A Novel Macroglossia Severity Index for Beckwith-Wiedemann Syndrome.

OBJECTIVE/ SUMMARY BACKGROUND DATA: We propose the first classification scheme for macroglossia in patients with Beckwith-Wiedemann Syndrome (BWS), the BWS Index of macroGlossia (BIG). METHODS: Patients with molecularly confirmed BWS seen from 2004-2023 were included to develop this system. Relationships among BIG scores, tongue reduction surgery, BWS clinical score, percent mosaicism, and polysomnography findings were examined. RESULTS: Patients were classified from BIG0 to BIG3. BIG0 includes those without macroglossia; BIG1 includes those with macroglossia not protruding beyond the teeth/alveolus; BIG2 includes those with tongue protrusion past the teeth/alveolus to the lips but that can be contained within the mouth; and BIG3 includes those with tongues that protrude beyond the teeth/alveolus and lips but that cannot be closed within the mouth. Of the 459 patients with molecularly confirmed BWS, 266 (58.0%) patients were scored. One hundred and eleven (41.7%) were BIG0, 44 (16.5%) were BIG1, 90 (33.8%) were BIG2, and 21 (7.9%) were BIG3. As scores increased, patients had an increased incidence of tongue reduction surgery (BIG0: 0% versus BIG1: 20.5% versus BIG2: 51.1% versus BIG3: 100%; r=0.66, P <0.01). Higher BIG scores were associated with elevated BWS clinical scores (r=0.68, P <0.01) and increased tissue mosaicism (r=0.50, P <0.01) as well as trends towards worse obstructive apnea-hypopnea indices (r=0.29, P =0.02) and lower SpO 2 nadirs (r=-0.29, P =0.02). CONCLUSION: In this large series of patients with Beckwith-Wiedemann Syndrome, increased BIG score correlates with undergoing tongue reduction surgery and increased phenotypic severity. Adoption of the BIG scoring system may facilitate communication and risk stratification across institutions.

An Irf6-Esrp1/2 regulatory axis controls midface morphogenesis in vertebrates.

Irf6 and Esrp1 are important for palate development across vertebrates. In zebrafish, we found that irf6 regulates the expression of esrp1 We detailed overlapping Irf6 and Esrp1/2 expression in mouse orofacial epithelium. In zebrafish, irf6 and esrp1/2 share expression in periderm, frontonasal ectoderm and oral epithelium. Genetic disruption of irf6 and esrp1/2 in zebrafish resulted in cleft of the anterior neurocranium. The esrp1/2 mutant also developed cleft of the mouth opening. Lineage tracing of cranial neural crest cells revealed that the cleft resulted not from migration defect, but from impaired chondrogenesis. Analysis of aberrant cells within the cleft revealed expression of sox10, col1a1 and irf6, and these cells were adjacent to krt4+ and krt5+ cells. Breeding of mouse Irf6; Esrp1; Esrp2 compound mutants suggested genetic interaction, as the triple homozygote and the Irf6; Esrp1 double homozygote were not observed. Further, Irf6 heterozygosity reduced Esrp1/2 cleft severity. These studies highlight the complementary analysis of Irf6 and Esrp1/2 in mouse and zebrafish, and identify a unique aberrant cell population in zebrafish expressing sox10, col1a1 and irf6 Future work characterizing this cell population will yield additional insight into cleft pathogenesis.

FaceBase 3: analytical tools and FAIR resources for craniofacial and dental research.

The FaceBase Consortium was established by the National Institute of Dental and Craniofacial Research in 2009 as a 'big data' resource for the craniofacial research community. Over the past decade, researchers have deposited hundreds of annotated and curated datasets on both normal and disordered craniofacial development in FaceBase, all freely available to the research community on the FaceBase Hub website. The Hub has developed numerous visualization and analysis tools designed to promote integration of multidisciplinary data while remaining dedicated to the FAIR principles of data management (findability, accessibility, interoperability and reusability) and providing a faceted search infrastructure for locating desired data efficiently. Summaries of the datasets generated by the FaceBase projects from 2014 to 2019 are provided here. FaceBase 3 now welcomes contributions of data on craniofacial and dental development in humans, model organisms and cell lines. Collectively, the FaceBase Consortium, along with other NIH-supported data resources, provide a continuously growing, dynamic and current resource for the scientific community while improving data reproducibility and fulfilling data sharing requirements.

