OTX2 duplication is implicated in hemifacial microsomia

Pediatric Temporomandibular Joint Pathology

Pediatric temporomandibular joint (TMJ) disorders represent a broad range of congenital and acquired diagnoses. Dentofacial deformities, including facial asymmetry, retrognathism, and malocclusion, commonly develop. Compared with adult TMJ conditions, pain and articular disc pathology are less common. Accurate diagnosis is paramount in planning and prognostication. Several specific considerations apply in preparation for skeletal correction, including timing in relation to disease progression and growth trajectory, expectation for postcorrection stability, reconstructive technique as it applies to expected durability and need for future revision, management of occlusion, and need for ancillary procedures to optimize correction. This article reviews common conditions and treatment considerations.

Whole genome sequencing of a family with autosomal dominant features within the oculoauriculovertebral spectrum

Background

Oculoauriculovertebral Spectrum (OAVS) encompasses abnormalities on derivatives from the first and second pharyngeal arches including macrostomia, hemifacial microsomia, micrognathia, preauricular tags, ocular and vertebral anomalies. We present genetic findings on a three-generation family affected with macrostomia, preauricular tags and uni- or bilateral ptosis following an autosomal dominant pattern.

Methods

We generated whole genome sequencing data for the proband, affected parent and unaffected paternal grandparent followed by Sanger sequencing on 23 family members for the top 10 candidate genes: KCND2, PDGFRA, CASP9, NCOA3, WNT10A, SIX1, MTF1, KDR/VEGFR2, LRRK1, and TRIM2 We performed parent and sibling-based transmission disequilibrium tests and burden analysis via a penalized linear mixed model, for segregation and mutation burden respectively. Next, via bioinformatic tools we predicted protein function, mutation pathogenicity and pathway enrichment to investigate the biological relevance of mutations identified.

Results

Rare missense mutations in SIX1, KDR/VEGFR2, and PDGFRA showed the best segregation with the OAV phenotypes in this family. When considering any of the 3 OAVS phenotypes as an outcome, SIX1 had the strongest associations in parent-TDTs and sib-TDTs (p=0.025, p=0.052) (unadjusted p-values). Burden analysis identified SIX1 (RC=0.87) and PDGFRA (RC=0.98) strongly associated with OAVS severity. Using phenotype-specific outcomes, sib-TDTs identified SIX1 with uni- or bilateral ptosis (p=0.049) and ear tags (p=0.01), and PDGFRA and KDR/VEGFR2 with ear tags (both p<0.01).

Conclusion

SIX1, PDGFRA, and KDR/VEGFR2 are strongly associated to OAVS phenotypes. SIX1 has been previously associated with OAVS ear malformations and is co-expressed with EYA1 during ear development. Efforts to strengthen the genotype-phenotype co-relation underlying the OAVS are key to discover etiology, family counseling and prevention.

14q22.3 duplication including OTX2 in a girl with medulloblastoma: A case report with literature review

Orthodenticle homeobox 2 (OTX2) is a known oncogenic driver of medulloblastoma. Germline duplication of 14q22.3 including OTX2 is a rare condition reported in patients with combined pituitary hormone deficiency, oculo-auriculo-vertebral spectrum, and hemifacial microsomia. There has been one previously published case of a patient carrying a 14q22.3 duplication that included OTX2 with hemifacial microsomia who also developed medulloblastoma. Here, we present a case of a 6-year-old girl with a history of delayed development who was diagnosed with medulloblastoma. Genetic evaluations revealed that she inherited a germline duplication of 14q22.3, which included OTX2. This genetic alteration was passed down from her mother, who also had a history of delayed development. Results from other genetic testing, including exome sequencing, fragile X syndrome, and mtDNA testing, were negative/normal. This is the second report of a 14q22.3 duplication that included OTX2 in a patient with medulloblastoma. Further studies are necessary to establish a clear association.

Non-progressive mandibular changes in children with Type I and II craniofacial microsomia

OBJECTIVE

To describe the mandibular growth of craniofacial microsomia (CFM) patients during early childhood to adolescence with attention to symmetry.

MATERIALS AND METHODS

Altogether 61 CFM patients were studied at the Cleft Palate and Craniofacial Center, Helsinki University Hospital between 1986 and 2006. In this cohort study, we measured and analysed 293 radiographs (posteroanterior, panoramic and lateral); 165 radiographs of 40 patients met the final inclusion criteria. The vertical height of the ramus in anteroposterior and panoramic radiographs, the length of the mandible in anteroposterior radiographs and the maxillary protrusion and mandibular retrognathia in lateral cephalograms were measured in four different age groups.

RESULTS

A statistical difference existed between the groups in the vertical height of the ramus and in the mandibular length. The vertical height of the ramus measured from the panoramic radiograph grew on both sides, and the ratios remained unchanged. In the sagittal dimension, the maxilla and mandible grew forward, but no significant differences emerged between the groups.

CONCLUSIONS

Results suggest that mild-type CFM is not progressive in nature. During growth, mandibular asymmetry measured in the horizontal, vertical and sagittal planes did not increase.

Transcriptome analyses of murine right and left maxilla-mandibular complex

OBJECTIVE

The objective of the study was to investigate differential gene expression between murine right and left maxilla-mandibular (MxMn) complexes.

SETTING AND SAMPLE POPULATION

Wild-type (WT) C57BL/6 embryonic (E) day 14.5 (n = 3) and 18.5 (n = 3) murine embryos.

METHODS

The E14.5 and 18.5 embryos were harvested and hemi-sectioned the MxMn complexes into right and left halves in the mid-sagittal plane. We isolated total RNA using Trizol reagent and further purified using the RNA-easy kit (QIAGEN). We confirmed equal expression of house-keeping genes in right and left halves using RT-PCR and then performed paired-end whole mRNA sequencing in LC Sciences (Houston, TX) followed by differential transcript analyses (>1 or <-1 log fold change; p < .05; q < .05; and FPKM >0.5 in 2/3 samples). The Mouse Genome Informatics and Online Mendelian Inheritance in Man databases as well as gnomAD constraint scores were used to prioritize differentially expressed transcripts.

