DiagnosisClinical DiagnosisDiagnostic criteria for Waardenburg syndrome type I (WS1) have been proposed by the Waardenburg Consortium [Farrer et al 1992]. An individual must have two major criteria or one major plus two minor criteria to be considered affected. Major CriteriaCongenital sensorineural hearing lossWhite forelock, hair hypopigmentationPigmentation abnormality of the iris:Complete heterochromia iridum (irides of different color)Partial/segmental heterochromia (two different colors in same iris, typically brown and blue)Hypoplastic blue irides, or brilliant blue iridesDystopia canthorum, W index >1.95 *Affected first-degree relativeMinor CriteriaSkin hypopigmentation (congenital leukoderma)Synophrys/medial eyebrow flareBroad/high nasal root, prominent columellaHypoplastic alae nasiPremature gray hair (age <30 years)* W index: The measurements necessary to calculate the W index (in mm) are as follows: inner canthal distance (a), interpupillary distance (b), and outer canthal distance (c).Calculate X = (2a – (0.2119c + 3.909))/c
Calculate Y = (2a – (0.2479b + 3.909))/b
Calculate W = X + Y + a/bA W index result greater than 1.95 is abnormal. Previously, a W index of greater than 2.07 was necessary to diagnose WS1 in an individual meeting all of the other diagnostic criteria. With molecular analysis, a family previously classified clinically as having WS2 based on the W index was found to have a PAX3 mutation and was reclassified as having WS1 [Tassabehji et al 1993]. Hence, the W index threshold was reduced to its current value of greater than 1.95.Molecular Genetic TestingGene. PAX3 is the only gene in which mutations are known to cause Waardenburg syndrome type I (WS1).Clinical testingSequence analysis. More than 90% of individuals who meet the clinical diagnostic criteria for Waardenburg syndrome type I have identifiable mutations in PAX3 [Pingault et al 2010; Milunsky 2011, unpublished data]. Deletion/duplication analysis*. Partial and whole PAX3 deletions may account for approximately 6% of cases [Milunsky et al 2007]. No duplications have been reported.
*Testing that detects deletions/duplications not readily detectable by sequence analysis of genomic DNA; a variety of methods including quantitative PCR, real-time PCR, multiplex ligation-dependent probe amplification (MLPA), or array GH may be used. Table 1. Summary of Molecular Genetic Testing Used in Waardenburg Syndrome Type IView in own windowGene SymbolTest MethodMutations DetectedMutation Detection Frequency by Test Method ^{1Test Availability PAX3Sequence analysisSequence variants 2>90%ClinicalDeletion / duplication analysis 3Exonic or whole-gene deletions~6%1. The ability of the test method used to detect a mutation that is present in the indicated gene2. Mutations detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site mutations; typically, exonic or whole-gene deletions/duplications are not detected.3. Testing that identifies deletions/duplications not readily detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA; a variety of methods including quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), or targeted chromosomal microarray analysis (gene/segment-specific) may be used. A full chromosomal microarray analysis that detects deletions/duplications across the genome may also include this gene/segment.Interpretation of test results. For issues to consider in interpretation of sequence analysis results, click here.Information on specific allelic variants may be available in Molecular Genetics (see Table A. Genes and Diseases and/or Pathologic allelic variants).Testing StrategyTo confirm/establishthe diagnosis in a probandPAX3 sequencing is performed first.Deletion testing is recommended for those individuals who meet the clinical diagnostic criteria for WS1 and have no detectable mutation by PAX3 sequencing.Predictive testing for at-risk asymptomatic family members for clarification of genetic status requires prior identification of the disease-causing mutation in the family.Prenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies require prior identification of the disease-causing mutation in the family.Genetically Related (Allelic) DisordersGermline PAX3 mutations also cause the following:Waardenburg syndrome type 3 (WS3) (Klein-Waardenburg syndrome), is characterized by a combination of typical WS1 features and hypoplasia or contractures of the limb muscles or joints, carpal bone fusion, or syndactyly [Hoth et al 1993]. In a consanguineous Turkish family, both parents who are heterozygous for the PAX3 Tyr90His mutation have WS1; their child who is homozygous for the Tyr90His mutation has WS3 [Wollnik et al 2003].Craniofacial-deafness-hand syndrome (CDHS) [OMIM 122880] is characterized by a flat facial profile, ocular hypertelorism, hypoplastic nose with slit-like nares, and sensorineural hearing loss. X-ray findings include a small maxilla, absent or small nasal bones, and ulnar deviation of the hands [Sommer & Bartholomew 2003]. Asher et al [1996] identified a missense mutation in PAX3 in individuals with this disorder. This disorder is apparently distinct from both WS1 and WS3. Gad et al [2008] reported a woman who shares some, but not all features of WS3 and CDHS, and who also has abnormal cranial bones (hypoplastic sinuses and small cochlea). Whereas no sequence alteration or whole-gene deletion of PAX3 was found, partial-gene deletions were not ruled out. The authors suggest genetic heterogeneity even within the CDHS subtype. Somatic PAX3 mutations have been observed in alveolar rhabdomyosarcoma. PAX3 can fuse with FKHR, this fusion creating a gain-of-function mechanism that results in alveolar rhabdomyosarcoma [Wang et al 2008]. Individuals with alveolar rhabdomyosarcoma resulting from this mechanism do not have WS.}

Natural HistoryThe phenotype of Waardenburg syndrome type I (WS1) is variable even within a family. Liu et al [1995] summarized the penetrance (percentage) of clinical features of WS1 (see Table 2) in 60 individuals with WS1 and 210 affected individuals reported elsewhere in the literature. Newton [2002] reviewed the clinical features of the Waardenburg syndromes and more recently, Tamayo et al [2008] discussed their screening program for Waardenburg syndrome in Colombia, detailing the percentage of each clinical manifestation. Similar percentages were documented compared to the Liu et al [1995] study. However, ascertainment bias was evident, as all 95 affected individuals had hearing loss and were among the institutionalized deaf population in Colombia. Table 2. Penetrance of Clinical Features of Waardenberg Syndrome Type IView in own windowClinical Finding% of Affected IndividualsSensorineural hearing loss47%-58%Heterochromic irides15%-31%Hypoplastic blue irides15%-18%White forelock43%-48%Early graying23%-38%Leukoderma22%-36%High nasal root52%-100%Medial eyebrow flare63%-73%Based on Liu et al [1995], Pardono et al [2003], Tamayo et al [2008]Hearing loss. The hearing loss in WS1 is congenital, typically non-progressive, either unilateral or bilateral, and of the sensorineural type. The most common type in WS1 is profound bilateral hearing loss (>100 dB). The laterality of the hearing loss is variable among and within families. Various temporal bone abnormalities have been identified in persons with WS1 and hearing loss [Madden et al 2003]. The temporal bone abnormalities include enlargement of the vestibular aqueduct and upper vestibule, narrowing of the internal auditory canal porus, and hypoplasia of the modiolus. Hair color. The classic white forelock is the most common hair pigmentation anomaly seen in WS. The white forelock may be present at birth, or appear later, typically in the teen years. The white forelock may become normally pigmented over time. The white forelock is typically in the midline but the patch of white hair may also be elsewhere. In evaluating an individual with suspected WS1 without a white forelock, the individual should be asked whether the hair has been dyed. Red and black forelocks have also been described. The majority of individuals with WS1 have either a white forelock or early graying of scalp hair before age 30 years [Farrer et al 1992].The hypopigmentation can also involve the eyebrows and eyelashes.Skin pigmentation. Congenital leukoderma (white skin patches) is frequently seen in WS1 on the face, trunk, or limbs. These areas of hypopigmentation frequently have hyperpigmented borders and may be associated with an adjacent white forelock.Occasional findings identified in multiple families (although too few to determine the percentage occurrence in this disorder): Cleft lip and palate Spina bifida [da-Silva 1991], a finding that is not surprising given that WS is considered a neurocristopathy with PAX3 being expressed in the neural crest: Kujat et al [2007] described the prenatal diagnosis of spina bifida in a WS1 family.Studies by Lu et al [2007] indicated that PAX3 SNPs were not strong risk factors for spina bifida [Kujat et al 2007]. Vestibular symptoms including vertigo, dizziness, and balance difficulties, even without hearing loss [Black et al 2001]Otopathology. The otopathology of an individual with WS1 and a PAX3 mutation has been described [Merchant et al 2001]. The findings are consistent with defective melanocyte migration or function resulting in defective development of the stria vascularis leading to sensorineural hearing loss.

