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Objective: Van der Woude syndrome is characterized by the concurrence of cleft lip and palate with lower lip fistulas. During fistula resection, care must be taken to maintain the function of the orbicularis oris and restore the normal shape of the lips. Several reports have documented various resection methods; however, the most appropriate surgical resection is controversial. In this report, lower lip fistulas were resected using an inverted‐T surgical design. Methods: Of the six patients with Van der Woude syndrome who underwent resection of the lower lip fistula in our department between January 2007 and December 2015, three patients who underwent inverted‐T lip reduction were included. The postoperative position‐dependent morphology of the fistulas was examined. Results: Five years postoperatively, no complications such as postoperative infections, mucous retention cyst formation, a dysmorphic appearance of the lip, or fistula recurrence were observed. Moreover, a stable wound morphology was evident. Conclusions: The inverted‐T lip reduction seems to be promising technique for the excision of lower lip fistulas in patients with Van der Woude syndrome, yielding good results. [ABSTRACT FROM AUTHOR]

Several mutations in the IRF6 gene have been identified as a causative link to VWS. In this investigation, whole-exome sequencing (WES) and Sanger sequencing of a three-generation pedigree with an autosomal-dominant inheritance pattern affected by VWS identified a unique stop-gain mutation-c.748C>T:p.R250X-in the IRF6 gene that co-segregated exclusively with the disease phenotype. Immunofluorescence analysis revealed that the IRF6-p.R250X mutation predominantly shifted its localization from the nucleus to the cytoplasm. WES and protein interaction analyses were conducted to understand this mutation's role in the pathogenesis of VWS. Using LC-MS/MS, we found that this mutation led to a reduction in the binding of IRF6 to histone modification-associated proteins (NAA10, SNRPN, NAP1L1). Furthermore, RNA-seq results show that the mutation resulted in a downregulation of TGFβ2-AS1 expression. The findings highlight the mutation's influence on TGFβ2-AS1 and its subsequent effects on the phosphorylation of SMAD2/3, which are critical in maxillofacial development, particularly the palate. These insights contribute to a deeper understanding of VWS's molecular underpinnings and might inform future therapeutic strategies. [ABSTRACT FROM AUTHOR]

The fusion of digits or toes, syndactyly, can be part of complex syndromes, including van der Woude syndrome. A subset of van der Woude cases is caused by dominant-negative mutations in the epithelial transcription factor Grainyhead like-3 (GRHL3), and Grhl3-/-mice have soft-tissue syndactyly. Although impaired interdigital cell death of mesenchymal cells causes syndactyly in multiple genetic mutants, Grhl3-/- embryos had normal interdigital cell death, suggesting alternative mechanisms for syndactyly. We found that in digit separation, the overlying epidermis forms a migrating interdigital epithelial tongue (IET) when the epithelium invaginates to separate the digits. Normally, the non-adhesive surface periderm allows the IET to bifurcate as the digits separate. In contrast, in Grhl3-/- embryos, the IET moves normally between the digits but fails to bifurcate because of abnormal adhesion of the periderm. Our study identifies epidermal developmental processes required for digit separation.

Background: To date, there are over 320 variants identified in the IRF6 gene that cause Van der Woude syndrome or popliteal pterygium syndrome. We sequenced this gene in a South African orofacial cleft cohort to identify the causal IRF6 variants in our population. Method: Saliva samples from 100 patients with syndromic and non‐syndromic CL ± P were collected. Patients were recruited from the cleft clinics at two public, tertiary hospitals in Durban, South Africa (SA), namely Inkosi Albert Luthuli Central Hospital (IALCH) and KwaZulu‐Natal Children's Hospital (KZNCH). We prospectively sequenced the exons of IRF6 in 100 orofacial cleft cases, and where possible, we also sequenced the parents of the individuals to determine the segregation pattern. Results: Two variants were identified; one novel (p.Cys114Tyr) and one known (p.Arg84His) missense variant in IRF6 gene were identified. The patient with the p.Cys114Tyr variant was non‐syndromic with no clinical VWS phenotype expected of individuals with IRF6 coding variants, and the patient with the p.Arg84His had phenotypic features of popliteal pterygium syndrome. The p.Arg84His variant segregated in the family, with the father also being affected. Conclusions: This study provides evidence that IRF6 variants are found in the South African population. Genetic counselling is essential for affected families, particularly in the absence of a known clinical phenotype since it helps with the plans for future pregnancies. [ABSTRACT FROM AUTHOR]

