Damaging variants in FOXI3 cause microtia and craniofacial microsomia.

PURPOSE: Craniofacial microsomia (CFM) represents a spectrum of craniofacial malformations, ranging from isolated microtia with or without aural atresia to underdevelopment of the mandible, maxilla, orbit, facial soft tissue, and/or facial nerve. The genetic causes of CFM remain largely unknown. METHODS: We performed genome sequencing and linkage analysis in patients and families with microtia and CFM of unknown genetic etiology. The functional consequences of damaging missense variants were evaluated through expression of wild-type and mutant proteins in vitro. RESULTS: We studied a 5-generation kindred with microtia, identifying a missense variant in FOXI3 (p.Arg236Trp) as the cause of disease (logarithm of the odds = 3.33). We subsequently identified 6 individuals from 3 additional kindreds with microtia-CFM spectrum phenotypes harboring damaging variants in FOXI3, a regulator of ectodermal and neural crest development. Missense variants in the nuclear localization sequence were identified in cases with isolated microtia with aural atresia and found to affect subcellular localization of FOXI3. Loss of function variants were found in patients with microtia and mandibular hypoplasia (CFM), suggesting dosage sensitivity of FOXI3. CONCLUSION: Damaging variants in FOXI3 are the second most frequent genetic cause of CFM, causing 1% of all cases, including 13% of familial cases in our cohort.

Parental Reports of Intervention Services and Prevalence of Teasing in a Multinational Craniofacial Microsomia Pediatric Study.

ABSTRACT: Children with craniofacial microsomia (CFM) are at increased risk for educational and social concerns. This study describes intervention services and frequency of teasing in a multinational population of children with CFM. Caregivers of children with CFM ages 3 to 18 years in the US and South America were administered a questionnaire. Additional information was gathered from medical charts and photographs. Participants (N = 169) had an average age of 10.1 ±â€Š6.2 years, were primarily male (60%), and from the US (46%) or Colombia (32%). Most participants had microtia and mandibular hypoplasia (70%). They often had unilateral (71%) or bilateral (19%) hearing loss and 53% used a hearing aid. In the US, special education services were provided for 48% of participants enrolled in school; however, similar services were rare (4%) in South America and reflect differences in education systems. Access to any intervention service was higher in the US (80%) than in South America (48%). Caregivers reported children showed diagnosis awareness by an average age of 4.4 ±â€Š1.9 years. Current or past teasing was reported in 41% of the children, starting at a mean age of 6.0 ±â€Š2.4 years, and most often took place at school (86%). As half of the US participants received developmental and academic interventions, providers should screen for needs and facilitate access to services. Given diagnosis awareness at age 4 and teasing at age 6, providers are encouraged to assess for psychosocial concerns and link to resources early in treatment.

Haploinsufficiency of SF3B2 causes craniofacial microsomia.

Craniofacial microsomia (CFM) is the second most common congenital facial anomaly, yet its genetic etiology remains unknown. We perform whole-exome or genome sequencing of 146 kindreds with sporadic (n = 138) or familial (n = 8) CFM, identifying a highly significant burden of loss of function variants in SF3B2 (P = 3.8 × 10-10), a component of the U2 small nuclear ribonucleoprotein complex, in probands. We describe twenty individuals from seven kindreds harboring de novo or transmitted haploinsufficient variants in SF3B2. Probands display mandibular hypoplasia, microtia, facial and preauricular tags, epibulbar dermoids, lateral oral clefts in addition to skeletal and cardiac abnormalities. Targeted morpholino knockdown of SF3B2 in Xenopus results in disruption of cranial neural crest precursor formation and subsequent craniofacial cartilage defects, supporting a link between spliceosome mutations and impaired neural crest development in congenital craniofacial disease. The results establish haploinsufficient variants in SF3B2 as the most prevalent genetic cause of CFM, explaining ~3% of sporadic and ~25% of familial cases.

Cognitive, Motor, and Language Development of Preschool Children With Craniofacial Microsomia.

