SOX10 Mutations Research Articles

Clinical and mutation analysis of 51 probands with anophthalmia and/or severe microphthalmia from a single center

Clinical evaluation and mutation analysis was performed in 51 consecutive probands with severe eye malformations – anophthalmia and/or severe microphthalmia – seen in a single specialist ophthalmology center. The mutation analysis consisted of bidirectional sequencing of the coding regions of SOX2, OTX2, PAX6 (paired domain), STRA6, BMP4, SMOC1, FOXE3, and RAX, and genome-wide array-based copy number assessment. Fifteen (29.4%) of the 51 probands had likely causative mutations affecting SOX2 (9/51), OTX2 (5/51), and STRA6 (1/51). Of the cases with bilateral anophthalmia, 9/12 (75%) were found to be mutation positive. Three of these mutations were large genomic deletions encompassing SOX2 (one case) or OTX2 (two cases). Familial inheritance of three intragenic, plausibly pathogenic, and heterozygous mutations was observed. An unaffected carrier parent of an affected child with an identified OTX2 mutation confirmed the previously reported nonpenetrance for this disorder. Two families with SOX2 mutations demonstrated a parent and child both with significant but highly variable eye malformations. Heterozygous loss-of-function mutations in SOX2 and OTX2 are the most common genetic pathology associated with severe eye malformations and bi-allelic loss-of-function in STRA6 is confirmed as an emerging cause of nonsyndromal eye malformations.

SOX2 maintains the quiescent progenitor cell state of postnatal retinal Müller glia

Within discrete regions of the developing mammalian central nervous system, small subsets of glia become specialized to function as neural stem cells. As a result of their self-renewal and neurogenic capacity, these cells later serve to replenish neurons and glia during persistent or injury-induced adult neurogenesis. SOX2, an HMG box transcription factor, plays an essential role in the maintenance of both embryonic and adult neural progenitors. It is unclear, however, which biological mechanisms regulated by SOX2 are required for neural stem cell maintenance. In this study, we address this question through genetic analysis of SOX2 function in differentiating postnatal Müller glia, a cell type that maintains neurogenic capacity in the adult retina. By utilizing molecular analysis and real-time imaging, we show that two progenitor characteristics of nascent Müller glia - their radial morphology and cell cycle quiescence - are disrupted following conditional genetic ablation of Sox2 in the mouse postnatal retina, leading to Müller cell depletion and retinal degeneration. Moreover, we demonstrate that genetic induction of the Notch signaling pathway restores Müller glial cell identity to Sox2 mutant cells, but does not secure their quiescent state. Collectively, these results uncouple the roles of SOX2 and the Notch signaling pathway in the postnatal retina, and uncover a novel role for SOX2 in preventing the depletion of postnatal Müller glia through terminal cell division.

Spectrum of Temporal Bone Abnormalities in Patients with Waardenburg Syndrome andSOX10Mutations

Waardenburg syndrome, characterized by deafness and pigmentation abnormalities, is clinically and genetically heterogeneous, consisting of 4 distinct subtypes and involving several genes. SOX10 mutations have been found both in types 2 and 4 Waardenburg syndrome and neurologic variants. The purpose of this study was to evaluate both the full spectrum and relative frequencies of inner ear malformations in these patients. Fifteen patients with Waardenburg syndrome and different SOX10 mutations were studied retrospectively. Imaging was performed between February 2000 and March 2010 for cochlear implant work-up, diagnosis of hearing loss, and/or evaluation of neurologic impairment. Eleven patients had both CT and MR imaging examinations, 3 had MR imaging only, and 1 had CT only. Temporal bone abnormalities were bilateral. The most frequent pattern associated agenesis or hypoplasia of ≥1 semicircular canal, an enlarged vestibule, and a cochlea with a reduced size and occasionally an abnormal shape, but with normal partition in the 13/15 cases that could be analyzed. Three patients lacked a cochlear nerve, bilaterally in 2 patients. In addition, associated abnormalities were found when adequate MR imaging sequences were available: agenesis of the olfactory bulbs (7/8), hypoplastic or absent lacrimal glands (11/14), hypoplastic parotid glands (12/14), and white matter signal anomalies (7/13). In the appropriate clinical context, bilateral agenesis or hypoplasia of the semicircular canals or both, associated with an enlarged vestibule and a cochlear deformity, strongly suggests a diagnosis of Waardenburg syndrome linked to a SOX10 mutation.