Although the aetiology of non-syndromic orofacial clefts (nsOFCs) is usually multifactorial, syndromic OFCs (syOFCs) are often caused by single mutations in known genes. Some syndromes, e.g., Van der Woude syndrome (VWS1; VWS2) and X-linked cleft palate with or without ankyloglossia (CPX), show only minor clinical signs in addition to OFC and are sometimes difficult to differentiate from nsOFCs. We recruited 34 Slovenian multi-case families with apparent nsOFCs (isolated OFCs or OFCs with minor additional facial signs). First, we examined IRF6, GRHL3, and TBX22 by Sanger or whole exome sequencing to identify VWS and CPX families. Next, we examined 72 additional nsOFC genes in the remaining families. Variant validation and co-segregation analysis were performed for each identified variant using Sanger sequencing, real-time quantitative PCR and microarray-based comparative genomic hybridization. We identified six disease-causing variants (three novel) in IRF6, GRHL3, and TBX22 in 21% of families with apparent nsOFCs, suggesting that our sequencing approach is useful for distinguishing syOFCs from nsOFCs. The novel variants, a frameshift variant in exon 7 of IRF6, a splice-altering variant in GRHL3, and a deletion of the coding exons of TBX22, indicate VWS1, VWS2, and CPX, respectively. We also identified five rare variants in nsOFC genes in families without VWS or CPX, but they could not be conclusively linked to nsOFC. [ABSTRACT FROM AUTHOR]

IntroductionVan der Woude syndrome (VWS) is an autosomal dominant disorder responsible for 2% of all syndromic orofacial clefts (OFCs), with IRF6 being the primary causal gene (70%). Cases may present with lip pits and either cleft lip, cleft lip with cleft palate, or cleft palate, with marked phenotypic discordance even among individuals carrying the same mutation. This suggests that genetic or epigenetic modifiers may play additional roles in the syndrome's etiology and variability in expression. We report the first DNA methylation profiling of two pairs of monozygotic twins with VWS. Our goal is to explore epigenetic contributions to VWS etiology and variable phenotypic expressivity by comparing DNAm profiles in both twin pairs. While the mutations that cause VWS in these twins are known, the additional mechanism behind their phenotypic risk and variability in expression remains unclear.MethodsWe generated whole genome DNAm data for both twin pairs. Differentially methylated positions (DMPs) were selected based on: (1) a coefficient of variation in DNAm levels in unaffected individuals 5% (Δβ > |0.05|). We then divided the DMPs into two subgroups for each twin pair for further analysis: (1) higher methylation levels in twin A (Twin A > Twin B); and (2) higher methylation levels in twin B (Twin B >Twin A).Results and DiscussionGene ontology analysis revealed a list of enriched genes that showed significant differential DNAm, including clef-associated genes. Among the cleft-associated genes, TP63 was the most significant hit (p = 7.82E-12). Both twin pairs presented differential DNAm levels in CpG sites in/near TP63 (Twin 1A > Twin 1B and Twin 2A < Twin 2B). The genes TP63 and IRF6 function in a biological regulatory loop to coordinate epithelial proliferation and differentiation in a process that is critical for palatal fusion. The effects of the causal mutations in IRF6 can be further impacted by epigenetic dysregulation of IRF6 itself or genes in its pathway. Our data show evidence that changes in DNAm are a plausible mechanism that can lead to markedly distinct phenotypes, even among individuals carrying the same mutation.