OBJECTIVE: To examine neurodevelopment in preschool-aged children with craniofacial microsomia (CFM) relative to unaffected peers. DESIGN: Multisite, longitudinal cohort study. SETTING: Tertiary care centers in the United States. PARTICIPANTS: We included 92 children with CFM ("cases") through craniofacial centers and clinics. Seventy-six children without CFM (controls) were included from pediatric practices and community advertisements. This study reports on outcomes assessed when participants were an average age of 38.4 months (SD = 1.9). MAIN OUTCOME MEASURES: We assessed cognitive and motor skills using the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III), and language function using subtests from the Clinical Evaluation of Language Fundamentals-Preschool, second edition (CELF-P2). RESULTS: Case-control differences were negligible for Bayley-III cognitive (effect sizes [ES] = -0.06, P = .72) and motor outcomes (ES = -0.19, P = .25). Cases scored lower than controls on most scales of the CELF-P2 (ES = -0.58 to -0.20, P = .01 to .26). Frequency counts for "developmental delay" (ie, one or more scores > 1 SD below the normative mean) were higher for cases (39%) than controls (15%); however, the adjusted odds ratio = 1.73 (P = 0.21) was not significant. Case-control differences were most evident in children with microtia or other combinations of CFM-related facial features. CONCLUSIONS: Cognitive and motor scores were similar for preschool-aged children with and without CFM. However, children with CFM scored lower than controls on language measures. We recommend early monitoring of language to identify preschoolers with CFM who could benefit from intervention.

Behavioral Adjustment of Preschool Children With and Without Craniofacial Microsomia.

OBJECTIVE: The study aim was to assess behavioral adjustment in preschool children with and without craniofacial microsomia (CFM). DESIGN: Multisite cohort study of preschoolers with CFM ("cases") or without CFM ("controls"). PARTICIPANTS: Mothers (89%), fathers (9%), and other caregivers (2%) of 161 preschoolers. OUTCOME MEASURE: Child Behavior Check List (CBCL 1.5-5); linear regressions with standardized effect sizes (ES) adjusted for sociodemographic confounds. RESULTS: Child Behavior Check Lists for 89 cases and 72 controls (average age 38.3 ± 1.9 months). Children were male (54%), white (69%), and of Latino ethnicity (47%). Cases had microtia with mandibular hypoplasia (52%), microtia only (30%), or other CFM-associated features (18%). Nearly 20% of cases had extracranial anomalies. Composite CBCL scores were in the average range compared to test norms and similar for cases and controls. On the subscales, cases' parents reported higher Anxious/Depressed scores (ES = 0.35, P = .04), Stress Problems (ES = 0.40, P = .04), Anxiety Problems (ES = 0.34, P = .04), and Autism Spectrum Problems (ES = 0.41, P = .02); however, the autism subscale primarily reflected speech concerns. Among cases, more problems were reported for children with extracranial anomalies and certain phenotypic categories with small ES. CONCLUSIONS: Behavioral adjustment of preschoolers with CFM was comparable to peers. However, parental reports reflected greater concern for internalizing behaviors; thus, anxiety screening and interventions may benefit children with CFM. Among cases, more problems were reported for those with more complex presentations of CFM. Craniofacial microsomia-related speech problems should be distinguished from associated psychosocial symptoms during developmental evaluations.

MYT1 role in the microtia-craniofacial microsomia spectrum.

BACKGROUND: Craniofacial microsomia (CFM), also known as the oculo-auriculo-vertebral spectrum, comprises a variable phenotype with the most common features including microtia and mandibular hypoplasia on one or both sides, in addition to lateral oral clefts, epibulbar dermoids, cardiac, vertebral, and renal abnormalities. The etiology of CFM is largely unknown. The MYT1 gene has been reported as a candidate based in mutations found in three unrelated individuals. Additional patients with mutations in this gene are required to establish its causality. We present two individuals with CFM that have rare variants in MYT1 contributing to better understand the genotype and phenotype associated with mutations in this gene. METHODS/RESULTS: We conducted genetic analysis using whole-exome and -genome sequencing in 128 trios with CFM. Two novel MYT1 mutations were identified in two participants. Sanger sequencing was used to confirm these mutations. CONCLUSION: We identified two additional individuals with CFM who carry rare variants in MYT1, further supporting the presumptive role of this gene in the CFM spectrum.

Microtia and craniofacial microsomia: Content analysis of facebook groups.

