[Clinical classification and genetic mutation study of two pedigrees with type II Waardenburg syndrome].

OBJECTIVE: To explore the molecular etiology of two pedigrees affected with type II Waardenburg syndrome (WS2) and to provide genetic diagnosis and counseling. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Shah-Waardenburg syndrome.

Shah-Waardenburg syndrome (SWS) is a neurocristopathy and is characterized by Hirschsprung's disease (HD), deafness, and depigmentation of hairs, skin, and iris. Is a very rare congenital disorder with variable clinical expression. This report describes a 4-day-old male newborn with Waardenburg's syndrome associated with aganglionosis of the colon and terminal ileum, and review the relevant literature for draws attention to the causal relationship between these two entities.

[Hereditary hypomelanocytoses: the role of PAX3, SOX10, MITF, SNAI2, KIT, EDN3 and EDNRB genes]. / Hipomelanocytozy dziedziczne: rola genów PAX3, SOX10, MITF, SNAI2, KIT, EDN3 i EDNRB.

Hypo- and hyperpigmentation disorders are the most severe dermatological diseases observed in patients from all over the world. These disorders can be divided into melanoses connected with disorders of melanocyte function and melanocytoses connected with melanocyte development. The article presents some hereditary hypomelanocytoses, which are caused by abnormal melanoblast development, migration and proliferation as well as by abnormal melanocyte viability and proliferation. These disorders are represented by Waardenburg syndrome, piebaldism and Tietz syndrome, and are caused by different mutations of various or the same genes. The types of mutations comprise missense and nonsense mutations, frameshifts (in-frame insertions or deletions), truncating variations, splice alterations and non-stop mutations. It has been demonstrated that mutations of the same gene may cause different hypopigmentation syndromes that may have similar phenotypes. For example, mutations of the MITF gene cause Waardenburg syndrome type 2A as well as Tietz syndrome. It has also been demonstrated that mutations of different genes may cause an identical syndrome. For example, mutations of MITF, SNAI2 and SOX10 genes are observed in Waardenburg syndrome type II and mutations of EDNRB, EDN3 and SOX10 genes are responsible for Waardenburg syndrome type IV. In turn, mutation of the KIT gene and/or heterozygous deletion of the SNAI2 gene result in piebaldism disease. The knowledge of the exact mechanisms of pigmentary disorders may be useful in the development of new therapeutic approaches to their treatment.

Síndrome de Waardenburg: clasificación clínica de una familia / Waardenburg's syndrome: clinical classification of a family

El síndrome de Waardenburg (SW) es una entidad infrecuente, hereditaria, que cursa con cierto grado de discapacidad cuando aparece la hipoacusia neurosensorial y su cuadro clínico no está completamente definido. El objetivo fue describir las características clínicas de una familia afectada con el síndrome y las variantes encontradas. Se aplicó un estudio de casos, observacional, transversal y descriptivo. Se confeccionó una base de datos automatizada. Las variables utilizadas fueron los signos clínicos, incluyendo la clasificación de la hipoacusia. Se utilizaron medidas de frecuencia: absolutas y relativas porcentuales, y se empleó la prueba de X2 al 95 por ciento de certeza. De los signos clásicos el 100 por ciento mostró distopia cantorum, el resto apareció con variabilidad. Se observaron signos no descritos anteriormente, entre los cuales destacó el dorso nasal recto (65,4 por ciento). Se detectó hallux valgus en 4 de los individuos, lo que permitió clasificar a los individuos en 19 del tipo I, y los 7 restantes en la subvariante 1 del tipo III. Las alteraciones óseas encontradas en individuos con SW permiten clasificarlos como portadores de la subvariante III-1, no descrita previamente(AU)

Waardenburg Syndrome (SW) is a rare inherited disorder characterized by varying degrees of disability, when sensorineural hearing loss appear and its clinical chart is not definitely complete. The objective was to describe the clinical characteristics of a family suffering from this entity and the variables found. Observational, cross-sectional and descriptive case studies were carried out. An automated database was created, using the variables of clinical signs, including the classification of hypoacusis. Measures of frequency were employed: absolute and relative percentages as well as X2 test with 95 per cent of confidence. Out of the classical signs 100 per cent showed dystopia canthorum, the rest appeared with variability. Observing signs not previously described, among them, a marked straight-nasal dorsum (65,4 per cent). Hallux valgus was detected in 4 of the subjects; which allowed classifying them into: 19 of Type-I and the rest (7) in the sub-variant-1 of Type-III. The osseous alterations found in subjects suffering from SW allowed classifying them as sub-variant III-1 carriers, not previously described(AU)

[Waardenburg Syndrome: a review of literature and case reports]. / Revisione critica della letteratura sulla Sindrome di Waardenburg e presentazione di due casi clinici.

