Midline Facial Cleft Research Articles

PDGFRα signaling regulates Srsf3 transcript binding to affect PI3K signaling and endosomal trafficking.

Signaling through the platelet-derived growth factor receptor alpha (PDGFRα) plays a critical role in craniofacial development, as mutations in PDGFRA are associated with cleft lip/palate in humans and Pdgfra mutant mouse models display varying degrees of facial clefting. Phosphatidylinositol 3-kinase (PI3K)/Akt is the primary effector of PDGFRα signaling during skeletal development in the mouse. We previously demonstrated that Akt phosphorylates the RNA-binding protein serine/arginine-rich splicing factor 3 (Srsf3) downstream of PI3K-mediated PDGFRα signaling in mouse embryonic palatal mesenchyme (MEPM) cells, leading to its nuclear translocation. We further showed that ablation of Srsf3 in the murine neural crest lineage results in severe midline facial clefting, due to defects in proliferation and survival of cranial neural crest cells, and widespread alternative RNA splicing (AS) changes. Here, we sought to determine the molecular mechanisms by which Srsf3 activity is regulated downstream of PDGFRα signaling to control AS of transcripts necessary for craniofacial development. We demonstrated via enhanced UV-crosslinking and immunoprecipitation (eCLIP) of MEPM cells that PDGF-AA stimulation leads to preferential binding of Srsf3 to exons and loss of binding to canonical Srsf3 CA-rich motifs. Through the analysis of complementary RNA-seq data, we showed that Srsf3 activity results in the preferential inclusion of exons with increased GC content and lower intron to exon length ratio. Moreover, we found that the subset of transcripts that are bound by Srsf3 and undergo AS upon PDGFRα signaling commonly encode regulators of PI3K signaling and early endosomal trafficking. Functional validation studies further confirmed that Srsf3 activity downstream of PDGFRα signaling leads to retention of the receptor in early endosomes and increases in downstream PI3K-mediated Akt signaling. Taken together, our findings reveal that growth factor-mediated phosphorylation of an RNA-binding protein underlies gene expression regulation necessary for mammalian craniofacial development.

Single-cell transcriptomic signatures and gene regulatory networks modulated by Wls in mammalian midline facial formation and clefts.

Formation of highly unique and complex facial structures is controlled by genetic programs that are responsible for the precise coordination of three-dimensional tissue morphogenesis. However, the underlying mechanisms governing these processes remain poorly understood. We combined mouse genetic and genomic approaches to define the mechanisms underlying normal and defective midfacial morphogenesis. Conditional inactivation of the Wnt secretion protein Wls in Pax3-expressing lineage cells disrupted frontonasal primordial patterning, cell survival and directional outgrowth, resulting in altered facial structures, including midfacial hypoplasia and midline facial clefts. Single-cell RNA sequencing revealed unique transcriptomic atlases of mesenchymal subpopulations in the midfacial primordia, which are disrupted in the conditional Wls mutants. Differentially expressed genes and cis-regulatory sequence analyses uncovered that Wls modulates and integrates a core gene regulatory network, consisting of key midfacial regulatory transcription factors (including Msx1, Pax3 and Pax7) and their downstream targets (including Wnt, Shh, Tgfβ and retinoic acid signaling components), in a mesenchymal subpopulation of the medial nasal prominences that is responsible for midline facial formation and fusion. These results reveal fundamental mechanisms underlying mammalian midfacial morphogenesis and related defects at single-cell resolution.

A Rare Patient With Midline Facial Cleft.

Midline facial cleft, namely Tessier number 0 cleft, is the most common kind of craniofacial cleft, which is described as a median facial dysrhaphia, involving the midline structures of the face below the orbit. The authors report a patient with midline facial cleft, having palatal cleft, absent premaxilla and nasal septum, and other associated features. Clinical features, surgical treatment, and possible etiology have been elaborated in this clinical report.