RESULTS

There were 19 upregulated and 19 downregulated transcripts at E14.5 and 8 upregulated and 17 downregulated transcripts at E18.5 time-points. These differentially expressed transcripts were statistically significant and shown to be associated with craniofacial phenotypes in mouse models. These transcripts also have significant gnomAD constraint scores and are enriched in biological processes critical for embryogenesis.

CONCLUSIONS

We identified significant differential expression of transcripts between E14.5 and 18.5 murine right and left MxMn complexes. These findings when extrapolated to humans, they may provide a biological basis for facial asymmetry. Further experiments are required to validate these findings in murine models with craniofacial asymmetry.

Hemifacial microsomia is linked to a rare homozygous variant V162I in FRK and validated in zebrafish

OBJECTIVES

Hemifacial microsomia (HFM) is a common birth defect involving the first and second branchial arch derivatives. Although several chromosomal abnormalities and causal gene variants have been identified, genetic etiologies in a majority of cases with HFM remain unknown. This study aimed to identify genetic mutations in affected individuals with HFM.

METHODS

Whole-exome sequencing and bioinformatics analysis were performed for 16 affected individuals and their family members. Sanger sequencing was applied for confirmation of selected mutations. Zebrafish embryos were used for in situ hybridization of candidate gene, microinjection with antisense morpholino, and cartilage staining.

RESULTS

A homozygous missense mutation (c.484G > A; p.V162I) in the FRK gene was identified in an 18-year-old girl with HFM and dental abnormalities. Heterozygous mutation of this mutation was identified in her parents, who are first cousins in a consanguineous family. FRK is highly expressed in the Meckel's cartilage during embryonic development in mouse and zebrafish. Knockdown of frk in zebrafish showed a lower length and width ratio of Meckel's cartilage, abnormal mandibular jaw joint, and disorganized ceratobranchial cartilage and bone.

CONCLUSIONS

We identified a recessive variant in the FRK gene as a novel candidate gene for a patient with HFM and mandibular hypoplasia and revealed its effects on craniofacial and embryonic development in zebrafish.

A Proposal for the Classification of Temporomandibular Joint Disc Deformity in Hemifacial Microsomia

Hemifacial microsomia (HFM) is the second most common congenital craniofacial disease and has a wide spectrum of symptoms. The classic diagnostic criterion for hemifacial microsomia is the OMENS system, which was later refined to the OMENS+ system to include more anomalies. We analyzed the data of 103 HFM patients with magnetic resonance imaging (MRI) for temporomandibular joint (TMJ) discs. The TMJ disc classification was defined into four types: D0 for normal disc size and shape; D1 for disc malformation with adequate length to cover the (reconstructed) condyle; D2 for disc malformation with inadequate length to cover the (reconstructed) condyle; and D3 for no obvious presence of a disc. Additionally, this disc classification was positively correlated with the mandible classification (correlation coefficient: 0.614, p < 0.01), ear classification (correlation coefficient: 0.242, p < 0.05), soft tissue classification (correlation coefficient: 0.291, p < 0.01), and facial cleft classification (correlation coefficient: 0.320, p < 0.01). In this study, an OMENS+D diagnostic criterion is proposed, confirming the conjecture that the development of the mandibular ramus, ear, soft tissue, and TMJ disc, as homologous and adjacent tissues, is affected to a similar degree in HFM patients.

vwa1 Knockout in Zebrafish Causes Abnormal Craniofacial Chondrogenesis by Regulating FGF Pathway

Hemifacial microsomia (HFM), a rare disorder of first- and second-pharyngeal arch development, has been linked to a point mutation in VWA1 (von Willebrand factor A domain containing 1), encoding the protein WARP in a five-generation pedigree. However, how the VWA1 mutation relates to the pathogenesis of HFM is largely unknown. Here, we sought to elucidate the effects of the VWA1 mutation at the molecular level by generating a vwa1-knockout zebrafish line using CRISPR/Cas9. Mutants and crispants showed cartilage dysmorphologies, including hypoplastic Meckel’s cartilage and palatoquadrate cartilage, malformed ceratohyal with widened angle, and deformed or absent ceratobranchial cartilages. Chondrocytes exhibited a smaller size and aspect ratio and were aligned irregularly. In situ hybridization and RT-qPCR showed a decrease in barx1 and col2a1a expression, indicating abnormal cranial neural crest cell (CNCC) condensation and differentiation. CNCC proliferation and survival were also impaired in the mutants. Expression of FGF pathway components, including fgf8a, fgfr1, fgfr2, fgfr3, fgfr4, and runx2a, was decreased, implying a role for VWA1 in regulating FGF signaling. Our results demonstrate that VWA1 is essential for zebrafish chondrogenesis through effects on condensation, differentiation, proliferation, and apoptosis of CNCCs, and likely impacts chondrogenesis through regulation of the FGF pathway.

Exploration of Novel Genetic Evidence and Clinical Significance Into Hemifacial Microsomia Pathogenesis

The authors browsed through past genetic findings in hemifacial microsomia along with our previously identified mutations in ITGB4 and PDE4DIP from whole genome sequencing of hemifacial microsomia patients. Wondering whether these genes influence mandibular bone modeling by regulation on osteogenesis, the authors approached mechanisms of hemifacial microsomia through this investigation into gene knockdown effects in vitro. MC3T3E1 cells were divided into 5 groups: the negative control group without osteogenesis induction or siRNA, the positive control group with only osteogenesis induction, and 3 gene silenced groups with both osteogenesis induction and siRNA. Validation of transfection was through fluorescence microscopy and quantitative real-time Polymerase chain reaction on knockdown efficiency. Changes in expression levels of the 3 genes during osteogenesis and impact of Itgb4 and Pde4dip knockdown on osteogenesis were examined by quantitative real-time Polymerase chain reaction, alkaline phosphatase, and alizarin red staining. Elevation of osteogenic genes Alpl, Col1a1, Bglap, Spp1, and Runx2 verified successful osteogenesis. Both genes were upregulated under osteogenic induction, while they had different trends over time. Intracellular fluorophores under microscope validated successful transfection and si-m-Itgb4_003, si-m-Pde4dip_002 had satisfactory knockdown effects. During osteogenesis, Pde4dip knockdown enhanced Spp1 expression (1.95±0.13 folds, P =0.045). The authors speculated that these genes may have different involvements in osteogenesis. Stimulated expression of Spp1 by Pde4dip knockdown may suggest that Pde4dip inhibits osteogenesis.