Roles of Wnt pathway genes wls, wnt9a, wnt5b, frzb and gpc4 in regulating convergent-extension during zebrafish palate morphogenesis.

The Wnt signaling pathway is crucial for tissue morphogenesis, participating in cellular behavior changes, notably during the process of convergent-extension. Interactions between Wnt-secreting and receiving cells during convergent-extension remain elusive. We investigated the role and genetic interactions of Wnt ligands and their trafficking factors Wls, Gpc4 and Frzb in the context of palate morphogenesis in zebrafish. We describe that the chaperon Wls and its ligands Wnt9a and Wnt5b are expressed in the ectoderm, whereas juxtaposed chondrocytes express Frzb and Gpc4. Using wls, gpc4, frzb, wnt9a and wnt5b mutants, we genetically dissected the Wnt signals operating between secreting ectoderm and receiving chondrocytes. Our analysis delineates that non-canonical Wnt signaling is required for cell intercalation, and that wnt5b and wnt9a are required for palate extension in the anteroposterior and transverse axes, respectively.

Distinct requirements of wls, wnt9a, wnt5b and gpc4 in regulating chondrocyte maturation and timing of endochondral ossification.

Formation of the mandible requires progressive morphologic change, proliferation, differentiation and organization of chondrocytes preceding osteogenesis. The Wnt signaling pathway is involved in regulating bone development and maintenance. Chondrocytes that are fated to become bone require Wnt to polarize and orientate appropriately to initiate the endochondral ossification program. Although the canonical Wnt signaling has been well studied in the context of bone development, the effects of non-canonical Wnt signaling in regulating the timing of cartilage maturation and subsequent bone formation in shaping ventral craniofacial structure is not fully understood.. Here we examined the role of the non-canonical Wnt signaling pathway (wls, gpc4, wnt5b and wnt9a) in regulating zebrafish Meckel's cartilage maturation to the onset of osteogenic differentiation. We found that disruption of wls resulted in a significant loss of craniofacial bone, whereas lack of gpc4, wnt5b and wnt9a resulted in severely delayed endochondral ossification. This study demonstrates the importance of the non-canonical Wnt pathway in regulating coordinated ventral cartilage morphogenesis and ossification.

Distinct requirements for wnt9a and irf6 in extension and integration mechanisms during zebrafish palate morphogenesis.

Development of the palate in vertebrates involves cranial neural crest migration, convergence of facial prominences and extension of the cartilaginous framework. Dysregulation of palatogenesis results in orofacial clefts, which represent the most common structural birth defects. Detailed analysis of zebrafish palatogenesis revealed distinct mechanisms of palatal morphogenesis: extension, proliferation and integration. We show that wnt9a is required for palatal extension, wherein the chondrocytes form a proliferative front, undergo morphological change and intercalate to form the ethmoid plate. Meanwhile, irf6 is required specifically for integration of facial prominences along a V-shaped seam. This work presents a mechanistic analysis of palate morphogenesis in a clinically relevant context.

Requirement for frzb and fzd7a in cranial neural crest convergence and extension mechanisms during zebrafish palate and jaw morphogenesis.

Regulation of convergence and extension by wnt-frizzled signaling is a common theme in embryogenesis. This study examines the functional requirements of frzb and fzd7a in convergence and extension mechanisms during craniofacial development. Using a morpholino knockdown approach, we found that frzb and fzd7a are dispensable for directed migration of the bilateral trabeculae, but necessary for the convergence and extension of the palatal elements, where the extension process is mediated by chondrocyte proliferation, morphologic change and intercalation. In contrast, frzb and fzd7a are required for convergence of the mandibular prominences, where knockdown of either frzb or fzd7a resulted in complete loss of lower jaw structures. Further, we found that bapx1 was specifically downregulated in the wnt9a/frzb/fzd7a morphants, while general neural crest markers were unaffected. In addition, expression of wnt9a and frzb was also absent in the edn-/- mutant. Notably, over-expression of bapx1 was sufficient to partially rescue mandibular elements in the wnt9a/frzb/fzd7a morphants, demonstrating genetic epistasis of bapx1 acting downstream of edn1 and wnt9a/frzb/fzd7a in lower jaw development. This study underscores the important role of wnt-frizzled signaling in convergence and extension in palate and craniofacial morphogenesis, distinct regulation of upper vs. lower jaw structures, and integration of wnt-frizzled with endothelin signaling to coordinate shaping of the facial form.