Van der Woude syndrome is a rare congenital condition with autosomal dominant traits. This autosomal dominant syndrome had been reported to have a penetrance of 80% with variable expression.[1] This genetic disorder is characterized by the combination of lip pits, cleft lip with or without cleft palate, and cleft palate only. Even within the families, there is a wide variability of affected gene expressions. It is very important to establish the correct diagnosis so that genetic counseling can be recommended in such cases. Here, we report cases of Van der Woude syndrome in the same family having the same genetic inheritance with variable expression.

In Van der Woude syndrome (VWS), a rare congenital disease, lower lip pits (LLPs) can cause an aesthetically significant deformity. Surgical treatment of LLPs is necessary if they cause recurrent inflammation or aesthetic problems. Intraoperatively, surgeons should keep in mind the possibility of deep extension of the sinus tract and the relative deficiency of the midline in VWS, which increases the risk of lip disfigurement. Herein, we emphasize the importance of using a tissue-preserving technique to improve aesthetic results in VWS patients with a sinus tract.

Rare mutations in IRF6 and GRHL3 cause Van der Woude syndrome, an autosomal dominant orofacial clefting disorder. Common variants in IRF6 and GRHL3 also contribute risk for isolated orofacial clefting. Similarly, variants within genes that encode receptor tyrosine kinase (RTK) signaling components, including members of the FGF pathway, EPHA3 and SPRY2, also contribute risk for isolated orofacial clefting. In the mouse, loss of Irf6 or perturbation of Fgf signaling leads to abnormal oral epithelial adhesions and cleft palate. Oral adhesions can result from a disruption of periderm formation. Here, we find that IRF6 and SPRY4 signaling interact in periderm function. We crossed Irf6 heterozygous ( Irf6+/-) mice with transgenic mice that express Spry4 in the basal epithelial layer ( TgKRT14::Spry4). While embryos with either of these mutations can have abnormal oral adhesions, using a new quantitative assay, we observed a nonadditive effect of abnormal oral epithelial adhesions in the most severely affected double mutant embryos ( Irf6+/-;TgKRT14::Spry4). At the molecular level, the sites of abnormal oral adhesions maintained periderm-like cells that express keratin 6, but we observed abnormal expression of GRHL3. Together, these data suggest that Irf6 and RTK signaling interact in regulating periderm differentiation and function, as well as provide a rationale to screen for epistatic interactions between variants in IRF6 and RTK signaling pathway genes in human orofacial clefting populations.

Orofacial clefts are common birth defects and Van der Woude syndrome (VWS) is the most common form of orofacial cleft syndrome, accounting for approximately 2% of patients with a cleft.[1],[2] The cardinal features of VWS are lower lip pits associated with cleft lip and/or palate.[2],[3],[4] Lip pits are reported to occur in over 80% of individuals with VWS.[2] Most reported cases of VWS have been linked to chromosome 1q32-q41.[5],[6],[7] The interferon regulatory factor 6 (IRF6) gene, which is located at 1q32-p41 region, has been implicated in several studies.[2],[8] There are over 300 IRF6 variants that have been identified in patients with VWS, with approximately 50% of these being missense variants.[9] This paper describes a 7.5-year-old male patient that is heterozygous for a missense variant in C.101A >C p.(Lys34Thr) which is likely to be pathogenic.[9] This patient has the cardinal features for VWS but also has duodenal atresia. Neither the truncating variant identified in this patient nor other variants associated with VWS have been previously linked to duodenal atresia.