The Comprehensive Genomic Characterization of All Commercially Available Multiple Myeloma Cell Lines.

AbstractAbstract 2920Human myeloma cell lines (HMCL) provide both a discovery and validation platform to improve our understanding of the molecular pathogenesis of multiple myeloma. We have completed a project to characterize the underlying genetics of all commercially available HMCL with a primary goal of identifying appropriate model systems for findings from large scale patient studies like the multiple myeloma genomics initiative (MMGI). We first purchased all 33 commercially available HMCL from DSMZ, JCRB, ECACC, and ATCC. Subsequently each HMCL was thawed and cultured under strict parameters, which yielded cells for analysis, by Agilent 400k CGH, whole exome sequencing (Agilent 70Mb Exon+UTR), and mRNA sequencing. The combination of these three assays provides a detailed map of the genetic complexity underlying this deadly disease.For variant discovery, alignment was done using BWA followed by indel realignment, quality recalibration and duplicate removal. High quality calls were identified from the intersection of variants called by both Samtools and GATK. This identified a median of 32691 high confidence variants per sample with upper and lower quartile values of 34307.75 and 32241.25, respectively. To identify likely somatic mutations, we removed variants found in the 1000 genomes project and the NHLBI Exome Sequencing project. In addition, we removed variants present in dbSNP unless these mutations were also present in the COSMIC database. After these filtering steps a median of 702 potential mutations remained. From these lists we identified a median of 209.5 non-synonymous variants per sample and in genes which are typically expressed in the cohort, a median of 91 variants were found. Overall, these steps identified 2678 variants in 1978 genes.The primary goal was to identify appropriate models for novel findings from studies like the MMGI. For instance we identified HMCL with mutations in FAM46C and DIS3 among others. Secondarily, we focused on attempting to identify potential oncogenes and tumor suppressors through the integration of our three data types and data from published studies (Chapman et al. and Walker et al.). To identify potential oncogenes we focused on mutations that occurred at the same position in the genome or altered the same amino acid at a minimum. This identified 23 genes; including expected genes like KRAS (n=11) and, NRAS (n=7) but it also identified potentially activating mutations in IKBKB, SOX2, KDM4C, CD81, OSBP, NOTCH2, WDR92 and UBR2. To identify potential tumor suppressors we focused on genes that are typically expressed, which showed bi-allelic inactivation in two or more samples by either a homozygous deletion event, a deletion plus mutation, or two independent mutations. This identified 116 genes; including expected genes like TP53, CDKN2C, RB1, BIRC2/3, TRAF3, KDM6A, CDKN1B, FAM46C, and DIS3. Outside of the expected genes we identified recurrent inactivation in ANKRD11, ATP6AP1, ATXN1, BCL2L11, CDK8, RNF7, STS, TSPAN7, and TBL1XR1.These studies have highlighted the value in studying HMCL as most novel genes reported from recent studies were independently identified in this small cohort of samples. This is in large part because HMCL provide an unlimited DNA and RNA resource that allowed for multiple independent assays to be performed on each sample. Ultimately this study will provide the myeloma community with a detailed resource from which they can acquire appropriate model systems for their research goals from the various cell line repositories around the world. Disclosures:Keats:Tgen: Employment.

