Microtia: epidemiology and genetics

[Bone anchored auricular prosthesis for patients with grade III microtia]

The aim of the study was to assess the effectivity of auricular prosthesis on intraosseous implants in patient with grade III microtia. The study included 7 patients (5 males and 2 females) aged 18 to 45 years with hemifacial microsomia and grade III microtia operated in Central Research Institute of Dentistry and Maxillofacial Surgery in 2013-2016. Number and position of intraosseous implants was determined by reverse planning based on CT representing hard and soft facial structures. Patients were followed-up for 6-36 months. Good esthetic results were obtained by minimally invasive surgical procedure and short post-op rehabilitation. However these results required meticulous virtual planning and manufacturing of surgical template. The described method promotes very fast medical and social rehabilitation of patients with severe microtia.

Preoperative assessment of stapes implantations of the vibrant SoundBridge for congenital aural atresia patients

OBJECTIVE

The objective of this study is to retrospectively analyze the imaging characteristics of patients with congenital aural atresia who underwent Vibrant Soundbridge implantation, and to investigate the importance of preoperative evaluation of vibroplasty.

MATERIALS AND METHODS

The study included 16 patients with bilateral congenital aural atresia aged 6-25 years (mean age, 14.7 years). All patients underwent Vibrant Soundbridge implantations.

RESULTS

Among the 16 patients, 15 successfully underwent stapes implantation. The average height of the stapes of these 15 patients was 2.93 mm, which was significantly different from that of the control group with normal hearing (p ≤ .001). The average distance between the tympanic segment of the facial nerve and the stapes was 1.41 mm in patients in whom the oval window was occluded by the displaced facial nerve. In the non-occluded group, the average distance was 2.00 mm. No significant difference was observed between the two groups (p = .08).

CONCLUSION

The distance between the facial nerve and stapes, as well as the height of the stapes, could be important predictors of successful stapes implantation of Vibrant Soundbridge.

Otologic and Audiology Concerns of Microtia Repair

Microtia is a congenital auricular deformity that commonly presents with associated congenital aural atresia. The most acute concern in these patients is concomitant hearing loss at birth. A team-based approach by plastic surgeons and otologists is necessary to address both the otologic and audiologic concerns of microtia and atresia. Hearing rehabilitation is imperative; yet it should not compromise the aesthetic components of reconstruction and vice versa. Here, the authors propose a framework to evaluate and manage patients with microtia and atresia with the goal of optimizing functional and cosmetic outcomes.

Chorda tympani nerve dysfunction associated with congenital microtia

CONCLUSION

This is the first report to investigate the correlation between ear anomalies related to the development of specific ear structures and chorda tympani dysfunction (CTD) in congenital microtia. CTD is not always consistent with the severity of the ear anomaly or the presence of facial nerve paralysis (FNP).

OBJECTIVES

To investigate the relationship between the severity of ear anomalies and CTD as well as FNP in congenital microtia.

METHODS

A retrospective assessment was performed for all patients with microtia over the period 2010-2016. All ears were graded based on the severity of ear deformity using the Jahrsdoerfer system, based on findings on computed tomography of the temporal bone. Electrogustometry (EGM) was performed to evaluate CTD.

RESULTS

The group included 110 male and 62 female patients. The right ear was the most commonly affected (right 106, left 47). Eighteen patients (10.5%) had abnormal EGM thresholds. The mean (± SD) Jahrsdoerfer scores in the without CTD and positive for CTD groups were 6.53 ± 0.32 and 7.06 ± 0.37, respectively. In terms of sub-total points, there was no significant correlation between anatomic structure and CTD. There was no significant correlation between CTD and the presence of FNP.

Cost analysis of microtia treatment in the Netherlands

INTRODUCTION

Ear reconstruction for microtia is a challenging procedure. Although analyzing esthetic outcome is crucial, there is a paucity of information with regard to financial aspects of microtia reconstruction. This study was conducted to analyze the costs associated with ear reconstruction with costal cartilage in patients with microtia.

METHODS

Ten consecutive children with autologous ear reconstruction of a unilateral microtia were included in this analysis. All patients had completed their treatment protocol for ear reconstruction. Direct costs (admission to hospital, diagnostics, and surgery) and indirect cost (travel expenses and absence from work) were obtained retrospectively.

RESULTS

The overall mean cumulative cost per patient was €14,753. Direct and indirect costs were €13,907 and €846, respectively. Hospital admission and surgery cover 55% and 32% of all the costs, respectively.

DISCUSSION

This study analyzes the costs for autologous ear reconstruction. Hospital admission and surgery are the most important factors of the total costs. Total costs could be decreased by possibly decreasing admission days and surgical time. These data can be used for choosing and developing future treatment strategies.

Differential expression of long noncoding RNAs in congenital microtia

OBJECTIVE

To analyse lncRNA expression profiles in microtia using bioinformatics analysis.

METHODS

We examined lncRNA expression profiles in residual ear cartilage and normal ear cartilage from individual congenital microtia patients.

RESULTS

The gene chips used in this study included 30586 lncRNAs and 26109 mRNA probes. Intotal, 180 lncRNAs with differential expression weredetected in the residual ear cartilage compared with the normal cartilage, including 74 up-regulated and 106down-regulated lncRNAs. Signalling pathway analysis highlighted glyceride metabolism, osteoclast differentiation, andtumour growth. The results of qRT-PCR analysis were consistent with those of themicroarray.

CONCLUSION

Differential expression of lncRNAs occurs in microtia. These lncRNAs and related signalling pathways may play an important role in the occurrence and development ofmicrotia.

Microtia Reconstruction

Microtia reconstruction is a challenging endeavor that has seen significant technique evolution. It is important to educate patients and their families to determine the best hearing rehabilitation and ear reconstructive options. Microtia is often associated with aural atresia, hearing loss, and craniofacial syndromes. Optimal care is provided by multiple disciplines, including a reconstructive surgeon, an otologic surgeon, an audiologist, and a craniofacial pediatrician. Microtia management includes observation, prosthetic ear, autologous cartilage reconstruction, or alloplastic implant placement. Hearing management options are observation, bone conduction sound processor, or atresiaplasty with and without hearing aids. Appropriate counseling should be done to manage expectations.