Frontonasal Dysplasia in Yangon, Myanmar

Frontonasal dysplasia (FND) is an uncommon congenital anomaly affecting the eyes, nose and forehead. In this case report, a baby of a 22-year-old mother was diagnosed with a midline facial cleft, bifid nose and hypertelorism during an ultrasound scan at 29th week of gestation. Besides a history of miscarriage on first pregnancy, no other abnormalities findings were found in laboratory or radiological examination of the newborn. Counselling about abnormality and psychological support were given by both obstetrician and neonatologist during the antenatal period. The patient delivered vaginally at 36th week with spontaneous labour and no complication was observed. Further interventions including corrective treatment have been planned as they often interfere with important functions such as breathing and feeding. Thus, the paediatric surgical team decided to do the operation when the baby reaches one year old as then tissues have been developed to 90% of their eventual form to give optimal treatment results. Further life expectancy depends on the severity of the malformation and whether or not surgical intervention can improve the associated health problems. This case report raises the importance of awareness on the nutritional value of pregnant mothers especially carotene and folic acid intake which may be associated with the organ maldevelopment. Overall, this report outlined the management of this rare condition experienced by the patient, particularly in a resource-limited setting like Yangon in Myanmar and also reviewed the literature about the presentation and classification of this condition.

Generation and characterization of Six2 conditional mice

Heterozygous deletion of Six2, which encodes a member of sine oculis homeobox family transcription factors, has recently been associated with the frontonasal dysplasia syndrome FND4. Previous studies showed that Six2 is expressed in multiple tissues during craniofacial development in mice, including embryonic head mesoderm, postmigratory frontonasal neural crest cells, and epithelial and mesenchymal cells of the developing palate and nasal structures. Whereas Six2 -/- mice exhibited cranial base defects but did not recapitulate frontonasal phenotypes of FND4 patients, Six1 -/- Six2 -/- double mutant mice showed severe craniofacial defects including midline facial clefting. The complex phenotypes of FND4 patients and of Six1 -/- Six2 -/- mutant mice indicate that Six2 plays crucial roles in distinct cell types at multiple stages of craniofacial morphogenesis. Here we report generation of mice carrying insertions of a pair of loxP sites flanking exon-1 of the Six2 gene (Six2 f allele) using CRISPR/Cas9-mediated genome editing. We show that the Six2 f allele functions normally and is effectively inactivated by Cre-mediated recombination in vivo. Furthermore, we show that Six2 f/f ;Wnt1-Cre mice recapitulated cranial base defects but not neonatal lethality of Six2 -/- mice. These results indicate that Six2 f/f mice enable systematic investigation of cell type- and stage-specific Six2 function in development and disease.

Crucial and Overlapping Roles of Six1 and Six2 in Craniofacial Development

SIX1 and SIX2 encode closely related transcription factors of which disruptions have been associated with distinct craniofacial syndromes, with mutations in SIX1 associated with branchiootic syndrome 3 (BOS3) and heterozygous deletions of SIX2 associated with frontonasal dysplasia defects. Whereas mice deficient in Six1 recapitulated most of the developmental defects associated with BOS3, mice lacking Six2 function had no obvious frontonasal defects. We show that Six1 and Six2 exhibit partly overlapping patterns of expression in the developing mouse embryonic frontonasal, maxillary, and mandibular processes. We found that Six1 –/– Six2 –/– double-mutant mice were born with severe craniofacial deformity not seen in the Six1 –/– or Six2 –/– single mutants, including skull bone agenesis, midline facial cleft, and syngnathia. Moreover, whereas Six1 –/– mice exhibited partial transformation of maxillary zygomatic bone into a mandibular condyle-like structure, Six1 –/– Six2 +/– mice exhibit significantly increased penetrance of the maxillary malformation. In addition to ectopic Dlx5 expression at the maxillary-mandibular junction as recently reported in E10.5 Six1 –/– embryos, the E10.5 Six1 –/– Six2 +/– embryos showed ectopic expression of Bmp4, Msx1, and Msx2 messenger RNAs in the maxillary-mandibular junction. Genetically inactivating 1 allele of either Ednra or Bmp4 significantly reduced the penetrance of maxillary malformation in both Six1 –/– and Six1 –/– Six2 +/– embryos, indicating that Six1 and Six2 regulate both endothelin and bone morphogenetic protein-4 signaling pathways to pattern the facial structures. Furthermore, we show that neural crest–specific inactivation of Six1 in Six2 –/– embryos resulted in midline facial cleft and frontal bone agenesis. We show that Six1 –/– Six2 –/– embryos exhibit significantly reduced expression of key frontonasal development genes Alx1 and Alx3 as well as increased apoptosis in the developing frontonasal mesenchyme. Together, these results indicate that Six1 and Six2 function partly redundantly to control multiple craniofacial developmental processes and play a crucial neural crest cell–autonomous role in frontonasal morphogenesis.