Background: Congenital maxillomandibular syngnathia is a rare craniofacial anomaly leading to difficulties in feeding, breathing and ability to thrive. The fusion may consist of soft tissue union (synechiae) to hard tissue union. Isolated cases of maxillomandibular fusion are extremely rare, it is most often syndromic in etiology. Case presentation: Clinical management of a female newborn with oromaxillofacial abnormities (synechiae, cleft palate, craniofacial dysmorphisms, dental anomaly) and extraoral malformations (skinfold overlying the nails of both halluces, syndactyly, abnormal external genitalia) is presented. The associated malformations addressed to molecular genetic investigations revealing an interferon regulatory factor 6 (IRF6)-related disorder (van der Woude syndrome/popliteal pterygium syndrome). A novel de novo heterozygous mutation in exon 4 of IRF6 gene on chromosome 1q32.2, precisely c.262A > G (p.Asn88Asp), was found. Similarities are discussed with known asparagine missense mutations in the same codon, which may alter IRF6 gene function by reduced DNA-binding ability. A concomitant maternal Xp11.22 duplication involving two microRNA genes could contribute to possible epigenetic effects. Conclusions: Our reported case carrying a novel mutation can contribute to expand understandings of molecular mechanisms underlying synechiae and orofacial clefting and to correct diagnosing of incomplete or overlapping features in IRF6-related disorders. Additional multidisciplinary evaluations to establish the phenotypical extent of the IRF6-related disorder and to address family counseling should not only be focused on the surgical corrections of syngnathia and cleft palate, but also involve comprehensive otolaryngologic, audiologic, logopedic, dental, orthopedic, urological and psychological evaluations. [ABSTRACT FROM AUTHOR]

Popliteal pterygium syndrome (PPS) is a rare inherited disorder involving the face, limbs, and genitalia. The most prominent and handicapping deformity associated with this syndrome is Popliteal pterygium. Popliteal pterygium is a contracture band that extends from ischial tuberosity to calcaneum. It is a dense fibrous band difficult to correct surgically. We report a case of PPS with her two other family members diagnosed with Van der Woude syndrome. Single-stage surgical release is ineffective due to shortened neurovascular and surrounding soft tissues. Multimodality treatment with surgical release and motivated parents may help these children to rehabilitate., Competing Interests: There are no conflicts of interest., (Copyright: © 2024 Journal of the West African College of Surgeons.)

Objective: The purpose of this study was to report a new variant in the Interferon Regulatory Factor 6 gene (IRF6) and to determine phenotype-genotype correlations in a family segregating Van der Woude syndrome. Methods: A five-generation family of 80 individuals segregating VWS was investigated using a tabulated pedigree but considering that three individuals registered in the pedigree died shortly after birth, the final sample size was 77 individuals. Five individuals had a complete dental clinical examination and molecular analysis performed using direct sequencing of the exon 4 and an adjacent region with 23 base pairs of the IRF6 gene. Results: Features of VWS reported in family history were present in 36.4% (28/77) of all family members; of these 57% (16/28) had pits in the lower lip, 36% (10/28) had both pits and orofacial clefts and 7 % (2/28) had only orofacial clefts. Developmental dental anomalies were observed in three individuals. The sequence analysis of exon 4 of the IRF6 gene carried out for 4 family members revealed the presence of the SNP rs7552506 (c.175-5C> G) located in five base pairs before the start of exon. The analysis of exon 4 of the IRF6 gene also revealed a new variant c.269G>C (p.Ser90Thr) which causes exchange of the Serine amino acid residue for the Threonine residue. Conclusions: The c.269G>C(p.Ser90Thr) can interfere with multimeric interactions and with protein conformation that will be slightly destabilized, because the mutant residue is bigger than the wild-type residue. The phenotypic variations in the cases studied, despite carrying the same genetic mutation, suggest that distinct genetic modifiers operate on the formation of clefts and dental development.