OBJECTIVE: An increasing number of patients use social media for health-related information and social support. This study's objective was to describe the content posted on Facebook groups for individuals with microtia and/or craniofacial microsomia (CFM) and their families in order for providers to gain insight into patient and family needs and experiences to inform clinical care. METHODS: Two months of posts, images, comments, and "like" responses from two Facebook groups in the US and the UK were recorded and analyzed using content analysis. A secondary analysis identified statements of emotion. RESULTS: Posts (N = 254) had a total of 7912 "like" responses, 2245 comments, and 153 images. There were three categories of posts: seeking guidance (43%; 9 themes), promoting events/news (33%; 5 themes), and sharing experiences (24%; 3 themes). Across categories, 16% of posts had emotional content. Most comments were responding to posts seeking guidance, including medical care (20%), surgical care (9%), and hearing aids (5%). Promotional posts often aimed to increase CFM awareness. Posts sharing experiences were generally positive, with the highest number of "likes". CONCLUSIONS: Facebook groups members frequently exchanged health-related information, suggesting value placed on input from other families and the convenience of seeking information online. Posts also promoted awareness and shared experiences. Clinical care implications include the need for easily accessible accurate and tailored CFM-related health education. Additionally, providers should demonstrate awareness of health information on social media and may address the potential emotional impact of CFM by facilitating access to resources for social support.

Evaluation of prenatal diabetes mellitus and other risk factors for craniofacial microsomia.

OBJECTIVES: Craniofacial microsomia (CFM) is a congenital condition that typically involves hypoplasia of the ear and jaw. It is often associated with adverse effects such as hearing loss and sleep-disordered breathing. There is little research on its etiology. METHODS: We conducted a case-control study from maternal interview data collected from mothers of infants with and without CFM. The study included 108 children with and 84 children without CFM. Logistic regression with adjustment for demographic factors was used to evaluate associations between maternal exposures of interest and risk for CFM overall, as well as for different phenotypic sub-groups of children on the CFM spectrum. RESULTS: We found a statistically significant association between diabetes mellitus (DM) and CFM (OR 4.01, 95% CI 1.6-10.5). The association was slightly attenuated after adjustment for BMI. Higher parity was also associated with increased risk for CFM (OR 2.0, 95% CI 1.0-4.0). Vitamin A consumption and/or liver consumption was associated with a 70% lower risk compared with non-users (OR 0.3, 95% 0.1-0.8). Maternal age at the time of pregnancy was not associated with CFM. CONCLUSIONS: These analyses contribute evidence linking maternal DM with an elevated risk of having an infant with CFM, which is consistent with previous research and adds to the body of knowledge about the strength of this association. Further study is warranted to understand the potential mechanisms underlying the effect of DM in the developing embryo.

Methods and Challenges in a Cohort Study of Infants and Toddlers With Craniofacial Microsomia: The Clock Study.

OBJECTIVE: The Craniofacial microsomia: Longitudinal Outcomes in Children pre-Kindergarten (CLOCK) study is a longitudinal cohort study of neurobehavioral outcomes in infants and toddlers with craniofacial microsomia (CFM). In this article, we review the data collection and methods used to characterize this complex condition and describe the demographic and clinical characteristics of the cohort. SETTING: Craniofacial and otolaryngology clinics at 5 study sites. PARTICIPANTS: Infants with CFM and unaffected infants (controls) ages 12 to 24 months were recruited from the same geographical regions and followed to age 36 to 48 months. METHODS: Phenotypic, neurodevelopmental, and facial expression assessments were completed during the first and third waves of data collection (time 1 and time 3, respectively). Medical history data were taken at both of these time points and during an intermediate parent phone interview (time 2). RESULTS: Our cohort includes 108 cases and 84 controls. Most cases and controls identified as white and 55% of cases and 37% of controls identified as Hispanic. Nearly all cases had microtia (95%) and 59% had mandibular hypoplasia. Cases received extensive clinical care in infancy, with 59% receiving care in a craniofacial clinic and 28% experiencing at least one surgery. Study visits were completed at a study site (92%) or at the participant's home (8%). CONCLUSIONS: The CLOCK study represents an effort to overcome the challenges of characterizing the phenotypic and neurodevelopmental outcomes of CFM in a large, demographically and geographically diverse cohort.