Septo-optic dysplasia plus bilateral perisylvian polymicrogyria: a case report

Septo-optic dysplasia (SOD) is a rare and highly heterogeneous disorder that is usually characterised by any combination of the classic triad of optic nerve hypoplasia, midline neuroradiological abnormalities and pituitary hypoplasia [1]. Furthermore back in 2000, Miller et al. [2] divided SOD into two subgroups, isolated SOD characterised by the absence of the septum pellucidum, hypoplasia of the optic nerves, and diffuse white matter hypoplasia and SOD plus characterised by the association with diverse brain malformations. Although SOD has been observed with several cortical abnormalities, the association with congenital bilateral perisylvian polymicrogyria has been reported only by few authors and exclusively in patients with refractory epilepsy, oropharyngoglossal dysfunction or delayed developmental milestones [1, 2]. Here, we describe a 22-year-old Romanian man was referred to our neurology clinic because of characterization of very rare complex partial seizures. He was born by caesarean section after a normal pregnancy at 38 weeks of gestation from a nonconsanguineous marriage. No problems have been encountered in the pre and perinatal period. There is no family history of epilepsy or neurological disorders. After the age of two it was noted that he had left hemiparesis. He began to have sporadic complex partialtype seizures described as staring and rare secondary generalization at 21 years of age, easily controlled with levetiracetam. His cranial nerves were intact and the neuroophthalmologic examination showed only a pale optic disk. He had no mental or cognitive impairment. Routine laboratory analyses were normal. He suffered of isolated high levels of prolactin. A cytogenetic analysis of his peripheral blood indicated a normal 46, XY karyotype. Screening for HESX1 and SOX2 mutations, rarely reported in patients with SOD, showed normal results [2]. As well TUBB2B mutation [3] often associated with neuronal migration was negative and the array-CGH analysis ruled out chromosomal re-arrangements. The electrocardiogram was normal. The patient underwent standard and sleep-deprived electroencephalography as well as a brain magnetic resonance imaging (MRI) (3-Tesla GE SIGNA NVI at the Neuroimaging research Unit, Institute of Neurologic Science of National Research Council, Germaneto, Catanzaro), based on our protocol routinely used for patients with epilepsy extensively described elsewhere [4, 5]. Electroencephalographic examinations showed only sporadic diffuse slowwaves without frank epileptiform discharges. Cranial MRI displayed absence of the septum pellucidum and a bilateral perisylvian polymicrogyria more pronounced over the left hemisphere (Fig. 1a, b). The current case represents an isolated report of a patient with SOD plus bilateral perisylvian polymicrogyria presenting only with very mild epilepsy. It might enlarge the heterogeneous spectrum of mild form of SOD plus although our patient suffered only from drug-responsive A. Labate A. Quattrone Institute of Neurology, University Magna Graecia, Catanzaro, Italy

Pediatric case report: Clinical profile of a patient with PCWH with p.Q377X nonsense mutation in the SOX10 gene

We report the case of a Japanese patient with PCWH, a neurological variant of Waardenburg type 4. Direct sequencing of the genomic DNA obtained from peripheral leukocytes revealed the p.Q377X nonsense mutation in the SOX10 gene. The patient had mottled hypopigmented macules on the trunk since birth; such macules have not been described previously. The so-called "white forelock", a triangular or diamond shaped leukoderma on the forehead, was absent. We also reviewed and summarized the outcomes of 23 patients with Waardenburg syndrome type 4, PCWH and Yemenite deaf-blind hypopigmentation syndrome, in which SOX10 mutations were identified. Among them, 17 cases were reported to have hypopigmented skin macule(s). The five patients who had the white forelock had PCWH with severe neurological complications. Paradoxically, two cases had hyperpigmented spots. Heterochromia of the iris was reported in four patients.

Comprehensive molecular characterization of human colon and rectal cancer.

To characterize somatic alterations in colorectal carcinoma, we conducted a genome-scale analysis of 276 samples, analysing exome sequence, DNA copy number, promoter methylation and messenger RNA and microRNA expression. A subset of these samples (97) underwent low-depth-of-coverage whole-genome sequencing. In total, 16% of colorectal carcinomas were found to be hypermutated: three-quarters of these had the expected high microsatellite instability, usually with hypermethylation and MLH1 silencing, and one-quarter had somatic mismatch-repair gene and polymerase ε (POLE) mutations. Excluding the hypermutated cancers, colon and rectum cancers were found to have considerably similar patterns of genomic alteration. Twenty-four genes were significantly mutated, and in addition to the expected APC, TP53, SMAD4, PIK3CA and KRAS mutations, we found frequent mutations in ARID1A, SOX9 and FAM123B. Recurrent copy-number alterations include potentially drug-targetable amplifications of ERBB2 and newly discovered amplification of IGF2. Recurrent chromosomal translocations include the fusion of NAV2 and WNT pathway member TCF7L1. Integrative analyses suggest new markers for aggressive colorectal carcinoma and an important role for MYC-directed transcriptional activation and repression.Supplementary informationThe online version of this article (doi:10.1038/nature11252) contains supplementary material, which is available to authorized users.