Diagnostic criteria in Pai syndrome: results of a case series and a literature review

Pai syndrome was originally described as the association of a midline cleft lip, midline facial polyps, and lipoma of the central nervous system. However, only a few patients present with the full triad, and most exhibit a wide spectrum of phenotypic variability. The aim of this study was to phenotypically delineate Pai syndrome and to propose new criteria to facilitate a clinical diagnosis in the future. The study cohort consisted of seven case patients and an additional 60 cases diagnosed with Pai syndrome identified in a literature review. Only 23 of 67 patients presented the full triad as historically described by Pai et al. (1987). A congenital facial midline skin mass was always encountered, particularly affecting the nasal structures (60/67). A midline facial cleft was reported in 45 of 67 patients and a pericallosal lipoma in 42 of 67 patients. The proposed definition of Pai syndrome is the association of (1) a congenital nasal and/or mediofrontal skin mass and/or a mid-anterior alveolar process polyp as a mandatory criterion, and at least one of the following criteria: (2) midline cleft lip and/or midline alveolar cleft, and/or (3) a pericallosal lipoma or interhemispheric lipoma in the case of corpus callosum dysgenesis.

Computer-Assisted Surgery in Facial Bipartition Surgery

Frontonasal dysplasia or median cleft syndrome is a rare condition often associated with transverse maxillary deficiency for which facial bipartition is the proper surgical treatment. This technical note describes the use and efficacy of 3-dimensional virtual surgical planning and patient-specific cutting guides in facial bipartition. An 11-year-old boy presented with frontonasal dysplasia and a midline facial cleft. Computed tomographic (CT) scan visualized an intercanthal distance of 40mm and a maxillary width at the secondmolar level of 46.2mm. The osteotomies, amount of bone removal, and movement of the osteotomized bone were planned virtually based on CT findings: the intended postoperative intercanthal distance and maxillary width were 25.5 and 49.6mm, respectively. Customized cutting guides and titanium miniplates were manufactured. Postoperative CT scan showed an intercanthal distance of 25.5mm and a maxillary width of 49.7mm. The intercanthal distances and maxillary widths were similar between the simulation and postoperative CT images, confirming the accuracy and utility of computer-assisted surgery in facial bipartition.

Mllt10 knockout mouse model reveals critical role of Af10-dependent H3K79 methylation in midfacial development