In Their Own Words: Caregiver and Patient Perspectives on Stressors, Resources, and Recommendations in Craniofacial Microsomia Care.

This study describes stressors, resources, and recommendations related to craniofacial microsomia (CFM) care from the perspective of caregivers of children with CFM and adults with CFM to inform improved quality of healthcare delivery. A mixed method design was used with fixed-response and open-ended questions from an online survey in English. The survey included demographics, CFM phenotypic information, and items about CFM-related experiences across settings. Themes were identified by qualitative analysis of responses to open-ended questions. Respondents (n = 51) included caregivers (n = 42; 90% mothers) and adults with CFM (n = 9; 78% female), who had a mean age of 45 ±â€Š6 years. Most children were male (71%) with an average age of 7 ±â€Š4 years. Respondents were primarily white (80%), non-Hispanic (89%), from the United States (82%), had a college degree (80%), and had private health insurance (80%). Reflecting the high rate of microtia (84%) in the sample, themes centered on the impact of hearing difficulties across settings with related language concerns. Negative social experiences were frequently described and school needs outlined. Multiple medical stressors were identified and corresponding suggestions included: providers need to be better informed about CFM, treatment coordination among specialists, and preference for a family-centered approach with reassurance, empathy, and clear communication. Advice offered to others with CFM included positive coping strategies. Overall, caregivers' and patients' responses reflected the complexity of CFM treatment. Incorporating these perspectives into routine CFM care has the potential to reduce family distress while improving their healthcare.

Neurodevelopment of Infants with and without Craniofacial Microsomia.

OBJECTIVES: To determine whether infant cases with craniofacial microsomia (CFM) evidence poorer neurodevelopmental status than demographically similar infants without craniofacial diagnoses ("controls"), and to examine cases' neurodevelopmental outcomes by facial phenotype and hearing status. STUDY DESIGN: Multicenter, observational study of 108 cases and 84 controls aged 12-24 months. Participants were assessed by the Bayley Scales of Infant and Toddler Development-Third Edition and the Preschool Language Scales-Fifth Edition (PLS-5). Facial features were classified with the Phenotypic Assessment Tool for Craniofacial Microsomia. RESULTS: After adjustment for demographic variables, there was little difference in Bayley Scales of Infant and Toddler Development-Third Edition or Preschool Language Scales-Fifth Edition outcomes between cases and controls. Estimates of mean differences ranged from -0.23 to 1.79 corresponding to standardized effect sizes of -.02 to 0.12 (P values from .30 to .88). Outcomes were better among females and those with higher socioeconomic status. Among cases, facial phenotype and hearing status showed little to no association with outcomes. Analysis of individual test scores indicated that 21% of cases and 16% of controls were developmentally delayed (OR 0.68, 95% CI 0.29-1.61). CONCLUSIONS: Although learning problems have been observed in older children with CFM, we found no evidence of developmental or language delay among infants. Variation in outcomes across prior studies may reflect differences in ascertainment methods and CFM diagnostic criteria.

Healthcare and psychosocial experiences of individuals with craniofacial microsomia: Patient and caregivers perspectives.

OBJECTIVE: Craniofacial microsomia (CFM) is primarily characterized by underdevelopment of the ear and mandible, with several additional possible congenital anomalies. Despite the potential burden of care and impact of CFM on multiple domains of functioning, few studies have investigated patient and caregiver perspectives. The objective of this study was to explore the diagnostic, treatment-related, and early psychosocial experiences of families with CFM with the aim of optimizing future healthcare delivery. METHODS: Forty-two caregivers and nine adults with CFM responded to an online mixed-methods survey. Descriptive statistics and qualitative methods were used for the analysis. RESULTS: Survey respondents reported high rates of subspecialty evaluations, surgeries, and participation in therapies. Some participants reported receiving inaccurate or incomplete information about CFM and experienced confusion about etiology. Communication about CFM among family members included mostly positive messages. Self-awareness of facial differences began at a mean age of three years and teasing at mean age six, with 43% of individuals four years or older reporting teasing. Teasing often involved name-calling and frequent reactions were ignoring and negative emotional responses. Participants ranked "understanding diagnosis and treatment" as a top priority for future research and had the most questions about etiology and treatment guidance. CONCLUSIONS: The survey results on the healthcare and psychosocial experiences from birth through adulthood of individuals with CFM reinforce the need for ongoing psychological assessment and intervention. Healthcare provision could be improved through establishing diagnostic criteria and standardized treatment guidelines, as well as continued investigation of CFM etiology.