OTX2 duplications: a recurrent cause of oculo-auriculo-vertebral spectrum

Background

Oculo-auriculo-vertebral spectrum (OAVS) is the second most common cause of head and neck malformations in children after orofacial clefts. OAVS is clinically heterogeneous and characterised by a broad range of clinical features including ear anomalies with or without hearing loss, hemifacial microsomia, orofacial clefts, ocular defects and vertebral abnormalities. Various genetic causes were associated with OAVS and copy number variations represent a recurrent cause of OAVS, but the responsible gene often remains elusive.

Methods

We described an international cohort of 17 patients, including 10 probands and 7 affected relatives, presenting with OAVS and carrying a 14q22.3 microduplication detected using chromosomal microarray analysis. For each patient, clinical data were collected using a detailed questionnaire addressed to the referring clinicians. We subsequently studied the effects ofOTX2overexpression in a zebrafish model.

Results

We defined a 272 kb minimal common region that only overlaps with theOTX2gene. Head and face defects with a predominance of ear malformations were present in 100% of patients. The variability in expressivity was significant, ranging from simple chondromas to severe microtia, even between intrafamilial cases. Heterologous overexpression ofOTX2in zebrafish embryos showed significant effects on early development with alterations in craniofacial development.

Conclusions

Our results indicate that properOTX2dosage seems to be critical for the normal development of the first and second branchial arches. Overall, we demonstrated thatOTX2genomic duplications are a recurrent cause of OAVS marked by auricular malformations of variable severity.

DNA methylation biomarkers in asthma and rhinitis: Are we there yet?

The study of epigenetics has improved our understanding of mechanisms underpinning gene‐environment interactions and is providing new insights in the pathophysiology of respiratory allergic diseases. We reviewed the literature on DNA methylation patterns across different tissues in asthma and/or rhinitis and attempted to elucidate differentially methylated loci that could be used to characterize asthma or rhinitis. Although nasal and bronchial epithelia are similar in their histological structure and cellular composition, genetic and epigenetic regulation may differ across tissues. Advanced methods have enabled comprehensive, high‐throughput methylation profiling of different tissues (bronchial or nasal epithelial cells, whole blood or isolated mononuclear cells), in subjects with respiratory conditions, aiming to elucidate gene regulation mechanisms and identify new biomarkers. Several genes and CpGs have been suggested as asthma biomarkers, though research on allergic rhinitis is still lacking. The most common differentially methylated loci presented in both blood and nasal samples are ACOT7, EPX, KCNH2, SIGLEC8, TNIK, FOXP1, ATPAF2, ZNF862, ADORA3, ARID3A, IL5RA, METRNL and ZFPM1. Overall, there is substantial variation among studies, (i.e. sample sizes, age groups and disease phenotype). Greater variability of analysis method detailed phenotypic characterization and age stratification should be taken into account in future studies.

Oculo-auriculo-vertebral spectrum: new genes and literature review on a complex disease

Oculo-auriculo-vertebral spectrum (OAVS) or Goldenhar syndrome is due to an abnormal development of first and second branchial arches derivatives during embryogenesis and is characterised by hemifacial microsomia associated with auricular, ocular and vertebral malformations. The clinical and genetic heterogeneity of this spectrum with incomplete penetrance and variable expressivity, render its molecular diagnosis difficult. Only a few recurrent CNVs and genes have been identified as causatives in this complex disorder so far. Prenatal environmental causal factors have also been hypothesised. However, most of the patients remain without aetiology. In this review, we aim at updating clinical diagnostic criteria and describing genetic and non-genetic aetiologies, animal models as well as novel diagnostic tools and surgical management, in order to help and improve clinical care and genetic counselling of these patients and their families.

Copy number variation analysis implicates novel pathways in patients with oculo-auriculo-vertebral-spectrum and congenital heart defects

Oculo-auriculo-vertebral spectrum (OAVS) is a developmental disorder of craniofacial morphogenesis. Its etiology is unclear, but assumed to be complex and heterogeneous, with contribution of both genetic and environmental factors. We assessed the occurrence of copy number variants (CNVs) in a cohort of 19 unrelated OAVS individuals with congenital heart defect. Chromosomal microarray analysis identified pathogenic CNVs in 2/19 (10.5%) individuals, and CNVs classified as variants of uncertain significance in 7/19 (36.9%) individuals. Remarkably, two subjects had small intragenic CNVs involving DACH1 and DACH2, two paralogs coding for key components of the PAX-SIX-EYA-DACH network, a transcriptional regulatory pathway controlling developmental processes relevant to OAVS and causally associated with syndromes characterized by craniofacial involvement. Moreover, a third patient showed a large duplication encompassing DMBX1/OTX3, encoding a transcriptional repressor of OTX2, another transcription factor functionally connected to the DACH-EYA-PAX network. Among the other relevant CNVs, a deletion encompassing HSD17B6, a gene connected with the retinoic acid signaling pathway, whose dysregulation has been implicated in craniofacial malformations, was also identified. Our findings suggest that CNVs affecting gene dosage likely contribute to the genetic heterogeneity of OAVS, and implicate the PAX-SIX-EYA-DACH network as novel pathway involved in the etiology of this developmental trait.