Genetic Overlap between Holoprosencephaly and Kallmann Syndrome

Patients with Kallmann syndrome (KS; congenital hypogonadotropic hypogonadism and decreased/absent sense of smell), septo-optic dysplasia (SOD), or holoprosencephaly (HPE) reportedly have midline defects. In this study, we investigate a genetic overlap between KS, SOD, and HPE. Nineteen subjects (18 males, 1 female) with KS and without mutations in the known KS genes were screened for mutations in SOX2, SHH, SIX3,TGIF1,TDGF1,FOXH1,GLI2, and GLI3. One male carried 2 heterozygous missense changes, one in SIX3 (c.428G>A, p.G143D) and the other in GLI2 (c.2509G>A, p.E837K). Both of these genes have been implicated in the etiology of HPE and neither of these changes were present in 200 control subjects. Other variants found among the subjects were known polymorphisms. KS and HPE may display a genetic overlap. The involvement of genes implicated in the etiology of midline defects in patients with KS warrants further studies.

Emx2 is a dose-dependent negative regulator of Sox2 telencephalic enhancers

The transcription factor Sox2 is essential for neural stem cells (NSC) maintenance in the hippocampus and in vitro. The transcription factor Emx2 is also critical for hippocampal development and NSC self-renewal. Searching for ‘modifier’ genes affecting the Sox2 deficiency phenotype in mouse, we observed that loss of one Emx2 allele substantially increased the telencephalic β-geo (LacZ) expression of a transgene driven by the 5′ or 3′ Sox2 enhancer. Reciprocally, Emx2 overexpression in NSC cultures inhibited the activity of the same transgene. In vivo, loss of one Emx2 allele increased Sox2 levels in the medial telencephalic wall, including the hippocampal primordium. In hypomorphic Sox2 mutants, retaining a single ‘weak’ Sox2 allele, Emx2 deficiency substantially rescued hippocampal radial glia stem cells and neurogenesis, indicating that Emx2 functionally interacts with Sox2 at the stem cell level. Electrophoresis mobility shift assays and transfection indicated that Emx2 represses the activities of both Sox2 enhancers. Emx2 bound to overlapping Emx2/POU-binding sites, preventing binding of the POU transcriptional activator Brn2. Additionally, Emx2 directly interacted with Brn2 without binding to DNA. These data imply that Emx2 may perform part of its functions by negatively modulating Sox2 in specific brain areas, thus controlling important aspects of NSC function in development.

Disruption of SoxB1-Dependent Sonic hedgehog Expression in the Hypothalamus Causes Septo-optic Dysplasia

Septo-optic dysplasia (SOD) is a congenital brain anomaly that results in pituitary, optic nerve, and midline forebrain defects. The etiology of SOD is poorly understood, with the majority of cases being sporadic. In rare instances, SOD is caused by mutations in Sox2, Sox3, or Hesx1, but how this manifests in disease is not entirely certain. We demonstrate here that mouse embryos lacking Sonic hedgehog (Shh) in the prospective hypothalamus exhibit key features of SOD, including pituitary hypoplasia and absence of the optic disc. The hypothalamic source of Shh is required to maintain gene expression boundaries along the anteroposterior and mediolateral neural axes that are important for proper pituitary and eye development, respectively. We further reveal that Sox2 and Sox3 are dose-dependent regulators of Shh transcription that directly bind and activate a long-range Shh forebrain enhancer. These data indicate that reduced levels of Shh expression in the hypothalamus cause SOD.

Regulation of Human Chondrocyte Function through Direct Inhibition of Cartilage Master Regulator SOX9 by MicroRNA-145 (miRNA-145)

Articular cartilage enables weight bearing and near friction-free movement in the joints. Critical to its function is the production of a specialized, mechanocompetent extracellular matrix controlled by master regulator transcription factor SOX9. Mutations in SOX9 cause campomelic dysplasia, a haploinsufficiency disorder resulting in severe skeletal defects and dwarfism. Although much is understood about how SOX9 regulates cartilage matrix synthesis and hence joint function, how this master regulator is itself regulated remains largely unknown. Here we identify a specific microRNA, miR-145, as a direct regulator of SOX9 in normal healthy human articular chondrocytes. We show that miR-145 directly represses SOX9 expression in human cells through a unique binding site in its 3'-UTR not conserved in mice. Modulation of miR-145 induced profound changes in the human chondrocyte phenotype. Specifically, increased miR-145 levels cause greatly reduced expression of critical cartilage extracellular matrix genes (COL2A1 and aggrecan) and tissue-specific microRNAs (miR-675 and miR-140) and increased levels of the hypertrophic markers RUNX2 and MMP13, characteristic of changes occurring in osteoarthritis. We propose miR-145 as an important regulator of human chondrocyte function and a new target for cartilage repair.