Waadernburg syndrome (WS) is an autosomal dominant disease clinically and genetically heterogeneous. It is characterized by non-progressive sensorineuronal hearing loss of variable degree and anomalous pigmentation (of the eyes, skin and stria vascularis of cochlear duct) caused by melanocytes absence. The syndrome is caused by mutations in genes that regulate the melanocytes differentiation from the neural crest during embriogenetic development. This study will review the literature on WS and explain more in detail the ocular findings in WS, while reporting new findings on two newly diagnosed cases.

Identification and functional analysis of SOX10 missense mutations in different subtypes of Waardenburg syndrome.

Waardenburg syndrome (WS) is a rare disorder characterized by pigmentation defects and sensorineural deafness, classified into four clinical subtypes, WS1-S4. Whereas the absence of additional features characterizes WS2, association with Hirschsprung disease defines WS4. WS is genetically heterogeneous, with six genes already identified, including SOX10. About 50 heterozygous SOX10 mutations have been described in patients presenting with WS2 or WS4, with or without myelination defects of the peripheral and central nervous system (PCWH, Peripheral demyelinating neuropathy-Central dysmyelinating leukodystrophy-Waardenburg syndrome-Hirschsprung disease, or PCW, PCWH without HD). The majority are truncating mutations that most often remove the main functional domains of the protein. Only three missense mutations have been thus far reported. In the present study, novel SOX10 missense mutations were found in 11 patients and were examined for effects on SOX10 characteristics and functions. The mutations were associated with various phenotypes, ranging from WS2 to PCWH. All tested mutations were found to be deleterious. Some mutants presented with partial cytoplasmic redistribution, some lost their DNA-binding and/or transactivation capabilities on various tissue-specific target genes. Intriguingly, several mutants were redistributed in nuclear foci. Whether this phenomenon is a cause or a consequence of mutation-associated pathogenicity remains to be determined, but this observation could help to identify new SOX10 modes of action.

PAX3 mutations and clinical characteristics in Chinese patients with Waardenburg syndrome type 1.

PURPOSE: To detect paired box gene 3 (PAX3) mutations and associated phenotypes in Chinese patients with Waardenburg syndrome type 1 (WS1). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Review and update of mutations causing Waardenburg syndrome.

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.

Clinical variability of Waardenburg-Shah syndrome in patients with proximal 13q deletion syndrome including the endothelin-B receptor locus.

Waardenburg-Shah syndrome (Waardenburg syndrome type IV-WS4) is an auditory-pigmentary disorder that combines clinical features of pigmentary abnormalities of the skin, hair and irides, sensorineural hearing loss, and Hirschsprung disease (HSCR). Mutations in the endothelin-B receptor (EDNRB) gene on 13q22 have been found to cause this syndrome. Mutations in both alleles cause the full phenotype, while heterozygous mutations cause isolated HSCR or HSCR with minor pigmentary anomalies and/or sensorineural deafness. We investigated the status of the EDNRB gene, by FISH analysis, in three patients with de novo proximal 13q deletions detected at cytogenetic analysis and examined the clinical variability of WS4 among these patients. Chromosome 13q was screened with locus specific FISH probes and breakpoints were determined at 13q22.1q31.3 in Patients 1 and 3, and at 13q21.1q31.3 in Patient 2. An EDNRB specific FISH probe was deleted in all three patients. All patients had common facial features seen in proximal 13q deletion syndrome and mild mental retardation. However, findings related to WS4 were variable; Patient 1 had hypopigmentation of the irides and HSCR, Patient 2 had prominent bicolored irides and mild bilateral hearing loss, and Patient 3 had only mild unilateral hearing loss. These data contribute new insights into the pathogenesis of WS4.

Sensorineural deafness, distinctive facial features, and abnormal cranial bones: a new variant of Waardenburg syndrome?

The Waardenburg syndromes (WS) account for approximately 2% of congenital sensorineural deafness. This heterogeneous group of diseases currently can be categorized into four major subtypes (WS types 1-4) on the basis of characteristic clinical features. Multiple genes have been implicated in WS, and mutations in some genes can cause more than one WS subtype. In addition to eye, hair, and skin pigmentary abnormalities, dystopia canthorum and broad nasal bridge are seen in WS type 1. Mutations in the PAX3 gene are responsible for the condition in the majority of these patients. In addition, mutations in PAX3 have been found in WS type 3 that is distinguished by musculoskeletal abnormalities, and in a family with a rare subtype of WS, craniofacial-deafness-hand syndrome (CDHS), characterized by dysmorphic facial features, hand abnormalities, and absent or hypoplastic nasal and wrist bones. Here we describe a woman who shares some, but not all features of WS type 3 and CDHS, and who also has abnormal cranial bones. All sinuses were hypoplastic, and the cochlea were small. No sequence alteration in PAX3 was found. These observations broaden the clinical range of WS and suggest there may be genetic heterogeneity even within the CDHS subtype.