Whole-Exome Sequencing Reveals Rare Germline Mutations in Patients With Hemifacial Microsomia

Hemifacial microsomia (HFM) is a rare congenital disease characterized by a spectrum of craniomaxillofacial malformations, including unilateral hypoplasia of the mandible and surrounding structures. Genetic predisposition for HFM is evident but the causative genes have not been fully understood. Thus, in the present study, we used whole-exome sequencing to screen 52 patients with HFM for rare germline mutations. We revealed 3,341 rare germline mutations in this patient cohort, including those in 13 genes previously shown to be associated with HFM. Among these HFM-related genes, NID2 was most frequently mutated (in 3/52 patients). PED4DIP, which has not been previously associated with HFM, exhibited rare variants most frequently (in 7/52 patients). Pathway enrichment analysis of genes that were mutated in >2 patients predicted the "laminin interactions" pathway to be most significantly disrupted, predominantly by mutations in ITGB4, NID2, or LAMA5. In summary, this study is the first to identify rare germline mutations in HFM. The likely disruptions in the signaling pathways due to the mutations reported here may be considered potential causes of HFM.

Novel risk factors for craniofacial microsomia and assessment of their utility in clinic diagnosis

Craniofacial microsomia (CFM, OMIM%164 210) is one of the most common congenital facial abnormalities worldwide, but it's genetic risk factors and environmental threats are poorly investigated, as well as their interaction, making the diagnosis and prenatal screening of CFM impossible. We perform a comprehensive association study on the largest CFM cohort of 6074 samples. We identify 15 significant (P < 5 × 10-8) associated genomic loci (including eight previously reported) and decipher 107 candidates based on multi-omics data. Gene Ontology term enrichment found that these candidates are mainly enriched in neural crest cell (NCC) development and hypoxic environment. Single-cell RNA-seq data of mouse embryo demonstrate that nine of them show dramatic expression change during early cranial NCC development whose dysplasia is involved in pathogeny of CFM. Furthermore, we construct a well-performed CFM risk-predicting model based on polygenic risk score (PRS) method and estimate seven environmental risk factors that interacting with PRS. Single-nucleotide polymorphism-based PRS is significantly associated with CFM [P = 7.22 × 10-58, odds ratio = 3.15, 95% confidence interval (CI) 2.74-3.63], and the top fifth percentile has a 6.8-fold CFM risk comparing with the 10th percentile. Father's smoking increases CFM risk as evidenced by interaction parameter of -0.324 (95% CI -0.578 to -0.070, P = 0.011) with PRS. In conclusion, the newly identified risk loci will significantly improve our understandings of genetics contribution to CFM. The risk prediction model is promising for CFM prediction, and father's smoking is a key environmental risk factor for CFM through interacting with genetic factors.

A recurrent missense variant in EYA3 gene is associated with oculo-auriculo-vertebral spectrum

Goldenhar syndrome or oculo-auriculo-vertebral spectrum (OAVS) is a complex developmental disorder characterized by asymmetric ear anomalies, hemifacial microsomia, ocular and vertebral defects. We aimed at identifying and characterizing a new gene associated with OAVS. Two affected brothers with OAVS were analyzed by exome sequencing that revealed a missense variant (p.(Asn358Ser)) in the EYA3 gene. EYA3 screening was then performed in 122 OAVS patients that identified the same variant in one individual from an unrelated family. Segregation assessment in both families showed incomplete penetrance and variable expressivity. We investigated this variant in cellular models to determine its pathogenicity and demonstrated an increased half-life of the mutated protein without impact on its ability to dephosphorylate H2AFX following DNA repair pathway induction. Proteomics performed on this cellular model revealed four significantly predicted upstream regulators which are PPARGC1B, YAP1, NFE2L2 and MYC. Moreover, eya3 knocked-down zebrafish embryos developed specific craniofacial abnormalities corroborating previous animal models and supporting its involvement in the OAVS. Additionally, EYA3 gene expression was deregulated in vitro by retinoic acid exposure. EYA3 is the second recurrent gene identified to be associated with OAVS. Moreover, based on protein interactions and related diseases, we suggest the DNA repair as a key molecular pathway involved in craniofacial development.

Three-Dimensional Planning of the Mandibular Margin in Hemifacial Microsomia Using a Printed Patient-Specific Implant

Hemifacial microsomia (HFM) is also known as malformation of the first and second branchial arches (BAs), oculoauriculovertebral dysplasia syndrome, and Goldenhar syndrome. Possibilities resulting from CAD/CAM may be a valuable tool to existing procedures to treat these abnormalities. The aim of this study was to report a case where the planning and implementation of an intraorally inserted 2-part patient-specific mandible implant was used for the treatment of HFM esthetic remained problem after orthognathic surgery. A 20-year-old female patient who continued to suffer from the esthetic defect of the unilateral hypoplastic mandible after completion of the orthognathic surgery attended for consultation. Using CT scan and the software Geomagic Freeform (3D Systems, USA), a 2-piece titanium implant was designed and printed to restore the osseous frame of the basal border of the mandible. The base was made of solid polished titanium to minimize soft tissue abrasion. Due to its split design, the implant could be placed anatomically exactly at the mandibular margin via an intraoral access and to avoid damage of the mental nerve. There were no postoperative complications such as infections, soft tissue reactions to the implant, sensitivity disorders, or dehiscence. The occlusion was regular. A measurement of the postoperative x-rays showed a clear increase in bony symmetry. No postoperative pain or trismus was seen. Functionally, the therapy ended with the completion of wound healing and the jaw was fully resilient again. A combined treatment using PSI and additional autogenous fat grafting may represent a valid treatment option for the treatment of facial asymmetry in patients with HFM.

