterochromia iridis and sensorineural hearing loss were the most frequent features (100% and 88.9%, respectively) of the two subtypes. Many brown freckles on normal skin could be a special subtype of cutaneous pigment disturbances in Chinese WS patients. PAX3, MITF, SNAI2, and SOX10 genes mutations were screened for in all the patients. A total of nine mutations in 11 families were identified and seven of them were novel. The SOX10 mutations in WS2 were first discovered in the Chinese population, with an estimated frequency similar to that of MITF mutations, implying SOX10 is an important pathogenic gene in Chinese WS2 cases and should be considered for first-step analysis in WS2, as well as MITF.
    No preview · Article · Jun 2010 · Biochemical and Biophysical Research Communications
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