Health-Related Quality-of-Life Instruments for Pediatric Patients with Diverse Facial Deformities: A Systematic Literature Review

BACKGROUND

Treatment for patients with diverse craniofacial conditions is complex and long-term. Craniofacial conditions profoundly influence health-related quality of life, and patient- and parent-reported outcomes provide a critical and complementary perspective on the multidisciplinary treatment of patients. However, little is known regarding the health-related quality of life among children with diverse craniofacial conditions. The purpose of this study was to systematically review the literature regarding patient- and parent-reported outcomes measures for patients with diverse craniofacial conditions.

METHODS

Articles from the PubMed, PsychINFO, CINAHL, Embase/MEDLINE, Scopus, and Web of Science databases that used patient- and/or parent-reported outcome instruments in patients with diverse craniofacial conditions were reviewed. Diagnoses included were cleft lip and/or palate, craniosynostosis, microtia, craniofacial microsomia, facial vascular malformations, and congenital nevi across pediatric populations (0 to 22 years of age).

RESULTS

Six hundred ninety articles were identified, and 155 were selected for inclusion. One hundred twenty different health-related quality-of-life tools were used to analyze factors such as physical, psychological, or social function. Of these, the 10 most common psychometrically tested tools were identified in 59 studies. Five tools had both parent and patient versions. Two tools were developed and validated for patients with diverse craniofacial conditions, but neither was developed for nonadolescent children.

CONCLUSIONS

Many parent- and patient-reported instruments are used to measure varying health-related quality of life factors in this population, but no tool exists that was developed and psychometrically tested in different facial deformities that measures comprehensive health-related quality of life issues across all pediatric ages. This study will guide the development of new tools to measure the parent and patient health-related quality-of-life perspective in patients with diverse craniofacial conditions.

Chondrocytes from congenital microtia possess an inferior capacity for in vivo cartilage regeneration to healthy ear chondrocytes

The remnant auricular cartilage from microtia has become a valuable cell source for ear regeneration. It is important to clarify the issue of whether the genetically defective microtia chondrocytes could engineer cartilage tissue comparable to healthy ear chondrocytes. In the current study, the histology and cell yield of native microtia and normal ear cartilage were investigated, and the biological characteristics of derived chondrocytes examined, including proliferation, chondrogenic phenotype and cell migration. Furthermore, the in vivo cartilage-forming capacity of passaged microtia and normal auricular chondrocytes were systematically compared by seeding them onto polyglycolic acid/polylactic acid scaffold to generate tissue engineered cartilage in nude mice. Through histological examinations and quantitative analysis of glycosaminoglycan, Young's modulus, and the expression of cartilage-related genes, it was found that microtia chondrocytes had a slower dedifferentiation rate with the decreased expression of stemness-related genes, and weaker migration ability than normal ear chondrocytes, and the microtia chondrocytes-engineered cartilage was biochemically and biomechanically inferior to that constructed using normal ear chondrocytes. This study provides valuable information for the clinical application of the chondrocytes derived from congenital microtia to engineer cartilage. Copyright © 2016 John Wiley & Sons, Ltd.

A Review of Current Regenerative Medicine Strategies that Utilize Nanotechnology to Treat Cartilage Damage

BACKGROUND

Cartilage is an important tissue found in a variety of anatomical locations. Damage to cartilage is particularly detrimental, owing to its intrinsically poor healing capacity. Current reconstructive options for cartilage repair are limited, and alternative approaches are required. Biomaterial science and Tissue engineering are multidisciplinary areas of research that integrate biological and engineering principles for the purpose of restoring premorbid tissue function. Biomaterial science traditionally focuses on the replacement of diseased or damaged tissue with implants. Conversely, tissue engineering utilizes porous biomimetic scaffolds, containing cells and bioactive molecules, to regenerate functional tissue. However, both paradigms feature several disadvantages. Faced with the increasing clinical burden of cartilage defects, attention has shifted towards the incorporation of Nanotechnology into these areas of regenerative medicine.

METHODS

Searches were conducted on Pubmed using the terms "cartilage", "reconstruction", "nanotechnology", "nanomaterials", "tissue engineering" and "biomaterials". Abstracts were examined to identify articles of relevance, and further papers were obtained from the citations within.

RESULTS

The content of 96 articles was ultimately reviewed. The literature yielded no studies that have progressed beyond in vitro and in vivo experimentation. Several limitations to the use of nanomaterials to reconstruct damaged cartilage were identified in both the tissue engineering and biomaterial fields.

CONCLUSION

Nanomaterials have unique physicochemical properties that interact with biological systems in novel ways, potentially opening new avenues for the advancement of constructs used to repair cartilage. However, research into these technologies is in its infancy, and clinical translation remains elusive.

Optimizing cell sourcing for clinical translation of tissue engineered ears

Background . Currently, the major impediment to clinical translation of our previously described platform for the fabrication of high fidelity, patient-specific tissue engineered ears is the development of a clinically optimal cell sourcing strategy. A limited autologous auricular chondrocyte (AuC) supply in conjunction with rapid chondrocyte de-differentiation during in vitro expansion currently makes clinical translation more challenging. Mesenchymal stem cells (MSCs) offer significant promise due to their inherent chondrogenic potential, and large availability through minimally invasive procedures. Herein, we demonstrate the promise of AuC/MSC co-culture to fabricate elastic cartilage using 50% fewer AuC than standard approaches.

METHODS

Bovine auricular chondrocytes (bAuC) and bovine MSC (bMSC) were encapsulated within 10 mg ml^-1 type I collagen hydrogels in ratios of bAuC:bMSC 100:0, 50:50, and 0:100 at a density of 25 million cells ml^-1 hydrogel. One mm thick collagen sheet gels were fabricated, and thereafter, 8 mm diameter discs were extracted using a biopsy punch. Discs were implanted subcutaneously in the dorsa of nude mice (NU/NU) and harvested after 1 and 3 months.