Microarray-Based Comparative Genomic Hybridization, Multiplex Ligation-Dependent Probe Amplification, and High-Resolution Karyotype for Differential Diagnosis Oculoauriculovertebral Spectrum: A Systematic Review

Oculoauriculovertebral spectrum (OAVS) is a rare class of heterogenous congenital craniofacial malformation conditions of unknown etiology. Although classic OAVS has been described as hemifacial microsomia with facial asymmetry and microtia, there is no consensus regarding clinical criteria for diagnosis or genetic cause. This systematic review aims to assess the applicability of high-resolution (HR) karyotype, fluorescence in situ hybridization, multiplex ligation-dependent probe amplification (MLPA), and microarray-based comparative genomic hybridization (array-CGH) for differential diagnosis of OAVS. A search was performed in PubMed and Web of Science using all entry terms to the following descriptors: Goldenhar's syndrome, cytogenetic analysis, hybridization in situ, fluorescent, comparative genomic hybridization, multiplex polymerase chain reaction, whole genome sequencing, and karyotype analysis methods. After screening, 25 articles met eligibility. Of the included studies, 59 individuals had a genetic alteration identified. Array-CGH, MLPA, and HR karyotype appear to be viable approaches for molecular diagnosis in OAVS. Heterogeneity is a hallmark of OAVS. Establishing an enhanced framework for diagnosis would inform clinical decision making, and better resource utilization could improve health care facility efficiency and economy.

SPECC1L regulates palate development downstream of IRF6

SPECC1L mutations have been identified in patients with rare atypical orofacial clefts and with syndromic cleft lip and/or palate (CL/P). These mutations cluster in the second coiled-coil and calponin homology domains of SPECC1L and severely affect the ability of SPECC1L to associate with microtubules. We previously showed that gene-trap knockout of Specc1l in mouse results in early embryonic lethality. We now present a truncation mutant mouse allele, Specc1lΔC510, that results in perinatal lethality. Specc1lΔC510/ΔC510 homozygotes showed abnormal palate rugae but did not show cleft palate. However, when crossed with a gene-trap allele, Specc1lcGT/ΔC510 compound heterozygotes showed a palate elevation delay with incompletely penetrant cleft palate. Specc1lcGT/ΔC510 embryos exhibit transient oral epithelial adhesions at E13.5, which may delay shelf elevation. Consistent with oral adhesions, we show periderm layer abnormalities, including ectopic apical expression of adherens junction markers, similar to Irf6 hypomorphic mutants and Arhgap29 heterozygotes. Indeed, SPECC1L expression is drastically reduced in Irf6 mutant palatal shelves. Finally, we wanted to determine if SPECC1L deficiency also contributed to non-syndromic (ns) CL/P. We sequenced 62 Caucasian, 89 Filipino, 90 Ethiopian, 90 Nigerian and 95 Japanese patients with nsCL/P and identified three rare coding variants (p.Ala86Thr, p.Met91Iso and p.Arg546Gln) in six individuals. These variants reside outside of SPECC1L coiled-coil domains and result in milder functional defects than variants associated with syndromic clefting. Together, our data indicate that palate elevation is sensitive to deficiency of SPECC1L dosage and function and that SPECC1L cytoskeletal protein functions downstream of IRF6 in palatogenesis.

A novel nonsense substitution identified in the AMIGO2 gene in an Occulo-Auriculo-Vertebral spectrum patient

OBJECTIVE

Craniofacial microsmia is the second most common congenital disorder with mostly unilateral defects of ear, temporomandibular joint, mandible, and muscles of facial expression and mastication. The objective of this study was to identify, if there were any, de novo germline or somatic variants in a patient with Occulo-Auriculo-Vertebral Spectrum (OAVS) using whole-exome sequencing.

SETTINGS AND SAMPLE POPULATION

Trio/Family-based study of an OAVS proband.

MATERIALS AND METHODS

Children's Mercy Hospital Institutional Review Board approved this study and a request-to-rely was procured from the University of Missouri Kansas City IRB. Informed assent/consent was obtained for all family members prior to any research activities. The peripheral blood/affected side tissues from corrective surgery of the proband and peripheral blood samples from unaffected parents were collected. The isolated genomic DNA were enriched for exomes and sequenced on an Illlumina HiSeq 2500 instrument yielding paired-end 125 nucleotide reads (84X coverage). Gapped alignment to reference sequences (GRCh37.p5) was performed with BWA and the GATK and analysis completed using custom-developed software.

RESULTS

Analyses revealed that the proband carried a de novo germ line nonsense substitution (c.901C>T) in AMIGO2 gene, and missense substitutions in ZCCHC14 (c.1198C>T), and in SZT2 genes (c.2951C>T).

CONCLUSIONS

The nonsense substitution in AMIGO2 gene introduces a premature stop codon possibly rendering the gene non-functional via nonsense-mediated pathway decay-therefore considered a stronger candidate. Further functional studies are required to confirm whether loss-of-function variants in AMIGO2 can cause OAVS.

The co-occurrence of rare non-ocular phenotypes in patients with inherited retinal degenerations

Purpose

To describe the coexistence of additional non-ocular genetic diseases in patients diagnosed with inherited retinal degenerations (IRDs).

Methods

The study was based on a retrospective chart review of patients diagnosed with IRD and additional rare systemic diseases. The chart review included the ophthalmic and genetic aspects of each patient. The ophthalmic examination included best-corrected visual acuity, biomicroscopic examination, cycloplegic refraction, retinal imaging (fundus photos, optical coherence tomography, and fundus autofluorescence), and electroretinography. Genetic testing included homozygosity mapping, whole exome sequencing, and Sanger sequencing.

Results

Fifteen index cases diagnosed with IRDs and one or more rare systemic diseases were identified. Six of the families were consanguineous. Of six patients with complete molecular diagnosis, four (66%) had pathogenic variants in two autosomal recessive (AR) disease genes, and of the total pathogenic variants identified, AR mutations were the most common (16/22, 72%). One patient was diagnosed with mutations in three different genes, underlying three distinct genetic conditions. Nine patients could have had an incorrect clinical diagnosis based on the clinical evaluation only (e.g., retinitis pigmentosa and hearing loss could have been diagnosed as Usher syndrome).