Associations between the timing of tongue reduction surgery, (Epi)genotype, and dentoskeletal development in patients with Beckwith-Wiedemann syndrome.

Tongue reduction surgery is often pursued to manage the adverse effects of macroglossia in patients with Beckwith-Wiedemann syndrome (BWS). This study characterized dental outcomes in patients with BWS based on surgical timing and molecular diagnosis. A retrospective study was designed to include patients with BWS over the age of two who had clinical or radiographic documentation of dental development. Patients were grouped by history of tongue reduction surgery and surgical timing (early: <12 months). One hundred three patients were included (55 no tongue reduction, 18 early, 30 late). Patients who underwent late surgery had lower odds of class I occlusion (OR 0.11, 95% CI 0.02-0.58, p = 0.009) and higher odds of anterior open bite (OR 7.5, 95% CI 1.14-49.4, p = 0.036). Patients with clinical diagnoses and negative molecular testing had anterior open bite less frequently than patients with imprinting center 2 loss of methylation and paternal uniparental isodisomy of 11p15.5 (p = 0.009). Compared to reference values, patients who had tongue reductions had an increased mandibular plane angle (32.0 ± 4.5° versus 36.9 ± 5.0°, p = 0.001), indicative of hyperdivergent growth. The results of this study help to understand the complex nature of dentoskeletal growth in BWS and shed insight on how surgical timing and molecular diagnosis influence prognosis.

Embryonic fate map of first pharyngeal arch structures in the sox10: kaede zebrafish transgenic model.

Cranial neural crest cells follow stereotypic patterns of migration to form craniofacial structures. The zebrafish is a powerful vertebrate genetic model where transgenics with reporter proteins under the transcriptional regulation of lineage-specific promoters can be generated. Numerous studies demonstrate that the zebrafish ethmoid plate is embryologically analogous to the mammalian palate. A fate map correlating embryonic cranial neural crest to defined jaw structures would provide a useful context for the morphogenetic analysis of craniofacial development. To that end, the sox10:kaede transgenic was generated, where sox10 provides lineage restriction to the neural crest. Specific regions of neural crest were labeled at the 10-somite stage by photoconversion of the kaede reporter protein. Lineage analysis was carried out during pharyngeal development in wild-type animals, after miR140 injection, and after estradiol treatment. At the 10-somite stage, cranial neural crest cells anterior of the eye contributed to the median ethmoid plate, whereas cells medial to the eye formed the lateral ethmoid plate and trabeculae and a posterior population formed the mandible. miR-140 overexpression and estradiol inhibition of Hedgehog signaling resulted in cleft development, with failed migration of the anterior cell population to form the median ethmoid plate. The sox10:kaede transgenic line provides a useful tool for neural crest lineage analysis. These studies illustrate the advantages of the zebrafish model for application in morphogenetic studies of vertebrate craniofacial development.

Synergistic roles of Wnt modulators R-spondin2 and R-spondin3 in craniofacial morphogenesis and dental development.

Wnt signaling plays a critical role in craniofacial patterning, as well as tooth and bone development. Rspo2 and Rspo3 are key regulators of Wnt signaling. However, their coordinated function and relative requirement in craniofacial development and odontogensis are poorly understood. We showed that in zebrafish rspo2 and rspo3 are both expressed in osteoprogenitors in the embryonic craniofacial skeleton. This is in contrast to mouse development, where Rspo3 is expressed in osteoprogenitors while Rspo2 expression is not observed. In zebrafish, rspo2 and rspo3 are broadly expressed in the pulp, odontoblasts and epithelial crypts. However, in the developing molars of the mouse, Rspo3 is largely expressed in the dental follicle and alveolar mesenchyme while Rspo2 expression is restricted to the tooth germ. While Rspo3 ablation in the mouse is embryonic lethal, zebrafish rspo3-/- mutants are viable with modest decrease in Meckel's cartilage rostral length. However, compound disruption of rspo3 and rspo2 revealed synergistic roles of these genes in cartilage morphogenesis, fin development, and pharyngeal tooth development. Adult rspo3-/- zebrafish mutants exhibit a dysmorphic cranial skeleton and decreased average tooth number. This study highlights the differential functions of Rspo2 and Rspo3 in dentocranial morphogenesis in zebrafish and in mouse.

Impact of low-frequency coding variants on human facial shape.