Epigenetic regulation is required to ensure the precise spatial and temporal pattern of gene expression that is necessary for embryonic development. Although the roles of some epigenetic modifications in embryonic development have been investigated in depth, the role of methylation at lysine 79 (H3K79me) is poorly understood. Dot1L, a unique methyltransferase for H3K79, forms complexes with distinct sets of co-factors. To further understand the role of H3K79me in embryogenesis, we generated a mouse knockout of Mllt10, the gene encoding Af10, one Dot1L complex co-factor. We find homozygous Mllt10 knockout mutants (Mllt10-KO) exhibit midline facial cleft. The midfacial defects of Mllt10-KO embryos correspond to hyperterolism and are associated with reduced proliferation of mesenchyme in developing nasal processes and adjacent tissue. We demonstrate that H3K79me level is significantly decreased in nasal processes of Mllt10-KO embryos. Importantly, we find that expression of AP2α, a gene critical for midfacial development, is directly regulated by Af10-dependent H3K79me, and expression AP2α is reduced specifically in nasal processes of Mllt10-KO embryos. Suppression of H3K79me completely mimicked the Mllt10-KO phenotype. Together these data are the first to demonstrate that Af10-dependent H3K79me is essential for development of nasal processes and adjacent tissues, and consequent midfacial formation.

A case report on midline facial cleft associated with ambiguous genitalia and umbilical defect

A case report on midline facial cleft associated with ambiguous genitalia and umbilical defect

Early two-stage repair of clefts in holoprosencephaly

Holoprosencephaly (HPE) presents with a spectrum of severity, but in its totality is the most common malformation of the embryonic forebrain occurring 1 in 10,000 to 1 in 20,000 live births. Due to the poor prognosis, treatment of mid-face clefts in HPE patients have classically been addressed in a delayed fashion after 1-year of age. Improvements in the ability to manage medical complications associated with HPE along with an increased understanding and lower mortality rates in less severe forms have challenged these previous practiced routines. Accompanied by advances in understanding of HPE and identification of genes responsible for sporadic forms, we are able to better guide timing of surgical intervention. We present a patient with lobar HPE and a type IV facial deformity treated with early repair of the median facial cleft. We believe this treatment strategy was safe, given her relatively good prognosis. We propose that patients with HPE displaying less severe neural non-cleavage may be good candidates for earlier two-stage intervention. SummaryThe historically poor prognosis of patients with holoprosencephaly (HPE) has led to midline facial clefts have being addressed in a delayed fashion after 1-year of age. Improvements in the ability to manage medical complications associated with HPE and lower mortality rates in less severe forms have challenged these previous practiced routines. Additionally, the identification of genes responsible for sporadic forms of HPE can better guide timing of surgical intervention and improve developmental outcomes. We present a patient with lobar HPE and a type IV facial deformity treated with an early two-stage repair of the median facial cleft. We propose patients with HPE displaying less severe neural non-cleavage may be good candidates for earlier intervention.

Management of Midline Facial Clefts.

Median or midline facial clefts are rare anomalies of developmental origin, etiology of whose occurrence is still unknown precisely. The most basic presentation of midline facial clefts is in the form of a Median cleft lip which is defined as any congenital vertical cleft through the centre of the upper lip. First described by Bechard in 1823, it is the most common amongst all atypical clefts reported. The incidence is about 1:10,00,000 births. This may occur as a sporadic event or as a part of an inherited sequence of anomalies. It arises embryologically from incomplete fusion of the medial nasal prominences. The authors present a series of eight cases with varying degrees of midline facial clefts. This review article aims to give a broad idea on the various classifications used for further understanding of midline facial clefts and a brief idea about the various surgical management techniques used in the repair of these facial clefts.

Tessier number 30 cleft: report of an antenatally diagnosed case

Abstract Tessier no. 30 cleft, also known as median mandibular cleft or lower midline facial cleft, is extremely rare. Less than 100 cases are reported in the literature, which show great variation in severity and associated abnormalities. We herein report a median mandibular cleft extending into the neck. Its importance comes from the fact that it is one of the two cases diagnosed antenatally and it is the first one diagnosed as early as 17 weeks of gestation. Early diagnosis allowed the patient to deliver in a more specialized clinic that was able to deal with immediate postnatal complications. The family was psychologically prepared for the delivery of a baby with a major anomaly.