Objective: This case-control study was conducted to determine the distribution of cleft lip and/or palate, its association with family history, syndromes and serous otitis media (SOM), and its relation with several risk factors. Methods: The case group comprised of 133 children born with cleft lip and/or palate, and the control was 133 non-cleft children born full-term. Data was collected including age, gender, origin and risk factors for cleft lip and palate from patients’ files, interviewing supervising doctors, and the patient. Data was then filled out into Excel and underwent statistical analysis using the Goodness of Fit Test and Chi-Square to determine the significance of the results. Results: Cleft lip and/or palate (CL/P) was slightly higher among males (51.9%). Combined cleft lip and palate (CLP) was the most common presentation (42.1%). Cleft lips (CL) were mostly complete cleft (51,5%) incomplete cleft comprised (41.1%), In the sample 35.4% of the cases were bilateral, 32.3% were right unilateral, 28.3% were left unilateral and 4% were median cleft. Cleft palate (CP) was mostly complete (46.6%) there were incomplete clefts (40%), and the remainder were submucosal (13.4%). Isolated CL and combined CLP were higher in males (51.6%, 62.5% respectively). Both isolated CP and Tessier anomaly were more common in females (64.7% and 58.3% respectively). consanguineous marriages accounted for 36.1% of cases. 21.8% of the sample had a first-degree relative and 24.8% had a second degree relative born with CL/P. There were only 7 cases (0.05%) of syndromic CL/P: Down's (4), Pierre Robin's (2), and Van der Woude Syndrome (1). A relationship was found between CL/P and the risk factors: taking anticonvulsants (without specifying the drug) (p = 0.025, OR = 10.73 C.I. 95%), taking retinoic acid (p-value = 0.049, OR = 4.75 C.I. 95%), not consuming folic acid (p-value = 0.00, OR = 28.23 C.I. 95%), and smoking cigarettes (p-value = 0.046, OR = 2.00 C.I. 95%). There was no relationship with maternal alcohol consumption or maternal diabetes (p-values = 0.652 and 0.210, respectively). SOM was present in 63.2% of patients with CL/P and were mostly isolated CP. Conclusion: CL/P was only slightly higher among males. The most common condition was CLP. There was higher incidence of CL/P among second-degree relatives than first degree. Down's, Pierre Robin's, and Van der Woude Syndromes may be associated with CL/P. Taking anticonvulsants, taking retinoic acid, not consuming folic acid, and smoking cigarettes all have a role in the incidence of CL/P. More than half of the sample had an associated SOM.

Introduction: Van der Woude syndrome (VWS) is characterized by cleft palate, cleft lip, and lower-lip pits. Interferon regulatory factor 6 (IRF6) gene mutations have been reported as the cause of VWS. Subjects and Methods: Full stories of the affected individuals were obtained, and a pedigree analysis that goes back three-generation pedigree was performed. The IRF6 gene Sanger sequence analysis was performed on 43 affected individuals with ages ranging between 1 month and 84 years. Results: Our report comprises the molecular diagnosis of 43 patients with VWS in six different families. The c.841-2A>C mutation and the c.881T>A mutation are novel and have not been reported before. These novel mutations affect exon 7 of the IRF6 gene. Conclusion: The c.841-2A>C mutation is a splice site mutation, which is less common in the IRF6 gene and helps us understand the genomic structure better. A novel c.881T>A mutation was identified in exon 7. Due to variable expression, the same mutation can present itself in different clinical manifestations. However, different mutations in the same gene can also be observed through different phenotypes. Therefore, the clinical manifestations of new mutations can lead us to a better understanding of the causes of the disease. In addition, knowing the molecular cause of the disease is also useful for the surgical interventions.

Van der Woude syndrome (VWS) is the most common single gene mutation causing cleft lip/palate, responsible for approximately 2% of all cases. Inherited in an autosomal dominant pattern, VWS occurs at an incidence of 1 in 35,000 to 100,000. The most commonly reported manifestations of VWS is lip pits, cleft lip or palate. We present a case of a 34-week infant with unique and rarely reported symptoms of VWS, such as trismus and absent uvula.