The contribution of low-frequency variants to the genetic architecture of normal-range facial traits is unknown. We studied the influence of low-frequency coding variants (MAF < 1%) in 8091 genes on multi-dimensional facial shape phenotypes in a European cohort of 2329 healthy individuals. Using three-dimensional images, we partitioned the full face into 31 hierarchically arranged segments to model facial morphology at multiple levels, and generated multi-dimensional phenotypes representing the shape variation within each segment. We used MultiSKAT, a multivariate kernel regression approach to scan the exome for face-associated low-frequency variants in a gene-based manner. After accounting for multiple tests, seven genes (AR, CARS2, FTSJ1, HFE, LTB4R, TELO2, NECTIN1) were significantly associated with shape variation of the cheek, chin, nose and mouth areas. These genes displayed a wide range of phenotypic effects, with some impacting the full face and others affecting localized regions. The missense variant rs142863092 in NECTIN1 had a significant effect on chin morphology and was predicted bioinformatically to have a deleterious effect on protein function. Notably, NECTIN1 is an established craniofacial gene that underlies a human syndrome that includes a mandibular phenotype. We further showed that nectin1a mutations can affect zebrafish craniofacial development, with the size and shape of the mandibular cartilage altered in mutant animals. Findings from this study expanded our understanding of the genetic basis of normal-range facial shape by highlighting the role of low-frequency coding variants in several novel genes.

Visualization of Chondrocyte Intercalation and Directional Proliferation via Zebrabow Clonal Cell Analysis in the Embryonic Meckel's Cartilage.

Development of the vertebrate craniofacial structures requires precise coordination of cell migration, proliferation, adhesion and differentiation. Patterning of the Meckel's cartilage, a first pharyngeal arch derivative, involves the migration of cranial neural crest (CNC) cells and the progressive partitioning, proliferation and organization of differentiated chondrocytes. Several studies have described CNC migration during lower jaw morphogenesis, but the details of how the chondrocytes achieve organization in the growth and extension of Meckel's cartilage remains unclear. The sox10 restricted and chemically induced Cre recombinase-mediated recombination generates permutations of distinct fluorescent proteins (RFP, YFP and CFP), thereby creating a multi-spectral labeling of progenitor cells and their progeny, reflecting distinct clonal populations. Using confocal time-lapse photography, it is possible to observe the chondrocytes behavior during the development of the zebrafish Meckel's cartilage. Multispectral cell labeling enables scientists to demonstrate extension of the Meckel's chondrocytes. During extension phase of the Meckel's cartilage, which prefigures the mandible, chondrocytes intercalate to effect extension as they stack in an organized single-cell layered row. Failure of this organized intercalating process to mediate cell extension provides the cellular mechanistic explanation for hypoplastic mandible that we observe in mandibular malformations.

Functional analysis of SPECC1L in craniofacial development and oblique facial cleft pathogenesis.

BACKGROUND: Oblique facial clefts, also known as Tessier clefts, are severe orofacial clefts, the genetic basis of which is poorly understood. Human genetics studies revealed that disruption in SPECC1L resulted in oblique facial clefts, demonstrating that oblique facial cleft malformation has a genetic basis. An important step toward innovation in treatment of oblique facial clefts would be improved understanding of its genetic pathogenesis. The authors exploit the zebrafish model to elucidate the function of SPECC1L by studying its homolog, specc1lb. METHODS: Gene and protein expression analysis was carried out by reverse-transcriptase polymerase chain reaction and immunohistochemistry staining. Morpholino knockdown, mRNA rescue, lineage tracing and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assays were performed for functional analysis. RESULTS: Expression of specc1lb was detected in epithelia juxtaposed to chondrocytes. Knockdown of specc1lb resulted in bilateral clefts between median and lateral elements of the ethmoid plate, structures analogous to the frontonasal process and the paired maxillary processes. Lineage tracing analysis revealed that cranial neural crest cells contributing to the frontonasal prominence failed to integrate with the maxillary prominence populations. Cells contributing to lower jaw structures were able to migrate to their destined pharyngeal segment but failed to converge to form mandibular elements. CONCLUSIONS: These results demonstrate that specc1lb is required for integration of frontonasal and maxillary elements and convergence of mandibular prominences. The authors confirm the role of SPECC1L in orofacial cleft pathogenesis in the first animal model of Tessier cleft, providing morphogenetic insight into the mechanisms of normal craniofacial development and oblique facial cleft pathogenesis.