RESULTS

Gross analysis of explanted discs revealed bAuC:bMSC co-culture discs maintained their size and shape, and exhibited native auricular cartilage-like elasticity after 1 and 3 months of implantation. Co-culture discs developed into auricular cartilage, with viable chondrocytes within lacunae, copious proteoglycan and elastic fiber deposition, and a distinct perichondrial layer. Biochemical analysis confirmed that co-culture discs deposited critical cartilage molecular components more readily than did both bAuC and bMSC discs after 1 and 3 months, and proteoglycan content significantly increased between 1 and 3 months.

CONCLUSION

We have successfully demonstrated an innovative cell sourcing strategy that facilitates our efforts to achieve clinical translation of our high fidelity, patient-specific ears for auricular reconstruction utilizing only half of the requisite auricular chondrocytes to fabricate mature elastic cartilage.

[Congenital cysts and fistulae in children]

Cysts and fistulae of the face and neck in children are formed before birth and correspond to the persistence of embryonic remnants that occur due to coalescence defects of embryonic buds or due to epidermal inclusion. They represent the most common pathological malformation of the face and neck. They may be separated according to their location into laterocervical cysts and fistulas or median cysts and fistulas. Their discovery may occur prematurely at birth or later during growth or in adulthood. Their treatment always requires surgical excision, which must be complete in order to prevent recurrences.

Genetic Advances in the Understanding of Microtia

Microtia is a genetic condition affecting the external ears and presents clinically along a wide spectrum: minimally affected ears are small with minor shape abnormalities; extremely affected ears lack all identifiable structures, with the most extreme being absence of the entire external ear. Multiple genetic causes have been linked to microtia in both animal models and humans, which are improving our understanding of the condition and may lead to the identification of a unified cause for the condition. Microtia is also a prominent feature of several genetic syndromes, the study of which has provided further insight into the possible causes and genetic mechanisms of the condition. This article reviews our current understanding of microtia including epidemiological characteristics, classification systems, environmental and genetic causative factors leading to microtia. Despite our increased understanding of the genetics of microtia, we do not have a means of preventing the condition and still rely on complex staged, surgical correction.

Genetic Screening in Patients with Craniofacial Malformations

Craniofacial malformations include a variety of anomalies, including cleft lip with or without cleft palate, craniosynostosis, microtia, and hemifacial microsomia. All of these anomalies can be either isolated or part of a defined genetic syndrome. A clinical geneticist or genetic counselor should be a member of the craniofacial team to help determine which patients have isolated anomalies and which are likely to have a syndrome. They would then arrange for the appropriate genetic testing to confirm the diagnosis of the specific syndrome. The identification of the specific syndrome is important for the overall care of the patient (as it identifies risk for other medical problems such as congenital heart defect) that will have to be taken into account in the care of the craniofacial malformation. In addition, knowing the specific syndrome will allow the family to understand how this happened to their child and the recurrence risk for future pregnancies. With the advent of new technologies, there are now many types of genetic testing available (including, karyotype, fluorescence in situ hybridization, chromosomal microarrays, and next generation sequencing) and the medical geneticist and genetic counselor can determine which specific testing is needed for a given patient.

Characterization of pediatric microtia cartilage: a reservoir of chondrocytes for auricular reconstruction using tissue engineering strategies

The external ear is composed of elastic cartilage. Microtia is a congenital malformation of the external ear that involves a small reduction in size or a complete absence. The aim of tissue engineering is to regenerate tissues and organs clinically implantable based on the utilization of cells and biomaterials. Remnants from microtia represent a source of cells for auricular reconstruction using tissue engineering. To examine the macromolecular architecture of microtia cartilage and behavior of chondrocytes, in order to enrich the knowledge of this type of cartilage as a cell reservoir. Auricular cartilage remnants were obtained from pediatric patients with microtia undergoing reconstructive procedures. Extracellular matrix composition was characterized using immunofluorescence and histological staining methods. Chondrocytes were isolated and expanded in vitro using a mechanical-enzymatic protocol. Chondrocyte phenotype was analyzed using qualitative PCR. Microtia cartilage preserves structural organization similar to healthy elastic cartilage. Extracellular matrix is composed of typical cartilage proteins such as type II collagen, elastin and proteoglycans. Chondrocytes displayed morphological features similar to chondrocytes derived from healthy cartilage, expressing SOX9, COL2 and ELN, thus preserving chondral phenotype. Cell viability was 94.6 % during in vitro expansion. Elastic cartilage from microtia has similar characteristics, both architectural and biochemical to healthy cartilage. We confirmed the suitability of microtia remnant as a reservoir of chondrocytes with potential to be expanded in vitro, maintaining phenotypical features and viability. Microtia remnants are an accessible source of autologous cells for auricular reconstruction using tissue engineering strategies.

Microarray analysis of microRNA expression in mouse fetus at 13.5 and 14.5 days post-coitum in ear and back skin tissues

There is no information regarding the role of microRNAs in the development of the external ear in mammals. The purpose of this study was to determine the stage-specific expression of microRNA during external ear development in mice under normal conditions. GeneChip miRNA 3.0 arrays by Affymetrix were used to obtain miRNA expression profiles from mice fetal pinnae and back skin tissues at 13.5 days-post-coitum (dpc) and 14.5 dpc. Biological triplicates for each tissue were analyzed; one litter represents one biological replica, each litter had 16 fetuses on average. The results were analyzed with Affymetrix's Transcriptome Analysis Console software to identify differentially expressed miRNAs. The inquiry showed significant differential expression of 25 miRNAs at 13.5 dpc and 31 at 14.5 dpc, some of these miRNAs were predicted to target genes implicated in external ear development. One example is mmu-miR-10a whose low expression in pinnae is known to impact ear development by modulating Hoxa1 mRNA levels Garzon et al. (2006), Gavalas et al. (1998) [1], [2]. Other findings like the upregulation of mmu-miR-200c and mmu-miR-205 in the pinnae tissues of healthy mice are in agreement with what has been reported in human patients with microtia, in which down regulation of both miRNAs has been found Li et al. (2013) [3].