Background: Van der Woude syndrome (VWS) is a rare congenital malformation characterized by lower lip pits among patients with a lip and/or palate cleft. It is transmitted by an autosomal dominant inheritance with variable expressivity., Methods: The study group consisted of 24 consecutive patients (13 males and 11 females) with VWS operated on at a single center between 2009 and 2022. They suffered from: bilateral cleft lip and palate - 6 patients; unilateral cleft lip and palate - 9 patients; cleft lip - 1 patient; and isolated cleft palate - 8 patients., Results: In 16 (66%) cases pits of lower lip occurred on both side of midline, while in 8 (34%) the pits were detected unilaterally. The primary cleft repairs were performed according to one-stage principle at the mean age of 8.6 months (SD 1.4, range 6-12). In all patients lower lip pits repairs were performed after the primary cleft repairs as a separate procedure at the mean age of 37 months (SD 11.3 range 14-85). The mean number of all primary repairs of the syndrome-both cleft defect and lower lip pits repairs-was 2.46. Nine patients (37.5%) required additional secondary corrections of the lower lip due to the poor aesthetic post-operative outcome., Conclusions: The frequent need for secondary corrections of residual lower lip deformities indicates the considerable difficulties in obtaining a satisfactory outcome of the repairs to lip pits caused by VWS. The average number of the primary surgical interventions in evaluated material remained low., (© 2024 Łukasz Wieprzowski et al., published by Sciendo.)

IRF6 is a key genetic determinant of syndromic and non-syndromic cleft lip and palate. The ability to interrogate post-embryonic requirements of Irf6 has been hindered, as global Irf6 ablation in the mouse causes neonatal lethality. Prior work analyzing Irf6 in mouse models defined its role in the embryonic surface epithelium and periderm where it is required to regulate cell proliferation and differentiation. Several reports have also described Irf6 gene expression in other cell types, such as muscle, and neuroectoderm. However, analysis of a functional role in non-epithelial cell lineages has been incomplete due to the severity and lethality of the Irf6 knockout model and the paucity of work with a conditional Irf6 allele. Here we describe the generation and characterization of a new Irf6 floxed mouse model and analysis of Irf6 ablation in periderm and neural crest lineages. This work found that loss of Irf6 in periderm recapitulates a mild Irf6 null phenotype, suggesting that Irf6 -mediated signaling in periderm plays a crucial role in regulating embryonic development. Further, conditional ablation of Irf6 in neural crest cells resulted in an anterior neural tube defect of variable penetrance. The generation of this conditional Irf6 allele allows for new insights into craniofacial development and new exploration into the post-natal role of Irf6 .

Van der Woude syndrome (VWS) is a genetic syndrome that leads to typical phenotypic traits, including lower lip pits and cleft lip/palate (CLP). The majority of VWS-affected patients harbor a pathogenic variant in the gene encoding for the transcription factor interferon regulatory factor 6 (IRF6), a crucial regulator of orofacial development, epidermal differentiation and tissue repair. However, most of the underlying mechanisms leading from pathogenic IRF6 gene variants to phenotypes observed in VWS remain poorly understood and elusive. The availability of one VWS individual within our cohort of CLP patients allowed us to identify a novel VWS-causing IRF6 variant and to functionally characterize it. Using VWS patient-derived keratinocytes, we reveal that most of the mutated IRF6_VWS transcripts are subject to a non-sense-mediated mRNA decay mechanism, resulting in IRF6 haploinsufficiency. While moderate levels of IRF6_VWS remain detectable in the VWS keratinocytes, our data illustrate that the IRF6_VWS protein, which lacks part of its protein-binding domain and its whole C-terminus, is noticeably less stable than its wild-type counterpart. Still, it maintains transcription factor function. As we report and characterize a so far undescribed VWS-causing IRF6 variant, our results shed light on the physiological as well as pathological role of IRF6 in keratinocytes. This acquired knowledge is essential for a better understanding of the molecular mechanisms leading to VWS and CLP.