Intelligence and Academic Achievement of Adolescents with Craniofacial Microsomia.

BACKGROUND: The authors compared the IQ and academic achievement of adolescents with craniofacial microsomia (cases) and unaffected children (controls). Among cases, the authors analyzed cognitive functioning by facial phenotype. METHODS: The authors administered standardized tests of intelligence, reading, spelling, writing, and mathematics to 142 cases and 316 controls recruited from 26 cities across the United States and Canada. Phenotypic classification was based on integrated data from photographic images, health history, and medical chart reviews. Hearing screens were conducted for all participants. RESULTS: After adjustment for demographics, cases' average scores were lower than those of controls on all measures, but the magnitude of differences was small (standardized effect sizes, -0.01 to -0.3). There was little evidence that hearing status modified case-control group differences (Wald p > 0.05 for all measures). Twenty-five percent of controls and 38 percent of cases were classified as having learning problems (adjusted OR, 1.5; 95 percent CI, 0.9 to 2.4). Comparison of cases with and without learning problems indicated that those with learning problems were more likely to be male, Hispanic, and to come from lower income, bilingual families. Analyses by facial phenotype showed that case-control group differences were largest for cases with both microtia and mandibular hypoplasia (effect sizes, -0.02 to -0.6). CONCLUSIONS: The highest risk of cognitive-academic problems was observed in patients with combined microtia and mandibular hypoplasia. Developmental surveillance of this subgroup is recommended, especially in the context of high socioeconomic risk and bilingual families. Given the early stage of research on craniofacial microsomia and neurodevelopment, replication of these findings is needed. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

Phenotypic characterization of epibulbar dermoids.

The purpose of this study was to characterize the phenotypic presentation, clinical course, and outcomes of epibulbar dermoids (EpDs) which are the most common congenital eye tumor in children. Sixty-eight dermoids were identified in 58 eyes of 48 patients of Seattle Children's Hospital between 1981 and 2014 via electronic medical record search. Patients were organized into: "EpD-Only" [patients without other congenital anomalies (n = 13)], "EpD-CFM" [patients with a craniofacial microsomia (CFM) diagnosis (n = 25)], and "EpD-Other" [patients with other congenital anomalies (n = 10)]. All EpD in the EpD-Only group were unilateral and singular, while the EpD-CFM group had six cases with multiple unilateral EpD and five cases with bilateral EpD. In the EpD-Only group, 69 % of EpD were left sided, whereas in the EpD-CFM group, there was no side predisposition. Among both groups, the majority of EpD were limbal or lipodermoids in the inferotemporal quadrant of the eye. Surgery was more common and at a younger age in the EpD-CFM group than the EpD-Only group (56 vs. 38 %, 5.2 vs. 7.0 years). Follow-up surgeries occurred only in the EpD-CFM group (21 %). EpDs were most commonly associated with preauricular tags, congenital heart defects, genitourinary, and nervous system anomalies. Whereas the location and type of EpDs did not significantly differ between the groups, the phenotype in the EpD-Only group appears to be less complex. This may indicate an important difference between EpDs in isolation and those within CFM. Additional studies will further characterize these phenotypes and outcomes.

Hearing Loss in Children With Craniofacial Microsomia.