This study uncovered a spatiotemporal pattern of miRNA expression in the external ear, which results from continuous transcriptional changes during normal development of body structures.

All microarray data are available at the Gene Expression Omnibus (GEO) at NCBI under accession number GSE64945.

A distal 594 bp ECR specifies Hmx1 expression in pinna and lateral facial morphogenesis and is regulated by the Hox-Pbx-Meis complex

Hmx1 encodes a homeodomain transcription factor expressed in the developing lateral craniofacial mesenchyme, retina and sensory ganglia. Mutation or mis-regulation of Hmx1 underlies malformations of the eye and external ear in multiple species. Deletion or insertional duplication of an evolutionarily conserved region (ECR) downstream of Hmx1 has recently been described in rat and cow, respectively. Here, we demonstrate that the impact of Hmx1 loss is greater than previously appreciated, with a variety of lateral cranioskeletal defects, auriculofacial nerve deficits, and duplication of the caudal region of the external ear. Using a transgenic approach, we demonstrate that a 594 bp sequence encompassing the ECR recapitulates specific aspects of the endogenous Hmx1 lateral facial expression pattern. Moreover, we show that Hoxa2, Meis and Pbx proteins act cooperatively on the ECR, via a core 32 bp sequence, to regulate Hmx1 expression. These studies highlight the conserved role for Hmx1 in BA2-derived tissues and provide an entry point for improved understanding of the causes of the frequent lateral facial birth defects in humans.

Microtia e atresia congênita do canal auditivo em cão: relato de caso

RESUMO Descreve-se o caso de um cão, Pinscher, fêmea de 11 meses de idade, com alteração anatômica da orelha do lado direito. Após avaliação, foi realizado o diagnóstico clínico e o radiográfico de microtia com atresia do canal auditivo do lado direito. Como o animal não apresentava sinais de alterações no sistema vestibular ou otite, optou-se pelo acompanhamento clínico do caso. A microtia, caracterizada pela hipoplasia parcial ou completa da pina, assim como outras anomalias do conduto auditivo, é raramente descrita em medicina veterinária. De acordo com a revisão de literatura realizada, este é o primeiro relato ocorrido no Brasil de um cão com microtia e atresia congênita do canal auditivo sem a associação de síndrome vestibular.

The Association of External and Middle Ear Anomaly and Mandibular Morphology in Congenital Microtia

OBJECTIVE

To investigate the relationship between the severity of ear anomaly and mandibular dysplasia in congenital microtia.

STUDY DESIGN

Retrospective case review.

SETTING

Sapporo Medical University Hospital.

PATIENTS

Congenital microtia: 44 patients over a period of 4 years.

INTERVENTIONS

The height of the condylar process of the mandible was assessed by three-dimensional computed tomography (CT), and the patients were divided into three groups based on the ratio of the condylar process height on the affected side to that on the unaffected side: Group A, ≥1.00; Group B, 0.99 to 0.85; Group C, <0.85. Developmental abnormalities of the ear were evaluated using Jahrsdoerfer's scoring system on high-resolution CT scans.

MAIN OUTCOME MEASURES

Nonparametric statistical tests were used to determine correlations between the height of the condylar process of the mandible and Jahrsdoerfer's score.

RESULTS

The total Jahrsdoerfer's score for each group was 7.36 ± 2.23, 7.28 ± 0.10, and 4.52 ± 0.30, respectively; this value was significantly lower in Group C than in the other groups. In terms of subtotal points, oval window open, middle ear aeration, and mastoid pneumatization correlated significantly with mandibular dysplasia. Patients in Group C tended to have grade III microtia, by Marx's classification. Facial nerve weakness was not significantly correlated with mandibular dysplasia.

CONCLUSIONS

In congenital microtia, mandibular development correlated significantly with aeration of the middle ear space, pneumatization of the mastoid, and formation of the oval window, but not with the presence of a bony part of the external auditory canal or with ossicular development.

Genome-wide association scan suggests basis for microtia in Awassi sheep

Hereditary underdevelopment of the ear, a condition also known as microtia, has been observed in several sheep breeds as well as in humans and other species. Its genetic basis in sheep is unknown. The Awassi sheep, a breed native to southwest Asia, carries this phenotype and was targeted for molecular characterization via a genome-wide association study. DNA samples were collected from sheep in Jordan. Eight affected and 12 normal individuals were genotyped with the Illumina OvineSNP50(®) chip. Multilocus analyses failed to identify any genotypic association. In contrast, a single-locus analysis revealed a statistically significant association (P = 0.012, genome-wide) with a SNP at basepair 34 647 499 on OAR23. This marker is adjacent to the gene encoding transcription factor GATA-6, which has been shown to play a role in many developmental processes, including chondrogenesis. The lack of extended homozygosity in this region suggests a fairly ancient mutation, and the time of occurrence was estimated to be approximately 3000 years ago. Many of the earless sheep breeds may thus share the causative mutation, especially within the subgroup of fat-tailed, wool sheep.

Long-Term Morphological and Microarchitectural Stability of Tissue-Engineered, Patient-Specific Auricles In Vivo

Current techniques for autologous auricular reconstruction produce substandard ear morphologies with high levels of donor-site morbidity, whereas alloplastic implants demonstrate poor biocompatibility. Tissue engineering, in combination with noninvasive digital photogrammetry and computer-assisted design/computer-aided manufacturing technology, offers an alternative method of auricular reconstruction. Using this method, patient-specific ears composed of collagen scaffolds and auricular chondrocytes have generated auricular cartilage with great fidelity following 3 months of subcutaneous implantation, however, this short time frame may not portend long-term tissue stability. We hypothesized that constructs developed using this technique would undergo continued auricular cartilage maturation without degradation during long-term (6 month) implantation. Full-sized, juvenile human ear constructs were injection molded from high-density collagen hydrogels encapsulating juvenile bovine auricular chondrocytes and implanted subcutaneously on the backs of nude rats for 6 months. Upon explantation, constructs retained overall patient morphology and displayed no evidence of tissue necrosis. Limited contraction occurred in vivo, however, no significant change in size was observed beyond 1 month. Constructs at 6 months showed distinct auricular cartilage microstructure, featuring a self-assembled perichondrial layer, a proteoglycan-rich bulk, and rounded cellular lacunae. Verhoeff's staining also revealed a developing elastin network comparable to native tissue. Biochemical measurements for DNA, glycosaminoglycan, and hydroxyproline content and mechanical properties of aggregate modulus and hydraulic permeability showed engineered tissue to be similar to native cartilage at 6 months. Patient-specific auricular constructs demonstrated long-term stability and increased cartilage tissue development during extended implantation, and offer a potential tissue-engineered solution for the future of auricular reconstructions.