Deletions at the SOX10 gene locus cause Waardenburg syndrome types 2 and 4.

Waardenburg syndrome (WS) is an auditory-pigmentary disorder that exhibits varying combinations of sensorineural hearing loss and abnormal pigmentation of the hair and skin. Depending on additional symptoms, WS is classified into four subtypes, WS1-WS4. Absence of additional features characterizes WS2. The association of facial dysmorphic features defines WS1 and WS3, whereas the association with Hirschsprung disease (aganglionic megacolon) characterizes WS4, also called "Waardenburg-Hirschsprung disease." Mutations within the genes MITF and SNAI2 have been identified in WS2, whereas mutations of EDN3, EDNRB, and SOX10 have been observed in patients with WS4. However, not all cases are explained at the molecular level, which raises the possibility that other genes are involved or that some mutations within the known genes are not detected by commonly used genotyping methods. We used a combination of semiquantitative fluorescent multiplex polymerase chain reaction and fluorescent in situ hybridization to search for SOX10 heterozygous deletions. We describe the first characterization of SOX10 deletions in patients presenting with WS4. We also found SOX10 deletions in WS2 cases, making SOX10 a new gene of WS2. Interestingly, neurological phenotypes reminiscent of that observed in WS4 (PCWH syndrome [peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, WS, and Hirschsprung disease]) were observed in some WS2-affected patients with SOX10 deletions. This study further characterizes the molecular complexity and the close relationship that links the different subtypes of WS.

Waardenburg syndrome.

Waardenburg syndrome is a rare inherited and genetically heterogenous disorder of neural crest cell development. Four distinct subtypes showing marked interfamilial and intrafamilial variability have been described. We report a girl showing constellation of congenital hearing impairment with 110 dB and 105 dB loss in right and left ear respectively, hypoplastic blue iridis, white forelock, dystopia canthorum and broad nasal root. Other affected relatives of the family, with variable features of the syndrome, have been depicted in the pedigree.

[Waardenburg syndrome. A heterogenic disorder with variable penetrance]. / Waardenburg-Syndrom. Eine heterogene Erkrankung mit variabler Penetranz.

BACKGROUND: Waardenburg syndrome (WS) is an autosomal dominant disorder characterised by pigmentary anomalies of the skin, hairs, eyes and various defects of other neural crest derived tissues. It accounts for over 2% of congenital hearing impairment. At least four types are recognized on the basis of clinical and genetic criteria. PATIENTS AND METHODS: Based on a screening of congenitally hearing impaired children, 12 families with WS type II were detected. Of special interest was the phenotype of these families, in particular the reduced penetrance of hearing impairment within the families. RESULTS AND CONCLUSION: In all cases a high variability of the disease phenotype was detected and the penetrance of the clinical traits varied accordingly. Therefore, it is not possible to predict the clinical phenotype even in a single family. Based on these studies, we plan to identify the pathogenetic cause of the disease in order to perform a detailed genotype/phenotype analysis.

Mouse models for four types of Waardenburg syndrome.

Waardenburg syndrome (WS) is an auditory-pigmentary syndrome caused by a deficiency of melanocytes and other neural crest-derived cells. Depending on a variety of symptoms associated with the auditory-pigmentary symptoms, WS is classified into four types: WS type 1 (WS1), WS2, WS3, and WS4. Six genes contributing to this syndrome--PAX3, SOX10, MITF, SLUG, EDN3 and EDNRB--have been cloned so far, all of them necessary for normal development of melanocytes. Mutant mice with coat color anomalies were helpful in identifying these genes, although the phenotypes of these mice did not necessarily perfectly match those of the four types of WS. Here we describe mice with mutations of murine homologs of WS genes and verify their suitability as models for WS with special interest in the cochlear disorder. The mice include splotch (Sp), microphthalmia (mi), Slugh-/-, WS4, JF1, lethal-spotting (ls), and Dominant megacolon (Dom). The influence of genetic background on the phenotypes of mice mutated in homologs of WS genes is also addressed. Finally, possible interactions among the six WS gene products are discussed.