Conclusions

The common working paradigm for the ophthalmologist is combining the different symptoms observed in a patient into one unifying diagnosis. However, IRD is a strikingly heterogeneous condition, and may coincide with other genetic (and non-genetic) rare conditions. Establishing a correct diagnosis is important for the patients and their family members, as it enables prediction of disease prognosis, aids in tailoring the correct follow-up and treatment, and allows patients to pursue prenatal counseling and reproductive planning.

Rare single-nucleotide variants in oculo-auriculo-vertebral spectrum (OAVS)

Background

Oculo‐auriculo‐vertebral spectrum (OAVS) is a craniofacial developmental disorder that affects structures derived from the first and second pharyngeal arches. The clinically heterogeneous phenotype involves mandibular, oral, and ear development anomalies. Etiology is complex and poorly understood. Genetic factors have been associated, evidenced by chromosomal abnormalities affecting different genomic regions and genes. However, known pathogenic single‐nucleotide variants (SNVs) have only been identified in MYT1 in a restricted number of patients. Therefore, investigations of SNVs on candidate genes may reveal other pathogenic mechanisms.

Methods

In a cohort of 73 patients, coding and untranslated regions (UTR) of 10 candidate genes (CRKL, YPEL1, MAPK1, NKX3‐2, HMX1, MYT1, OTX2, GSC, PUF60, HOXA2) were sequenced. Rare SNVs were selected and in silico predictions were performed to ascertain pathogenicity. Likely pathogenic variants were validated by Sanger sequencing and heritability was assessed when possible.

Results

Four likely pathogenic variants in heterozygous state were identified in different patients. Two SNVs were located in the 5’UTR of YPEL1; one in the 3’UTR of CRKL and one in the 3’UTR of OTX2.

Conclusion

Our work described variants in candidate genes for OAVS and supported the genetic heterogeneity of the spectrum.

Volumetric characteristics of prognathic mandible revealed by skeletal unit analysis

The purpose of this study was to evaluate the skeletal units of a normal mandible (class I) and a prognathic mandible (class III), to compare the groups, and to investigate the key functional unit responsible for mandibular prognathism. Hemi-mandibles of 101 cases were evaluated by cone-beam computed tomography. Of these, 50 cases had Class I and 51 had Class III mandibles. The length, volume, and volume/length ratio of each skeletal unit were measured. The ratios of the condyle, body unit, and sum of the hemi-mandible between Class I and Class III showed statistically significant results (P<0.05). However, the ratios of angle, coronoid, and symphysis units did not show any statistical significance on comparison. Dependent on gender, in males the ratio of the condyle of the hemi-mandible showed statistically significant results (P<0.05). Meanwhile in females the ratio of the body and sum of the hemi-mandible showed statistically significant results (P<0.05). Accordingly, the mandibular body and condylar units are thinner in mandibular prognathism. On the basis of the functional matrix theory to determine the aetiology of mandibular prognathism, the key skeletal units are the body and condylar units.

Craniofacial Microsomia

Clinicians use different diagnostic terms for patients with underdevelopment of facial features arising from the embryonic first and second pharyngeal arches, including first and second branchial arch syndrome, otomandibular dysostosis, oculoauriculovertebral syndrome, and hemifacial microsomia. Craniofacial microsomia has become the preferred term. Although no diagnostic criteria for craniofacial microsomia exist, most patients have a degree of underdevelopment of the mandible, maxilla, ear, orbit, facial soft tissue, and/or facial nerve. These anomalies can affect feeding, compromise the airway, alter facial movement, disrupt hearing, and alter facial appearance.

Etiology and Pathogenesis of Hemifacial Microsomia

Hemifacial microsomia (HFM) is a common congenital malformation of the craniofacial region. There are 3 possible pathogenic models of HFM—vascular abnormality and hemorrhage in the craniofacial region, damage to Meckel’s cartilage, and the abnormal development of cranial neural crest cells—and the most plausible hypothesis is the vascular abnormality and hemorrhage model. These 3 models are interrelated, and none of them is completely concordant with all the variable manifestations of HFM. External environmental factors (e.g., thalidomide, triazene, retinoic acid, and vasoactive medications), maternal intrinsic factors (e.g., maternal diabetes), and genetic factors (e.g., the recently reported mutations in OTX2, PLCD3, and MYT1) may lead to HFM through ≥1 of these pathogenic processes. Whole genome sequencing to identify additional pathogenic variants, biological functional studies to understand the exact molecular mechanisms, and additional animal model and clinical studies with large stratified samples to elucidate the pathogenesis of HFM will be necessary. Small-molecule drugs, as well as CRISPR/CAS9-based genetic interventions, for the prevention and treatment of HFM may also be a future research hotspot.

Whole-exome sequencing identified a variant in EFTUD2 gene in establishing a genetic diagnosis

OBJECTIVES

Craniofacial anomalies are complex and have an overlapping phenotype. Mandibulofacial Dysostosis and Oculo-Auriculo-Vertebral Spectrum are conditions that share common craniofacial phenotype and present a challenge in arriving at a diagnosis. In this report, we present a case of female proband who was given a differential diagnosis of Treacher Collins syndrome or Hemifacial Microsomia without certainty. Prior genetic testing reported negative for 22q deletion and FGFR screenings. The objective of this study was to demonstrate the critical role of whole-exome sequencing in establishing a genetic diagnosis of the proband.

SETTING AND SAMPLE POPULATION

The participants were 14½-year-old affected female proband/parent trio.

MATERIALS AND METHODS

Proband/parent trio were enrolled in the study. Surgical tissue sample from the proband and parental blood samples were collected and prepared for whole-exome sequencing. Illumina HiSeq 2500 instrument was used for sequencing (125 nucleotide reads/84X coverage). Analyses of variants were performed using custom-developed software, RUNES and VIKING.

RESULTS

Variant analyses following whole-exome sequencing identified a heterozygous de novo pathogenic variant, c.259C>T (p.Gln87*), in EFTUD2 (NM_004247.3) gene in the proband. Previous studies have reported that the variants in EFTUD2 gene were associated with Mandibulofacial Dysostosis with Microcephaly.