Genome-wide association study identifies multiple susceptibility loci for craniofacial microsomia

Craniofacial microsomia (CFM) is a rare congenital anomaly that involves immature derivatives from the first and second pharyngeal arches. The genetic pathogenesis of CFM is still unclear. Here we interrogate 0.9 million genetic variants in 939 CFM cases and 2,012 controls from China. After genotyping of an additional 443 cases and 1,669 controls, we identify 8 significantly associated loci with the most significant SNP rs13089920 (logistic regression P=2.15 × 10(-120)) and 5 suggestive loci. The above 13 associated loci, harboured by candidates of ROBO1, GATA3, GBX2, FGF3, NRP2, EDNRB, SHROOM3, SEMA7A, PLCD3, KLF12 and EPAS1, are found to be enriched for genes involved in neural crest cell (NCC) development and vasculogenesis. We then perform whole-genome sequencing on 21 samples from the case cohort, and identify several novel loss-of-function mutations within the associated loci. Our results provide new insights into genetic background of craniofacial microsomia.

Roles of GASP-1 and GDF-11 in Dental and Craniofacial Development

PURPOSE

Growth and differentiation factor-11 (GDF-11) is a TGF-β family member that plays important regulatory roles in development of multiple tissues which include axial skeletal patterning, palatal closure, and tooth formation. Proteins that have been identified as GDF-11 inhibitors include GDF-associated serum protein-1 (GASP-1) and GASP-2. Recently, we found that mice genetically engineered to lack both Gasp1 and Gdf11 have an increased frequency of cleft palate. The goal of this study was to investigate the roles of GDF-11 and its inhibitors, GASP-1 and GASP-2, during dental and craniofacial development and growth.

METHODS

Mouse genetic studies were used in this study. Homozygous knockout mice for Gasp1 (Gasp1^-/- ) and Gasp2 (Gasp2^-/- ) were viable and fertile, but Gdf11 homozygous knockout (Gdf11^-/- ) mice died within 24 hours after birth. The effect of either Gasp1 or Gasp2 deletion in Gdf11^-/- mice during embryogenesis was evaluated in Gasp1^-/-;Gdf11^-/- and Gasp2^-/-;Gdf11^-/- mouse embryos at 18.5 days post-coitum (E18.5). For the analysis of adult tissues, we used Gasp1^-/-;Gdf11^+/- and Gasp2^-/-;Gdf11^+/- mice to evaluate the potential haploinsufficiency of Gdf11 in Gasp1^-/- and Gasp2^-/- mice.

RESULTS

Although Gasp2 expression decreased after E10.5, Gasp1 expression was readily detected in various ectodermal tissues at E17.5, including hair follicles, epithelium in nasal cavity, retina, and developing tooth buds. Interestingly, Gasp1^-/- ;Gdf11^-/- mice had abnormal formation of lower incisors: tooth buds for lower incisors were under-developed or missing. Although Gdf11^+/- mice were viable and had mild transformations of the axial skeleton, no specific defects in the craniofacial development have been observed in Gdf11^+/- mice. However, loss of Gasp1 in Gdf11^+/- mice occasionally resulted in small and abnormally shaped auricles.

CONCLUSIONS

These findings suggest that both GASP-1 and GDF-11 play important roles in dental and craniofacial development both during embryogenesis and in adult tissues.

The image variations in mastoid segment of facial nerve and sinus tympani in congenital aural atresia by HRCT and 3D VR CT

OBJECTIVE

To find the variations of middle ear structures including the spatial pattern of mastoid segment of facial nerve and the shapes of the sinus tympani in patients with congenital aural atresia (CAA) by using the high-resolution (HR) CT and 3D volume rendered (VR) CT images.

METHODS

HRCT was performed in 25 patients with congenital aural atresia including six bilateral atresia patients (n=25, 21 males, 4 females, mean age 13.8 years, range 6-19). Along the long axis of the posterior semicircular canal ampulla, the oblique axial multiplanar reconstruction (MPR) was set to view the depiction of the round window and the mastoid segment of facial nerve. Volumetric rending technique was used to demonstrate the morphologic features. HRCT and 3D VR findings in atresia ears were compared with those in 19 normal ears of the unilateral ears of atresia patients.

RESULTS

On the basic plane, the horizontal line distances between the mastoid segment of the facial nerve and the round window (h-RF) in atresia ears significantly decreased compared to the control ears (P<0.05). There was a significant negative correlation between the sinus tympani area (a-ST) and the distance between the horizontal lines of FN and RW midpoint (h-RF) (P<0.05). The mean area of sinus tympani in atresia group is larger (P<0.05). The shapes of the sinus tympani were classified into three categories: the cup-shaped, the pear-shaped and the boot-shaped. Area measurement indicated that the boot-shaped sinus tympani was a special variation with a large area, which only appears in CAA group. There were a significant difference between the area of the boot-shaped group and the other two groups (P<0.05). The morphologic differences of ST and other middle ear structures can also be observed visually in 3D VR CT images.

CONCLUSION

HRCT and 3D VR CT could help a better understanding of different kinds of variations in mastoid segment of facial nerve and sinus tympani in CAA ears. And it may further help surgeons to make the correct decision for hearing rehabilitation.