Erratam to novel SOX2 mutations and genotype‐phenotype correlation in anophthalmia and microphthalmia

Erratam to novel <i>SOX2</i> mutations and genotype‐phenotype correlation in anophthalmia and microphthalmia

A rare case of campomelic dysplasia: a case report

We report an uncommon case of campomelic dysplasia in a24-year-old patient nuliparva, pregnantin 38g.w. with breech presentation, admitted at the Specialized Obstetrics and Gynecology Hospital. The ultrasound Examination visualized Intrauterine Growth Retardation (IUGR) as well as severe angulation and rhizomelic Short ening of the femur and tibia. Those ultrasonography features suggested the presence of campomelic dysplasia. After aplanned Cesarian section, a female baby was delivered, weighing 2250 gr. Thepostnata lX ray was managed and the diagnosis was confirmed without other abnormallites. The genetic testing established normal karyo types of the parents and we suggested the new SOX9 mutation of the baby. No individual Feature is pathognomonic of this condition, however the most typical characteristic sign of campomelic Dysplasiais the marked anterior bowing of the long bones, particularly of the femur and tibia. Scripta Scientifica Medica 2011;43(2):73-75

Targeted 'Next-Generation' sequencing in anophthalmia and microphthalmia patients confirms SOX2, OTX2 and FOXE3 mutations

BackgroundAnophthalmia/microphthalmia (A/M) is caused by mutations in several different transcription factors, but mutations in each causative gene are relatively rare, emphasizing the need for a testing approach that screens multiple genes simultaneously. We used next-generation sequencing to screen 15 A/M patients for mutations in 9 pathogenic genes to evaluate this technology for screening in A/M.MethodsWe used a pooled sequencing design, together with custom single nucleotide polymorphism (SNP) calling software. We verified predicted sequence alterations using Sanger sequencing.ResultsWe verified three mutations - c.542delC in SOX2, resulting in p.Pro181Argfs*22, p.Glu105X in OTX2 and p.Cys240X in FOXE3. We found several novel sequence alterations and SNPs that were likely to be non-pathogenic - p.Glu42Lys in CRYBA4, p.Val201Met in FOXE3 and p.Asp291Asn in VSX2. Our analysis methodology gave one false positive result comprising a mutation in PAX6 (c.1268A > T, predicting p.X423LeuextX*15) that was not verified by Sanger sequencing. We also failed to detect one 20 base pair (bp) deletion and one 3 bp duplication in SOX2.ConclusionsOur results demonstrated the power of next-generation sequencing with pooled sample groups for the rapid screening of candidate genes for A/M as we were correctly able to identify disease-causing mutations. However, next-generation sequencing was less useful for small, intragenic deletions and duplications. We did not find mutations in 10/15 patients and conclude that there is a need for further gene discovery in A/M.

SOX2 haploinsufficiency is associated with slow progressing hypothalamo‐pituitary tumours

SOX2 is an early developmental transcription factor and marker of stem cells that has recently been implicated in the development of the pituitary gland. Heterozygous SOX2 mutations have been described in patients with hypopituitarism and severe ocular abnormalities. In the majority of published cases, the pituitary gland is either small or normal in size. Here, we report two unrelated patients with SOX2 haploinsufficiency (a heterozygous gene deletion and a novel c.143TC>AA/p.F48X mutation) who developed nonprogressive pituitary tumors of early onset, suggesting a congenital etiology. The truncating mutation resulted in significant loss of function and impaired nuclear localization of the mutant protein, in addition to a failure to repress β-catenin transcriptional activity in vitro. This is the first indication that SOX2 haploinsufficiency is implicated in the generation of pituitary tumors with distinct clinical characteristics, possibly mediated via its effects on the Wnt signaling pathway. 32:1376–1380, 2011. ©2011 Wiley Periodicals, Inc.