Morphological defects in a novel Rdh10 mutant that has reduced retinoic acid biosynthesis and signaling

Retinoic acid (RA) signaling is necessary for proper patterning and morphogenesis during embryonic development. Tissue-specific RA signaling requires precise spatial and temporal synthesis of RA from retinal by retinaldehyde dehydrogenases (Raldh) and the conversion of retinol to retinal by retinol dehydrogenases (Rdh) of the short-chain dehydrogenase/reducatase gene family (SDR). The SDR, retinol dehydrogenase 10 (RDH10), is a major contributor to retinal biosynthesis during mid-gestation. We have identified a missense mutation in the Rdh10 gene (Rdh10(m366Asp) ) using an N-ethyl-N-nitrosourea-induced forward genetic screen that result in reduced RA levels and signaling during embryonic development. Rdh10(m366Asp) mutant embryos have unique phenotypes, such as edema, a massive midline facial cleft, and neurogenesis defects in the forebrain, that will allow the identification of novel RA functions.

Encefalocele basal esfenoetmoidal associada a fissura labiopalatina mediana: relato de caso

Associação de encefalocele basal esfenoetmoidal com fissura labiopalatina é extremamente rara. Relatamos um caso de uma criança de nove anos de idade apresentando uma fissura facial mediana com meningocele, que era evidente através da falha do palato como uma massa mediana intranasal pulsátil. Uma análise dos aspectos clínicos e radiológicos deste caso de disrafia craniana foi realizada.

Cecr2 mutations causing exencephaly trigger misregulation of mesenchymal/ectodermal transcription factors

Over 200 mouse genes are associated with neural tube defects (NTDs), including Cecr2, the bromodomain-containing subunit of the CERF chromatin remodeling complex. Gene-trap mutation Cecr2(Gt45Bic) results in 74% exencephaly (equivalent of human anencephaly) on the BALB/c strain. Gene expression altered during cranial neural tube closure by the Cecr2 mutation was identified through microarray analysis of 11-14 somites stage Cecr2(Gt45Bic)embryos. Analysis of Affymetrix Mouse 430 2.0 chips detected 60 transcripts up-regulated and 54 transcripts down-regulated in the Cecr2(Gt45Bic) embryos (fold > 1.5, p < 0.05). The Cecr2 transcript was reduced only approximately 7- to 14-fold from normal levels, suggesting the Cecr2(Gt45Bic) is a hypomorphic mutation. We therefore generated a novel Cecr2 null allele (Cecr2 (tm1.1Hemc)). Resulting mutants displayed a stronger penetrance of exencephaly than Cecr2(Gt45Bic) in both BALB/c and FVB/N strains, in addition to midline facial clefts and forebrain encephalocele in the FVB/N strain. The Cecr2 transcript is reduced 260-fold in the Cecr2(tm1.1Hemc) line. Subsequent qRT-PCR using Cecr2 (tm1.1Hemc) mutant heads confirmed downregulation of transcription factors Alx1/Cart1, Dlx5, Eya1, and Six1. As both Alx1/Cart1 and Dlx5 mouse mutations result in exencephaly, we hypothesize that changes in expression of these mesenchymal/ectodermal transcription factors may contribute to NTDs associated with Cecr2.

Zebrafish con/disp1 reveals multiple spatiotemporal requirements for Hedgehog-signaling in craniofacial development