The prevalence of preauricular sinus and associated factors in a nationwide population-based survey of South Korea

OBJECTIVE

To investigate the prevalence of preauricular sinus (PAS) using data from a government-centered survey in South Korea and to reveal the relationship between the occurrence of PAS and associated factors.

PATIENTS

Data obtained during July 2008 to December 2012 were analyzed. Annually, 10,000 to 12,000 individuals are selected from a panel to represent the population using a multistage clustered and stratified random sampling method based on the National Census Data. A total of 56,592 individuals participated in the survey (25,586 male and 31,006 female).

INTERVENTION

After completion of the otolaryngologic questionnaires, the auricle was examined to check for malformation and PAS in those older than 1 year. Next, an otolaryngologist conducted a physical examination of the head and neck using videoassisted endoscopy.

MAIN OUTCOME MEASURE

Physical examination.

RESULTS

One thousand one hundred thirty-two individuals had PAS representing the overall prevalence of 1.91% in South Korea, with 79.08% of cases occurring unilaterally. Female participants had a significantly higher prevalence than male (p < 0.001), and a significant decrease with age was observed in both male and female populations (p < 0.001). A higher proportion of PAS was found in individuals with external ear anomaly (p < 0.001) and not associated with abnormal otoendoscopic findings such as tympanic membrane perforation, cholesteatomatous condition including retraction pocket, and middle ear effusion.

CONCLUSION

A large-scale government-centered survey demonstrates a high prevalence, female dominance, and age-related decrease of PAS in South Korea.

Biochemical properties of tissue-engineered cartilage

OBJECTIVE

Microtia is treated with rib cartilage sculpting and staged procedures; though aesthetically pleasing, these constructs lack native ear flexibility. Tissue-engineered (TE) elastic cartilage may bridge this gap; however, TE cartilage implants lead to hypertrophic changes with calcification and loss of flexibility. Retaining flexibility in TE cartilage must focus on increased elastin, maintained collagen II, decreased collagen X, with prevention of calcification. This study compares biochemical properties of human cartilage to TE cartilage from umbilical cord mesenchymal stem cells (UCMSCs). Our goal is to establish a baseline for clinically useful TE cartilage.

METHODS

Discarded cartilage from conchal bowl, microtic ears, preauricular tags, rib, and TE cartilage were evaluated for collagen I, II, X, calcium, glycosaminoglycans, elastin, and fibrillin I and III. Human UCMSCs were chondroinduced on 2D surfaces and 3D D,L-lactide-co-glycolic acid (PLGA) fibers.

RESULTS

Cartilage samples demonstrated similar staining for collagens I, II, and X, elastin, and fibrillin I and III, but differed from rib. TE pellets and PLGA-supported cartilage were similar to auricular samples in elastin and fibrillin I staining. TE samples were exclusively stained for fibrillin III. Only microtic samples demonstrated calcium staining.

CONCLUSIONS

TE cartilage expressed similar levels of elastin, fibrillin I, and collagens I and X when compared to native cartilage. Microtic cartilage demonstrated elevated calcium, suggesting this abnormal tissue may not be a viable cell source for TE cartilage. TE cartilage appears to recapitulate the embryonic development of fibrillin III, which is not expressed in adult tissue, possibly providing a strategy to control TE elastic cartilage phenotype.

Ectopic external auditory canal and ossicular formation in the oculo-auriculo-vertebral spectrum

Ear abnormalities in oculo-auricular-vertebral spectrum commonly present with varying degrees of external and middle ear atresias, usually in the expected locations of the temporal bone and associated soft tissues, without ectopia of the external auditory canal. We present the unique imaging of a 4-year-old girl with right hemifacial microsomia and ectopic location of an atretic external auditory canal, terminating in a hypoplastic temporomandibular joint containing bony structures with the appearance of auditory ossicles. This finding suggests an early embryological dysfunction involving Meckel's cartilage of the first branchial arch.

Auricular reconstruction of congenital microtia: personal experience in 225 cases

Microtia is a congenital disease with various degrees of severity, ranging from the presence of rudimentary and malformed vestigial structures to the total absence of the ear (anotia). The complex anatomy of the external ear and the necessity to provide good projection and symmetry make this reconstruction particularly difficult. The aim of this work is to report our surgical technique of microtic ear correction and to analyse the short and long term results. From 2000 to 2013, 210 patients affected by microtia were treated at the Maxillo-Facial Surgery Division, Head and Neck Department, University Hospital of Parma. The patient population consisted of 95 women and 115 men, aged from 7 to 49 years. A total of 225 reconstructions have been performed in two surgical stages basing of Firmin's technique with some modifications and refinements. The first stage consists in fabrication and grafting of a three-dimensional costal cartilage framework. The second stage is performed 5-6 months later: the reconstructed ear is raised up and an additional cartilaginous graft is used to increase its projection. A mastoid fascial flap together with a skin graft are then used to protect the cartilage graft. All reconstructions were performed without any major complication. The results have been considered satisfactory by all patients starting from the first surgical step. Low morbidity, the good results obtained and a high rate of patient satisfaction make our protocol an optimal choice for treatment of microtia. The surgeon's experience and postoperative patient care must be considered as essential aspects of treatment.

[Microtia-atresia: clinical, genetic and genomic aspects]

Mexico has a prevalence of microtia of 7.37/10,000 (newborns), 3 times higher than the prevalence reported in other populations (USA 2-3/10,000). Microtia is defined as a congenital malformation of the external ear characterized by a small auricular lobe with an abnormal shape. It is more often unilateral and on the right side. Males are more frequently affected than females. It can occur as an isolated defect or can be associated with other abnormalities such as stenosis of the external auditory canal. In three of the main pediatric hospitals in Mexico, microtia is among the most important causes of attendance in the Genetics Department. Microtia-atresia must be considered as a major malformation with important repercussions in hearing function requiring multidisciplinary medical care in order to limit the disability associated and to provide genetic counseling. Its etiology is complex. Only in a minor number of cases it has been possible to identify a main genetic component (as in monogenic presentations) or a main environmental cause (as in fetal alcohol syndrome or pregestational diabetes). In most cases this malformation is multifactorial. Due to the relevance that the frequency of microtia atresia has in different health services in Mexico, it is important that all medical professionals are aware of its clinical, molecular and inherited characteristics.