Visualization of craniofacial development in the sox10: kaede transgenic zebrafish line using time-lapse confocal microscopy.

Vertebrate palatogenesis is a highly choreographed and complex developmental process, which involves migration of cranial neural crest (CNC) cells, convergence and extension of facial prominences, and maturation of the craniofacial skeleton. To study the contribution of the cranial neural crest to specific regions of the zebrafish palate a sox10: kaede transgenic zebrafish line was generated. Sox10 provides lineage restriction of the kaede reporter protein to the neural crest, thereby making the cell labeling a more precise process than traditional dye or reporter mRNA injection. Kaede is a photo-convertible protein that turns from green to red after photo activation and makes it possible to follow cells precisely. The sox10: kaede transgenic line was used to perform lineage analysis to delineate CNC cell populations that give rise to maxillary versus mandibular elements and illustrate homology of facial prominences to amniotes. This protocol describes the steps to generate a live time-lapse video of a sox10: kaede zebrafish embryo. Development of the ethmoid plate will serve as a practical example. This protocol can be applied to making a time-lapse confocal recording of any kaede or similar photoconvertible reporter protein in transgenic zebrafish. Furthermore, it can be used to capture not only normal, but also abnormal development of craniofacial structures in the zebrafish mutants.

High-throughput assay for bacterial adhesion on acellular dermal matrices and synthetic surgical materials.

BACKGROUND: There has been increasing use of synthetic and acellular dermal matrix materials in surgery, ranging from breast reconstruction to hernia repairs. There is a paucity of data on how acellular dermal matrix compares with other surgical materials as a substrate for bacterial adhesion, the first step in formation biofilm, which occurs in prosthetic wound infections. The authors have designed a high-throughput assay to evaluate Staphylococcus aureus adherence on various synthetic and biologically derived materials. METHODS: Clinical isolates of S. aureus (strains SC-1 and UAMS-1) were cultured with different materials, and bacterial adherence was measured using a resazurin cell vitality assay. Four materials that are commonly used in surgery were evaluated: Prolene mesh, Vicryl mesh, and two different acellular dermal matrix preparations (AlloDerm and FlexHD). The authors were able to develop a high-throughput and reliable assay for quantifying bacterial adhesion on synthetic and biologically derived materials. RESULTS: The resazurin vitality assay can be reliably used to quantify bacterial adherence to acellular dermal matrix material and synthetic material. S. aureus strains SC-1 and UAMS-1 both adhered better to acellular dermal matrix materials (AlloDerm versus FlexHD) than to the synthetic material Prolene. S. aureus also adhered better to Vicryl than to Prolene. Strain UAMS-1 adhered better to Vicryl and acellular dermal matrix materials than did strain SC-1. CONCLUSIONS: The results show that S. aureus adheres more readily to acellular dermal matrix material than to synthetic material. The resazurin assay provides a standard method for evaluating surgical materials with regard to bacterial adherence and potential propensity for biofilm development.

Zebrafish wnt9a is expressed in pharyngeal ectoderm and is required for palate and lower jaw development.

Wnt activity is critical in craniofacial morphogenesis. Dysregulation of Wnt/ß-catenin signaling results in significant alterations in the facial form, and has been implicated in cleft palate phenotypes in mouse and man. In zebrafish, we show that wnt9a is expressed in the pharyngeal arch, oropharyngeal epithelium that circumscribes the ethmoid plate, and ectodermal cells superficial to the lower jaw structures. Alcian blue staining of morpholino-mediated knockdown of wnt9a results in loss of the ethmoid plate, absence of lateral and posterior parachordals, and significant abrogation of the lower jaw structures. Analysis of cranial neural crest cells in the sox10:eGFP transgenic demonstrates that the wnt9a is required early during pharyngeal development, and confirms that the absence of Alcian blue staining is due to absence of neural crest derived chondrocytes. Molecular analysis of genes regulating cranial neural crest migration and chondrogenic differentiation suggest that wnt9a is dispensable for early cranial neural crest migration, but is required for chondrogenic development of major craniofacial structures. Taken together, these data corroborate the central role for Wnt signaling in vertebrate craniofacial development, and reveal that wnt9a provides the signal from the pharyngeal epithelium to support craniofacial chondrogenic morphogenesis in zebrafish.