CONCLUSION

Patients with facial asymmetry, micrognathia, choanal atresia and microcephaly should be analyzed for variants in EFTUD2 gene. Next-generation sequencing techniques, such as whole-exome sequencing offer great promise to improve the understanding of etiologies of sporadic genetic diseases.

Genomic associations with bill length and disease reveal drift and selection across island bird populations

Island species provide excellent models for investigating how selection and drift operate in wild populations, and for determining how these processes act to influence local adaptation and speciation. Here, we examine the role of selection and drift in shaping genomic and phenotypic variation across recently separated populations of Berthelot's pipit (Anthus berthelotii), a passerine bird endemic to three archipelagos in the Atlantic. We first characterized genetic diversity and population structuring that supported previous inferences of a history of recent colonizations and bottlenecks. We then tested for regions of the genome associated with the ecologically important traits of bill length and malaria infection, both of which vary substantially across populations in this species. We identified a SNP associated with variation in bill length among individuals, islands, and archipelagos; patterns of variation at this SNP suggest that both phenotypic and genotypic variation in bill length is largely shaped by founder effects. Malaria was associated with SNPs near/within genes involved in the immune response, but this relationship was not consistent among archipelagos, supporting the view that disease resistance is complex and rapidly evolving. Although we found little evidence for divergent selection at candidate loci for bill length and malaria resistance, genome scan analyses pointed to several genes related to immunity and metabolism as having important roles in divergence and adaptation. Our findings highlight the utility and challenges involved with combining association mapping and population genetic analysis in nonequilibrium populations, to disentangle the effects of drift and selection on shaping genotypes and phenotypes.

Haploinsufficiency of BMP4 and OTX2 in the Foetus with an abnormal facial profile detected in the first trimester of pregnancy

Background

Interstitial microdeletion 14q22q23 is a rare chromosomal syndrome associated with variable defects: microphthalmia/anophthalmia, pituitary anomalies, polydactyly/syndactyly of hands and feet, micrognathia/retrognathia. The reports of the microdeletion 14q22q23 detected in the prenatal stages are limited and the range of clinical features reveals a quite high variability.

Case presentation

We report a detection of the microdeletion 14q22.1q23.1 spanning 7,7 Mb and involving the genes BMP4 and OTX2 in the foetus by multiplex ligation-dependent probe amplification (MLPA) and verified by microarray subsequently. The pregnancy was referred to the genetic counselling for abnormal facial profile observed in the first trimester ultrasound scan and micrognathia (suspicion of Pierre Robin sequence), hypoplasia nasal bone and polydactyly in the second trimester ultrasound scan. The pregnancy was terminated on request of the parents.

Conclusion

An abnormal facial profile detected on prenatal scan can provide a clue to the presence of rare chromosomal abnormalities in the first trimester of pregnancy despite the normal result of the first trimester screening test. The patients should be provided with genetic counselling. Usage of quick and sensitive methods (MLPA, microarray) is preferable for discovering a causal aberration because some of the CNVs cannot be detected with conventional karyotyping in these cases. To the best of our knowledge, this is the earliest detection of this microdeletion (occurred de novo), the first case detected by MLPA and confirmed by microarray. Literature review of the genotype-phenotype correlation in similar reports leads us to the conclusion that dosage imbalance of the chromosomal segment 14q22q23 (especially haploinsuffiency of the genes BMP4 and OTX2) contributes significantly to orofacial abnormalities. Association of the region with the Pierre Robin sequence appears to be plausible.

Update on 13 Syndromes Affecting Craniofacial and Dental Structures

Care of individuals with syndromes affecting craniofacial and dental structures are mostly treated by an interdisciplinary team from early childhood on. In addition to medical and dental specialists that have a vivid interest in these syndromes and for whom these syndromes are of evident interest, experts of scientific background-like molecular and developmental geneticists, but also computational biologists and bioinformaticians-, become more frequently involved in the refined diagnostic and etiological processes of these patients. Early diagnosis is often crucial for the effective treatment of functional and developmental aspects. However, not all syndromes can be clinically identified early, especially in cases of absence of known family history. Moreover, the treatment of these patients is often complicated because of insufficient medical knowledge, and because of the dental and craniofacial developmental variations. The role of the team is crucial for the prevention, proper function, and craniofacial development which is often combined with orthognathic surgery. Although the existing literature does not provide considerable insight into this topic, this descriptive review aims to provide tools for the interdisciplinary team by giving an update on the genetics and general features, and the oral and craniofacial manifestations for early diagnosis. Clinical phenotyping together with genetic data and pathway information will ultimately pave the way for preventive strategies and therapeutic options in the future. This will improve the prognosis for better functional and aesthetic outcome for these patients and lead to a better quality of life, not only for the patients themselves but also for their families. The aim of this review is to promote interdisciplinary interaction and mutual understanding among all specialists involved in the diagnosis and therapeutic guidance of patients with these syndromal conditions in order to provide optimal personalized care in an integrated approach.

Nasal DNA methylation differentiates corticosteroid treatment response in pediatric asthma: A pilot study

BACKGROUND

Treatment response to systemic corticosteroid in asthmatic children is heterogeneous and may be mediated by epigenetic mechanism(s). We aim to identify DNA methylation (DNAm) changes responsive to steroid, and DNAm biomarkers that distinguish treatment response.

MATERIALS AND METHODS

We followed 33 children (ages 5-18) presenting to the Emergency Department (ED) for asthma exacerbation. Based on whether they met discharge criteria in ≤24 hours, participants were grouped into good and poor responders to steroid treatment. Nasal samples were collected upon presentation to the ED (T0) and 18-24 hours later (T1). Genome-wide DNAm was measured for both time points in 20 subjects, and compared between T0 and T1 in good and poor responders respectively. DNAm at T1 was also compared between two responder groups. DNAm of selected CpGs was verified in the complete cohort, and expression of associated genes was examined. Interactions between DNAm, common single nucleotide polymorphism (SNP) located at the CpG sites and treatment responses were assessed.