Understanding the molecular mechanisms of human microtia via a pig model of HOXA1 syndrome

Microtia is a congenital malformation of the outer ears. Although both genetic and environmental components have been implicated in microtia, the genetic causes of this innate disorder are poorly understood. Pigs have naturally occurring diseases comparable to those in humans, providing exceptional opportunity to dissect the molecular mechanism of human inherited diseases. Here we first demonstrated that a truncating mutation in HOXA1 causes a monogenic disorder of microtia in pigs. We further performed RNA sequencing (RNA-Seq) analysis on affected and healthy pig embryos (day 14.25). We identified a list of 337 differentially expressed genes (DEGs) between the normal and mutant samples, shedding light on the transcriptional network involving HOXA1. The DEGs are enriched in biological processes related to cardiovascular system and embryonic development, and neurological, renal and urological diseases. Aberrant expressions of many DEGs have been implicated in human innate deformities corresponding to microtia-associated syndromes. After applying three prioritizing algorithms, we highlighted appealing candidate genes for human microtia from the 337 DEGs. We searched for coding variants of functional significance within six candidate genes in 147 microtia-affected individuals. Of note, we identified one EVC2 non-synonymous mutation (p.Asp1174Asn) as a potential disease-implicating variant for a human microtia-associated syndrome. The findings advance our understanding of the molecular mechanisms underlying human microtia, and provide an interesting example of the characterization of human disease-predisposing variants using pig models.

Summary: A pig model of HOXA1 syndrome provides novel insight into the molecular mechanisms of human microtia.

Phenotypic sub-grouping in microtia using a statistical and a clinical approach

The clinical presentation of microtia varies widely from minimal morphological abnormalities to complete absence of the ear. In this study we sought to identify and characterize sub-groups of microtia using a statistical and a clinical approach. Photographs of 86 ears were classified in relation to all the external ear components. We used cluster analysis and rater's clinical opinion to identify groups with similar phenotypes in two separate analyses. We used Cramer's Phi coefficient of association to assess the similarity among the clinician's groupings as well as among the statistical sub-phenotypic groups and each of the clinician's groupings. The cluster analysis initially divided the 86 ears into a more and a less severe group. The less severe group included two sub-groups that included ears classified as normal and a group that had very few anomalous components. The group of 48 more affected ears all had abnormalities of the helix crus; antihelix-stem, -superior crus and -inferior crus; and antitragus. These were further divided into 4 sub-phenotypes. There was a moderate degree of association among the raters' groupings (Cramer's Phi: 0.64 to 0.73). The statistical and clinical groupings had a lower degree of association (Cramer's Phi: 0.49 to 0.58). Using standardized characterization of structural abnormalities of the ear we identified six distinct phenotypic groups; correlations with clinicians' groupings were moderate. These clusters may represent groups of ear malformations associated with the same etiology, similar time of insult or target cell population during embryonic development. The results will help inform investigations on etiology.

Johnson-McMillin Microtia Syndrome: New Additional Family

Microtia is a congenital anomaly that is found with different prevalence among various populations. The exact etiology of ear anomalies is still unknown. We describe a new additional family with this rare disorder; Johnson-McMillin syndrome (JMS) where mother, son, and distant grandmother have multiple features of JMS in the form of microtia, facial asymmetry, ear malformation, hearing defect, and hypotrichosis. Variable presentations in this family could be referred to phenotype variation supporting an autosomal dominant pattern of inheritance. We observed that the mother was very sad and suffered from feelings of guilt. We found that she had isolated herself from family and community out of fear of being stigmatized and hurt. We concluded that the occurrence of microtia is of public health importance, adhering to traditional marriage customs in Egypt increases women's risk of giving birth to a disabled child, yet the mothers are blamed and shamed for their children's birth defects by their husbands, families, and communities, while the fathers are not stigmatized.

Sociodemographic and hispanic acculturation factors and isolated anotia/microtia

BACKGROUND

It has been observed in several studies that infants with anotia/microtia are more common among Hispanics compared with other racial/ethnic groups. We examined the association between selected Hispanic ethnicity and acculturation factors and anotia/microtia in the National Birth Defects Prevention Study.

METHODS

We examined data from mothers of 351 infants with isolated anotia/microtia and 8435 unaffected infants from the National Birth Defects Prevention Study with an expected delivery date from 1997 to 2007. Sociodemographic, maternal, and acculturation factors (e.g., age, maternal education, household income, body mass index, gestational diabetes, folic acid, smoking, alcohol intake, study center, parental birthplace, and years lived in the United States, maternal language) were assessed as overall risk factors and also as risk factors among subgroups of Hispanics (United States- and foreign-born) versus non-Hispanic whites.

RESULTS

Compared with non-Hispanic whites, both United States- and foreign-born Hispanic mothers demonstrated substantially higher odds of delivering infants with anotia/microtia across nearly all strata of sociodemographic and other maternal factors (adjusted odds ratios range: 2.1-11.9). The odds of anotia/microtia was particularly elevated among Hispanic mothers who emigrated from Mexico after age five (adjusted odds ratios = 4.88; 95% confidence interval = 2.93-8.11) or who conducted the interview in Spanish (adjusted odds ratios = 4.97; 95% confidence interval = 3.00-8.24).

CONCLUSION

We observed that certain sociodemographic and acculturation factors are associated with higher risks of anotia/microtia among offspring of Hispanic mothers.