Sex-Reversed Acampomelic Campomelic Dysplasia With a Homozygous Deletion Mutation in SOX9 Gene

Campomelic dysplasia (CD) is a rare autosomal dominant skeletal malformation with or without sex reversal. About 10% of cases that present with milder skeletal features are referred to as acampomelic campomelic dysplasia (ACD). CD and ACD are caused by mutations in SOX9. We report a patient of homozygous SOX9 deletion with minimal skeletal anomaly and female external genitalia in the presence of a male karyotype. The mechanisms explaining the homozygous deletion include a de novo mutation followed by gene conversion, uniparental disomy, or somatic crossing over. Our report highlights the possibility of ACD in XY sex-reversed patients with minimal skeletal presentation.

Functional analysis of Waardenburg syndrome-associated PAX3 and SOX10 mutations: report of a dominant-negative SOX10 mutation in Waardenburg syndrome type II

Waardenburg syndrome (WS) is an auditory-pigmentary disorder resulting from melanocyte defects, with varying combinations of sensorineural hearing loss and abnormal pigmentation of the hair, skin, and inner ear. WS is classified into four subtypes (WS1-WS4) based on additional symptoms. PAX3 and SOX10 are two transcription factors that can activate the expression of microphthalmia-associated transcription factor (MITF), a critical transcription factor for melanocyte development. Mutations of PAX3 are associated with WS1 and WS3, while mutations of SOX10 cause WS2 and WS4. Recently, we identified some novel WS-associated mutations in PAX3 and SOX10 in a cohort of Chinese WS patients. Here, we further identified an E248fsX30 SOX10 mutation in a family of WS2. We analyzed the subcellular distribution, expression and in vitro activity of two PAX3 mutations (p.H80D, p.H186fsX5) and four SOX10 mutations (p.E248fsX30, p.G37fsX58, p.G38fsX69 and p.R43X). Except H80D PAX3, which retained partial activity, the other mutants were unable to activate MITF promoter. The H80D PAX3 and E248fsX30 SOX10 were localized in the nucleus as wild type (WT) proteins, whereas the other mutant proteins were distributed in both cytoplasm and nucleus. Furthermore, E248fsX30 SOX10 protein retained the DNA-binding activity and showed dominant-negative effect on WT SOX10. However, E248fsX30 SOX10 protein seems to decay faster than the WT one, which may underlie the mild WS2 phenotype caused by this mutation.

Association analysis of the SOX10 polymorphism with Hirschsprung disease in the Han Chinese population

Background Hirschsprung disease (HSCR, Online Mendelian Inheritance in Man 142623) is a typical developmental disorder of the enteric nervous system in which ganglion cells fail to innervate the lower gastrointestinal tract during embryonic development. SOX10 gene is involved in the normal development of the enteric nervous system. Heterozygous SOX10 mutations have been identified in patients with syndromic HSCR. However, no mutations have been reported to date to be associated to isolated HSCR patient. We thus sought to investigate whether mutations in the SOX10 are associated with isolated HSCR in the Chinese population. Methods Polymerase chain reaction amplification and direct sequencing were used to screen 4 exons of the SOX10 gene for mutations and polymorphisms in 104 patients with sporadic HSCR and 96 ethnically matched controls in Han Chinese populations. Results In this study, 4 single nucleotide polymorphisms (SNPs) were identified: SNP1: c.18C>T (GAC→GAT) in exon 2; SNP2: c.122G>T (GGC→GTC) in exon 2; SNP3: IVS2+10 (C→G) in intron 2; and SNP4: c.927T>C (CAT→CAC) in exon 4. SNP1 and SNP2 were novel described polymorphisms in the Chinese population. No SOX10 mutations were found in Han Chinese with isolated HSCR. Conclusions Our results revealed that there was no association between the 4 SNPs of the SOX10 gene and HSCR. This study showed that the SOX10 gene is unlikely to be a major HSCR gene in the Chinese Han population.

Campomelic Dysplasia: Airway Management in Two Patients and an Update on Clinical-Molecular Correlations in the Head and Neck

Campomelic dysplasia is a rare and historically lethal skeletal dysplasia with a variable but recognizable phenotype; it affects the long bones and is associated with a variety of head and neck anomalies. Mutations in or around the SOX9 gene have been identified as the molecular origin in most patients. We briefly present 2 children who meet the diagnostic criteria for campomelic dysplasia to illustrate the various clinical manifestations. Many patients with campomelic dysplasia have airway obstruction at multiple levels. We describe our approach to managing the airway in these patients, and review recent advances in understanding how SOX9 mutations lead to the spectrum of abnormalities seen in the head and neck.

Identification and functional analysis ofSOX10missense 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.