Genotype-Phenotype CorrelationsPAX3. Genotype/phenotype correlations in PAX3 are not well established except for the Asn47His mutation in WS3 [Hoth et al 1993] and the Asn47Lys mutation described in craniofacial-deafness-hand syndrome [Asher et al 1996]. DeStefano et al [1998] found that the presence of pigmentary disturbances in individuals with WS1 correlated more with PAX3 mutations that delete the homeodomain than with missense mutations or deletions that include the paired domain. No genotype-phenotype correlation for the hearing loss in WS1 has been found.PAX3 partial/whole gene deletions. There appears to be no discernable difference in severity between whole-gene/partial-gene deletions and the clinical spectrum reported for PAX3 mutations [Milunsky et al 2007].

Differential DiagnosisWaardenburg syndrome type I (WS1) needs to be differentiated from other causes of congenital, non-progressive sensorineural hearing loss (see Deafness and Hereditary Hearing Loss Overview) and from other forms of Waardenburg syndrome.Waardenburg syndrome type II (WS2). WS1 is distinguished from WS2 by the presence in WS1 of lateral displacement of the inner canthi (dystopia canthorum). If the average W index across a family is less than 1.95, the diagnosis is WS2. Sensorineural hearing loss and heterochromia iridum are the two most characteristic features of WS2. Both are more common in WS2 than WS1. White forelock and leukoderma are both more common in WS1 than in WS2 (Table 3).MITF mutations [Tassabehji et al 1994, Chen et al 2008] have been described in 10%-20% of individuals with WS2. MITF mutations have also been identified in individuals with Tietz syndrome (deafness with uniform hypopigmentation) [Tassabehji et al 1995]. SOX10 point mutations [Iso et al 2008] and deletions [Bondurand et al 2007] have been described in about 15% of individuals with WS2. Chen et al [2010] indicated that SOX10 mutations had a similar frequency as MITF mutations in individuals with WS2 of Chinese ancestry. Zhang et al [2012] and Chaoui et al [2011] performed functional analysis of SOX10 mutations. A frameshift mutation showed a dominant-negative effect on wild type SOX10, leading to faster protein decay, possibly resulting in a milder WS2 phenotype [Zhang et al 2012].Table 3. Comparison of Clinical Features in WS1 and WS2View in own windowClinical Finding% of Affected IndividualsWS1WS2Sensorineural hearing loss47%-58%77%-80%Heterochromic irides15%-31%42%-54%Hypoplastic blue irides15%-18%3%-23%White forelock43%-48%16%-23%Early graying23%-38%14%-30%Leukoderma22%-36%5%-12%High nasal root52%-100%0%-14%Medial eyebrow flare63%-73%7%-12%Based on Liu et al [1995], Pardono et al [2003], Tamayo et al [2008]Waardenburg syndrome type 4 (WS4). Individuals having a rare combination of pigmentary abnormalities, hearing loss, and Hirschsprung disease have WS4 [Jan et al 2008] caused by mutations in either EDNRB, EDN3 [Ohtani et al 2006], or SOX10 [Bondurand et al 2007, Sznajer et al 2008]. Piebaldism. Piebaldism has some pigmentary features in common with Waardenburg syndrome. A white forelock is commonly seen along with absent pigmentation of the medial forehead and eyebrows. Absent pigmentation of the chest, abdomen, and limbs is also common. A characteristic feature is hyperpigmented borders surrounding the unpigmented areas. Heterochromia irides and sensorineural deafness is rarely described. This disorder has shown genetic heterogeneity with dominant mutations/whole gene deletions described involving the KIT proto-oncogene. SNAI2 has also been implicated in the etiology of some cases of piebaldism [Sánchez-Martín et al 2003]. Note to clinicians: For a patient-specific ‘simultaneous consult’ related to this disorder, go to , an interactive diagnostic decision support software tool that provides differential diagnoses based on patient findings (registration or institutional access required).