OBJECTIVE: To evaluate the association between craniofacial phenotype and hearing loss in children with craniofacial microsomia. DESIGN: Retrospective cohort study. SETTING: Tertiary care children's hospital. PATIENTS: Individuals with craniofacial microsomia. MAIN OUTCOME MEASURES: Ear-specific audiograms and standardized phenotypic classification of facial characteristics. RESULTS: A total of 79 participants were included in the study. The mean age was 9 years (range, 1 to 23 years) and approximately 60% were boys. Facial anomalies were bilateral in 39 participants and unilateral in 40 participants (24 right, 16 left). Microtia (hypoplasia of the ear) was the most common feature (94%), followed by mandibular hypoplasia (76%), soft tissue deficiency (60%), orbital hypoplasia or displacement (53%), and facial nerve palsy (32%). Sixty-five individuals had hearing loss (12 bilateral and 53 unilateral). Hearing loss was conductive in 73% of affected ears, mixed in 10%, sensorineural in 1%, and indeterminate in 16%. Hypoplasia of the ear or mandible was frequently associated with ipsilateral hearing loss, although contralateral hearing loss occurred in 8% of hemifaces. CONCLUSIONS: Hearing loss is strongly associated with malformations of the ipsilateral ear in craniofacial microsomia and is most commonly conductive. Hearing loss can occur contralaterally to the side with malformations in children with apparent hemifacial involvement. Children with craniofacial microsomia should receive early diagnostic hearing assessments.

Characterizing facial features in individuals with craniofacial microsomia: A systematic approach for clinical research.

BACKGROUND: Craniofacial microsomia (CFM) is a congenital condition with wide phenotypic variability, including hypoplasia of the mandible and external ear. We assembled a cohort of children with facial features within the CFM spectrum and children without known craniofacial anomalies. We sought to develop a standardized approach to assess and describe the facial characteristics of the study cohort, using multiple sources of information gathered over the course of this longitudinal study and to create case subgroups with shared phenotypic features. METHODS: Participants were enrolled between 1996 and 2002. We classified the facial phenotype from photographs, ratings using a modified version of the Orbital, Ear, Mandible, Nerve, Soft tissue (OMENS) pictorial system, data from medical record abstraction, and health history questionnaires. RESULTS: The participant sample included 142 cases and 290 controls. The average age was 13.5 years (standard deviation, 1.3 years; range, 11.1-17.1 years). Sixty-one percent of cases were male, 74% were white non-Hispanic. Among cases, the most common features were microtia (66%) and mandibular hypoplasia (50%). Case subgroups with meaningful group definitions included: (1) microtia without other CFM-related features (n = 24), (2) microtia with mandibular hypoplasia (n = 46), (3) other combinations of CFM- related facial features (n = 51), and (4) atypical features (n = 21). CONCLUSION: We developed a standardized approach for integrating multiple data sources to phenotype individuals with CFM, and created subgroups based on clinically-meaningful, shared characteristics. We hope that this system can be used to explore associations between phenotype and clinical outcomes of children with CFM and to identify the etiology of CFM. Birth Defects Research (Part A) 106:915-926, 2016.© 2016 Wiley Periodicals, Inc.

Reliable classification of facial phenotypic variation in craniofacial microsomia: a comparison of physical exam and photographs.

BACKGROUND: Craniofacial microsomia is a common congenital condition for which children receive longitudinal, multidisciplinary team care. However, little is known about the etiology of craniofacial microsomia and few outcome studies have been published. In order to facilitate large, multicenter studies in craniofacial microsomia, we assessed the reliability of phenotypic classification based on photographs by comparison with direct physical examination. METHODS: Thirty-nine children with craniofacial microsomia underwent a physical examination and photographs according to a standardized protocol. Three clinicians completed ratings during the physical examination and, at least a month later, using respective photographs for each participant. We used descriptive statistics for participant characteristics and intraclass correlation coefficients (ICCs) to assess reliability. RESULTS: The agreement between ratings on photographs and physical exam was greater than 80 % for all 15 categories included in the analysis. The ICC estimates were higher than 0.6 for most features. Features with the highest ICC included: presence of epibulbar dermoids, ear abnormalities, and colobomas (ICC 0.85, 0.81, and 0.80, respectively). Orbital size, presence of pits, tongue abnormalities, and strabismus had the lowest ICC, values (0.17 or less). There was not a strong tendency for either type of rating, physical exam or photograph, to be more likely to designate a feature as abnormal. The agreement between photographs and physical exam regarding the presence of a prior surgery was greater than 90 % for most features. CONCLUSIONS: Our results suggest that categorization of facial phenotype in children with CFM based on photographs is reliable relative to physical examination for most facial features.

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.

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.