Genome-wide scan reveals LEMD3 and WIF1 on SSC5 as the candidates for porcine ear size

The quantitative trait loci (QTL) for porcine ear size was previously reported to mainly focus on SSC5 and SSC7. Recently, a missense mutation, G32E, in PPARD in the QTL interval on SSC7 was identified as the causative mutation for ear size. However, on account of the large interval of QTL, the responsible gene on SSC5 has not been identified. In this study, an intercross population was constructed from the large-eared Minzhu, an indigenous Chinese pig breed, and the Western commercial Large White pig to examine the genetic basis of ear size diversity. A GWAS was performed to detect SNPs significantly associated with ear size. Thirty-five significant SNPs defined a 10.78-Mb (30.14–40.92 Mb) region on SSC5. Further, combining linkage disequilibrium and haplotype sharing analysis, a reduced region of 3.07-Mb was obtained. Finally, by using a selective sweep analysis, a critical region of about 450-kb interval containing two annotated genes LEMD3 and WIF1 was refined in this work. Functional analysis indicated that both represent biological candidates for porcine ear size, with potential application in breeding programs. The two genes could also be used as novel references for further study of the mechanism underlying human microtia.

Genome-wide linkage study suggests a susceptibility locus for isolated bilateral microtia on 4p15.32-4p16.2

Microtia is a congenital deformity where the external ear is underdeveloped. Genetic investigations have identified many susceptibility genes of microtia-related syndromes. However, no causal genes were reported for isolated microtia, the main form of microtia. We conducted a genome-wide linkage analysis on a 5-generation Chinese pedigree with isolated bilateral microtia. We identified a suggestive linkage locus on 4p15.32-4p16.2 with parametric LOD score of 2.70 and nonparametric linkage score (Zmean) of 12.28 (simulated occurrence per genome scan equal to 0.46 and 0.47, respectively). Haplotype reconstruction analysis of the 4p15.32-4p16.2 region further confined the linkage signal to a 10-Mb segment located between rs12505562 and rs12649803 (9.65-30.24 cM; 5.54-15.58 Mb). Various human organ developmental genes reside in this 10-Mb susceptibility region, such as EVC, EVC2, SLC2A9, NKX3-2, and HMX1. The coding regions of three genes, EVC known for cartilage development and NKX3-2, HMX1 involved in microtia, were selected for sequencing with 5 individuals from the pedigree. Of the 38 identified sequence variants, none segregates along with the disease phenotype. Other genes or DNA sequences of the 10-Mb region warrant for further investigation. In conclusion, we report a susceptibility locus of isolated microtia, and this finding will encourage future studies on the genetic basis of ear deformity.

Microtia in the Netherlands: clinical characteristics and associated anomalies

BACKGROUND

In Europe there have been few detailed reports on the clinical characteristics of microtia patient populations. The objective of the present study is to contribute to our insight of microtia in Europe by examining the Dutch microtia population treated in the University Medical Center Utrecht (UMCU) with regards to its clinical features and associated anomalies. In addition, an overview of the literature is provided for thorough comparison.

METHODS

A retrospective chart review was performed for all microtia patients referred to the UMCU for reconstructive surgery of the auricle over the period 1990-2012. Previous studies were identified by a systematic search of the electronic literature databases PubMed and Embase. In a subsequent meta-analysis the results from the literature review were pooled by geographical region to facilitate comparison.

RESULTS

A total of 204 microtia patients were referred for reconstructive surgery during 1990-2012. This group was characterized by a male predominance of 60.8%. Unilateral disease was observed in 91.7% of patients, affecting the right auricle in 66.3%. In unilateral patients lobule type microtia was seen in 59.9%, (small) concha type in 34.4% and anotia in 5.7%. The more frequent anomalies associated with microtia were atresia of the acoustic meatus (76.0%), preauricular skin tags (30.5%), hemifacial microsomia (27.5%), facial nerve paralysis (8.3%) and congenital heart disease (2.5%). Familial occurrence of microtia was reported for 2.0% of UMCU patients and for 10.0% of patients in the literature.

CONCLUSION

The clinical characteristics of microtia in the Netherlands correspond to those reported for other patient populations in the literature. Most congenital anomalies associated with microtia in Dutch patients belong to the Oculo-Auriculo-Vertebral Spectrum. The considerable degree of familial microtia observed in the literature points to a substantial genetic component in the etiology of the condition.

The genetics of auricular development and malformation: new findings in model systems driving future directions for microtia research

Microtia is a term used to describe a wide array of phenotypic presentations of the outer ear. Although the majority of the cases are isolated in nature, much of our understanding of the causes of microtia has been driven by the identification of genes underlying syndromic forms where the anomaly co-presents with various other craniofacial and extra-craniofacial structural defects. In this review we discuss recent findings in mice deficient in Hoxa2, a key regulator of branchial arch patterning, which has necessitated a revision to the canonical model of pinna morphogenesis. The revised model will likely impact current classification schemes for microtia and, as we argue in this review, the interpretation of the developmental basis for various auricular malformations. In addition, we highlight recent studies in other mammalian species that are providing the first clues as to possible causes of at least some isolated anomalies and thus should now accelerate the search for the more elusive genetic contributions to the many isolated and non-syndromic cases of microtia. These findings, together with the application of new genome-level sequencing technologies and more thorough quantitative assessment of available mutant mouse resources, promise an exciting future for genetic studies in microtia.

Auricular reconstruction for microtia: A review of available methods

Several surgical techniques have been described for auricular reconstruction. Autologous reconstruction using costal cartilage is the most widely accepted technique of microtia repair. However, other techniques have certain indications and should be discussed with patients and families when planning for an auricular reconstruction. In the present review, the authors discuss the main surgical techniques for auricular reconstruction including autologous costal cartilage graft, Medpor (Stryker, USA) implant and prosthetic reconstruction. To further elaborate on the advantages and disadvantages of each technique, the authors invited leaders in this field, Dr Nagata, Dr Park, Dr Reinisch and Dr Wilkes, to comment on their own technique and provide examples of their methods.

Clinical care in craniofacial microsomia: a review of current management recommendations and opportunities to advance research

Craniofacial microsomia (CFM) is a complex condition associated with microtia, mandibular hypoplasia, and preauricular tags. It is the second most common congenital facial condition treated in many craniofacial centers and requires longitudinal multidisciplinary patient care. The purpose of this article is to summarize current recommendations for clinical management and discuss opportunities to advance clinical research in CFM.