ManagementEvaluations Following Initial DiagnosisTo establish the extent of disease in an individual diagnosed with Waardenburg syndrome type I (WS1), no evaluations other than audiology assessment are necessary.Treatment of ManifestationsManagement of the hearing loss associated with WS1 depends on its severity (see Deafness and Hereditary Hearing Loss Overview).SurveillanceThe hearing loss in WS1 is typically non-progressive. Hence, repeating the audiogram would typically be unnecessary. Evaluation of Relatives at RiskIf the family-specific PAX3 mutation is known, molecular genetic testing of relatives at risk allows for early screening of those at risk for hearing loss.See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.Pregnancy ManagementFolic acid supplementation in pregnancy has been recommended for women at increased risk of having a child with WS1, given the possibly increased risk of neural tube defects in association with WS1 [Fleming & Copp 1998].Therapies Under InvestigationSearch ClinicalTrials.gov for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Molecular GeneticsInformation in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.Table A. Waardenburg Syndrome Type 1: Genes and DatabasesView in own windowGene SymbolChromosomal LocusProtein NameLocus SpecificHGMDPAX32q36​.1Paired box protein Pax-3Deafness Gene Mutation DatabasePAX3Data are compiled from the following standard references: gene symbol from HGNC; chromosomal locus, locus name, critical region, complementation group from OMIM; protein name from UniProt. For a description of databases (Locus Specific, HGMD) to which links are provided, click here.Table B. OMIM Entries for Waardenburg Syndrome Type 1 (View All in OMIM) View in own window 193500WAARDENBURG SYNDROME, TYPE 1; WS1 606597PAIRED BOX GENE 3; PAX3Molecular Genetic PathogenesisPAX3 is one of a family of nine human PAX genes coding for DNA-binding transcription factors that are expressed in the early embryo. The PAX genes are defined by the presence of a paired box (128 amino acid DNA-binding domain). In addition, PAX3 contains a homeobox [Birrane et al 2009].Normal allelic variants. PAX3 has ten exons [Read 2001], with the paired box in exons 2-4 and the homeobox in exons 5 and 6.Pathologic allelic variants. Mutations within the gene or deletion of the entire gene result in haploinsufficiency of PAX3. Mutations within PAX3 causing WS1 were first described in 1992 [Baldwin et al 1992, Tassabehji et al 1992]. Multiple abnormal allelic variants in different populations [Yang et al 2007, Chen et al 2010, Pingault et al 2010, Wang et al 2010] — including multiple mutations within PAX3 causing WS1, WS1 with spina bifida, WS3, and craniofacial-deafness-hand syndrome (CDHS) [OMIM 122880] — have been described.Normal gene product. Bondurand et al [2000] have shown that an interaction among PAX3, SOX10, and MITF in the regulation of melanocyte development affects a molecular pathway leading to the auditory-pigmentary abnormalities seen in WS. Given the marked variability in expression of phenotypic features among family members having the same mutation, the potential role of modifier genes may be significant. Sato-Jin et al [2008] further added to this research by demonstrating that EDNRB expression was dependent on MITF. In addition, they found that EDN directly stimulates the expression of melanocytic pigmentation in an MITF-dependent fashion.Abnormal gene product. The paired box protein Pax3 is an essential regulator of muscle and neural crest-derived cell types, including melanocytes. Analysis of PAX3 mutations observed in WS1 reveals distinct effects on the ability of PAX3 to regulate reporter genes fused to either the MITF or TRP-1 (tyrosinase-related protein 1) promoters [Corry & Underhill 2005]. Hence, Pax3 appears to be able to regulate target genes through alternate modes of DNA recognition that are dependent on the specific disease-causing mutations. Corry et al [2008] showed that the subnuclear localization and altered mobility of the PAX3 protein when the gene is mutated is a key determinant in its dysfunction. Birrane et al [2009] further demonstrated that certain PAX3 missense mutations could destabilize the folding of the PAX3 homeodomain, whereas others affect its interaction with DNA.