BackgroundThe vertebrate head skeleton is derived largely from cranial neural crest cells (CNCC). Genetic studies in zebrafish and mice have established that the Hedgehog (Hh)-signaling pathway plays a critical role in craniofacial development, partly due to the pathway's role in CNCC development. Disruption of the Hh-signaling pathway in humans can lead to the spectral disorder of Holoprosencephaly (HPE), which is often characterized by a variety of craniofacial defects including midline facial clefting and cyclopia [1,2]. Previous work has uncovered a role for Hh-signaling in zebrafish dorsal neurocranium patterning and chondrogenesis, however Hh-signaling mutants have not been described with respect to the ventral pharyngeal arch (PA) skeleton. Lipid-modified Hh-ligands require the transmembrane-spanning receptor Dispatched 1 (Disp1) for proper secretion from Hh-synthesizing cells to the extracellular field where they act on target cells. Here we study chameleon mutants, lacking a functional disp1(con/disp1).Resultscon/disp1 mutants display reduced and dysmorphic mandibular and hyoid arch cartilages and lack all ceratobranchial cartilage elements. CNCC specification and migration into the PA primorida occurs normally in con/disp1 mutants, however disp1 is necessary for post-migratory CNCC patterning and differentiation. We show that disp1 is required for post-migratory CNCC to become properly patterned within the first arch, while the gene is dispensable for CNCC condensation and patterning in more posterior arches. Upon residing in well-formed pharyngeal epithelium, neural crest condensations in the posterior PA fail to maintain expression of two transcription factors essential for chondrogenesis, sox9a and dlx2a, yet continue to robustly express other neural crest markers. Histology reveals that posterior arch residing-CNCC differentiate into fibrous-connective tissue, rather than becoming chondrocytes. Treatments with Cyclopamine, to inhibit Hh-signaling at different developmental stages, show that Hh-signaling is required during gastrulation for normal patterning of CNCC in the first PA, and then during the late pharyngula stage, to promote CNCC chondrogenesis within the posterior arches. Further, loss of disp1 disrupted normal expression of bapx1 and gdf5, markers of jaw joint patterning, thus resulting in jaw joint defects in con/disp1 mutant animals.ConclusionThis study reveals novel requirements for Hh-signaling in the zebrafish PA skeleton and highlights the functional diversity and differential sensitivity of craniofacial tissues to Hh-signaling throughout the face, a finding that may help to explain the spectrum of human facial phenotypes characteristic of HPE.

Holoprosenzephalie: Kriterien und Konsequenzen der pränatalen Diagnostik

Two cases of prenatal diagnosis of holoprosencephaly are described. The characteristic sonographic findings in the second trimester were: microcephaly, absence of the midline echo, hypotelorism and typically flattened profile without sufficient configuration of the nose. Both foetuses had midline facial clefts, one of which was diagnosed prenatally. One case demonstrated a dorsal intracranial cyst. Analysis of the karyotype after foetal blood sampling and amniocentesis revealed translocation trisomy 13 in one case. The mother of this foetus had a balanced translocation 13/14. This foetus also had many extracranial abnormalities in contrast to the other foetus, which had a normal karyotype. Additionally we report of the prenatal diagnosis of a third case with cyclopia and trisomy 13. The findings of the autopsy of the foetuses are described and the criteria for prenatal diagnosis are compared to those found in the literature.

Morning-glory-Papille und frontonasale Dysplasie

Morning glory disc anomaly (MGDA) is a rare congenital malformation of the optic disc, which can be associated with midline craniofacial abnormalities, such as basal encephalocele. A female neonate presented with MGDA in the right eye, pendular nystagmus, hypertelorism, a flattened nasal root and cleft lip and palate. MRI revealed a basal encephalocele, agenesis of the corpus callosum and ventricular enlargement. MGDA combined with midline facial clefting should always lead to the suspicion of a basal encephalocele.

Caution in Treating Transsphenoidal Encephalocele with Concomitant Moyamoya Disease

A basal encephalocele is a rare congenital malformation involving a cranial bone defect and cystic-like herniation through the defect. Moyamoya is a rare cerebrovascular disease of unclear etiology involving occlusion of the distal internal carotids and formation of collateral vascular networks. Both diseases have been correlated with optic disc anomalies, hypopituitarism, and midfacial defects. We present a case of a 2-year-old boy with a midline facial cleft who underwent surgical correction of a basal encephalocele. His moyamoya disease may have contributed to a vascular complication. There is growing evidence indicating an overlap in disease profiles for these two rare diseases. In addition, molecular evidence indicates elevated levels of fibroblast growth factor and transforming growth factor in both diseases, suggesting common molecular pathways.