RESULTS

Three CpGs located in the OTX2 promoter showed responder-specific DNAm changes from T0 to T1, in which DNAm decreased in good but not in poor responders. Good and poor responders showed differential DNAm at T1 in 127 CpGs without and 182 CpGs with common SNP co-localization. Negative correlations between DNAm and gene expression were observed at CpGs located within the LDHC promoter, suggesting an impact of DNAm on gene regulation. Interactions between SNPs, DNAm and treatment response were detected.

CONCLUSION

Acute systemic steroid treatment modifies nasal DNAm in good responders. Nasal DNAm, dependent or independent of SNPs, can differentiate response to treatment in acute asthmatic children.

Maxillofacial features and systemic malformations in expanded spectrum Hemifacial Microsomia

Hemifacial microsomia (HFM) is a rare, multisystemic congenital disease with estimated frequency of 1/26370 births in Europe. Most cases are sporadic and caused by unilateral abnormal morphogenesis of the first and second pharyngeal arches. The aim of this study is to define the types and frequency of maxillofacial and systemic malformations in HFM patients. This is a case series study of patients with HFM evaluated at a single institution. Data were acquired through history, physical examination, photographs, diagnostic radiology, and laboratory and analyzed by the FileMakerPro database on 95 patients (54F; 41M) of which 89 met the inclusion criteria. Mandibular hypoplasia was observed in 86 patients with right-side preponderance (50). One patient had bilateral mandibular hypoplasia. Seventy-four had external ear anomalies (anotia or microtia). Eleven had bilateral malformed ears. Hearing impairment, associated with stenosis or atresia of the external ear canal, was found in 69 patients (eight with bilateral canal defects). Ocular anomalies were seen in 41 (23 with dermoid cysts) and 39 had orbital malformations. Facial nerve paralysis was observed in 38 patients. Cleft lip/palate (10), preauricular tags (55), and macrostomia (41) were also described. A total of 73/86 had systemic malformations, mainly vertebral (40), genitourinary (25), and cardiovascular (28). Sixteen had cerebral anomalies (four with intellectual disability). All patients suspected of HFM should undergo a complete systematic clinical and imaging investigation to define the full scope of anomalies. Since the disease is rare and complex, affected patients should be monitored by specialized multidisciplinary team centers.

Genetics of Combined Pituitary Hormone Deficiency: Roadmap into the Genome Era

The genetic basis for combined pituitary hormone deficiency (CPHD) is complex, involving 30 genes in a variety of syndromic and nonsyndromic presentations. Molecular diagnosis of this disorder is valuable for predicting disease progression, avoiding unnecessary surgery, and family planning. We expect that the application of high throughput sequencing will uncover additional contributing genes and eventually become a valuable tool for molecular diagnosis. For example, in the last 3 years, six new genes have been implicated in CPHD using whole-exome sequencing. In this review, we present a historical perspective on gene discovery for CPHD and predict approaches that may facilitate future gene identification projects conducted by clinicians and basic scientists. Guidelines for systematic reporting of genetic variants and assigning causality are emerging. We apply these guidelines retrospectively to reports of the genetic basis of CPHD and summarize modes of inheritance and penetrance for each of the known genes. In recent years, there have been great improvements in databases of genetic information for diverse populations. Some issues remain that make molecular diagnosis challenging in some cases. These include the inherent genetic complexity of this disorder, technical challenges like uneven coverage, differing results from variant calling and interpretation pipelines, the number of tolerated genetic alterations, and imperfect methods for predicting pathogenicity. We discuss approaches for future research in the genetics of CPHD.

Candidate gene prioritization with Endeavour

Genomic studies and high-throughput experiments often produce large lists of candidate genes among which only a small fraction are truly relevant to the disease, phenotype or biological process of interest. Gene prioritization tackles this problem by ranking candidate genes by profiling candidates across multiple genomic data sources and integrating this heterogeneous information into a global ranking. We describe an extended version of our gene prioritization method, Endeavour, now available for six species and integrating 75 data sources. The performance (Area Under the Curve) of Endeavour on cross-validation benchmarks using ‘gold standard’ gene sets varies from 88% (for human phenotypes) to 95% (for worm gene function). In addition, we have also validated our approach using a time-stamped benchmark derived from the Human Phenotype Ontology, which provides a setting close to prospective validation. With this benchmark, using 3854 novel gene–phenotype associations, we observe a performance of 82%. Altogether, our results indicate that this extended version of Endeavour efficiently prioritizes candidate genes. The Endeavour web server is freely available at https://endeavour.esat.kuleuven.be/.

Agnathia-otocephaly complex and asymmetric velopharyngeal insufficiency due to an in-frame duplication in OTX2

Agnathia-otocephaly complex is a malformation characterized by absent/hypoplastic mandible and abnormally positioned ears. Mutations in two genes, PRRX1 and OTX2, have been described in a small number of families with this disorder. We performed clinical and genetic testing in an additional family. The proband is a healthy female with a complicated pregnancy history that includes two offspring diagnosed with agnathia-otocephaly during prenatal ultrasound scans. Exome sequencing was performed in fetal DNA from one of these two offspring revealing a heterozygous duplication in OTX2: c.271_273dupCAG, p.(Gln91dup). This change leads to the insertion of a glutamine within the OTX2 homeodomain region, and is predicted to alter this signaling molecule's ability to interact with DNA. The same variant was also identified in the proband's clinically unaffected 38-year-old husband and their 9-year-old daughter, who presented with a small mandible, normal ears and velopharyngeal insufficiency due to a short hemi-palate. This unusual presentation of OTX2-related disease suggests that OTX2 might have a role in palatal hypoplasia cases. A previously unreported OTX2 variant associated with extreme intrafamilial variability is described and the utility of exome sequencing as a tool to confirm the diagnosis of agnathia-otocephaly and to inform the reproductive decisions of affected families is highlighted.