Abstract Background The development of the face occurs during the early days of intrauterine life by the formation of facial processes from the first Pharyngeal arch. Derangement in these well‐organized fusion events results in Orofacial clefts (OFC). Van der Woude syndrome (VWS) is one of the most common causes of syndromic cleft lip and/or palate accounting for 2% of all cases. Mutations in the IRF6 gene account for 70% of cases with the majority of these mutations located in the DNA‐binding (exon 3, 4) or protein‐binding domains (exon 7–9). The current study was designed to update the list of IRF6 variants reported for VWS by compiling all the published mutations from 2013 to date as well as including the previously unreported VWS cases from Africa and Puerto Rico. Methods We used PubMed with the search terms; "Van der Woude syndrome," “Popliteal pterygium syndrome,” "IRF6," and "Orofacial cleft" to identify eligible studies. We compiled the CADD score for all the mutations to determine the percentage of deleterious variants. Results Twenty‐one new mutations were identified from nine papers. The majority of these mutations were in exon 4. Mutations in exon 3 and 4 had CADD scores between 20 and 30 and mutations in exon 7–9 had CADD scores between 30 and 40. The presence of higher CADD scores in the protein‐binding domain (exon 7–9) further confirms the crucial role played by this domain in the function of IRF6. In the new cases, we identified five IRF6 mutations, three novel missense mutations (p.Phe36Tyr, p.Lys109Thr, and p.Gln438Leu), and two previously reported nonsense mutations (p.Ser424*and p.Arg250*). Conclusion Mutations in the protein and DNA‐binding domains of IRF6 ranked among the top 0.1% and 1% most deleterious genetic mutations, respectively. Overall, these findings expand the range of VWS mutations and are important for diagnostic and counseling purposes.

BackgroundLoss-of-function mutations in interferon regulatory factor-6 (IRF6) are responsible for about 70% of cases of Van Der Woude Syndrome (VWS), an autosomal dominant developmental disorder characterized by pits and/or sinuses of the lower lip and cleft lip, cleft palate, or both.MethodsWe collected a Chinese Han VWS pedigree, performed sequencing and screening for the causal gene mutant. Initially, species conservation analysis and homology protein modeling were used to predict the potential pathogenicity of mutations. To test whether a VWS family-derived mutant variant of IRF6 retained function, we carried out rescue assays in irf6 maternal-null mutant zebrafish embryos. To assess protein stability, we overexpressed reference and family-variants of IRF6 in vitro.ResultsWe focused on a VWS family that includes a son with bilateral lip pits, uvula fissa and his father with bilateral cleft lip and palate. After sequencing and screening, a frameshift mutation of IRF6 was identified as the potential causal variant (NM.006147.3, c.1088-1091delTCTA; p.Ile363ArgfsTer33). The residues in this position are strongly conserved among species and homology modeling suggests the variant alters the protein structure. In irf6 maternal-null mutant zebrafish embryos the periderm differentiates abnormally and the embryos rupture and die during gastrulation. Injection of mRNA encoding the reference variant of human IRF6, but not of the frame-shift variant, rescued such embryos through gastrulation. Upon overexpression in HEK293FT cells, the IRF6 frame-shift mutant was relatively unstable and was preferentially targeted to the proteasome in comparison to the reference variant.ConclusionIn this VWS pedigree, a novel frameshift of IRF6 was identified as the likely causative gene variant. It is a lost function mutation which could not rescue abnormal periderm phenotype in irf6 maternal-null zebrafish and which causes the protein be unstable through proteasome-dependent degradation.

Abstract Background Interferon Regulatory Factor 6 (IRF6) gene encodes a member of the IRF family of transcription factors. Mutations in IRF6 cause Van der Woude Syndrome (VWS), which is the most common malformation of syndromic orofacial clefts in humans. Methods Here, we performed sequencing studies of six families with VWS in the Chinese Han population. The entire IRF6‐coding region and the exon–intron boundaries including exons 3–8 and part of exon 9 were screened among all the collected family members by Sanger sequencing. Results We found a novel splice site variant c.175‐6T>A, two novel missense variants (p.Lys66Arg and p.Pro107Thr), in addition with a previously reported missense variant (p.Leu87Phe), which were all located in and nearby exon 4 of IRF6. Meanwhile, a novel frameshift variant p.G257Vfs*46 in exon 7 of IRF6 was also detected. All the mutations presented to be co‐segregated in each family. Conclusion Our study has advanced the understanding of the genetic architecture of VWS and provides the basis for genetic counseling, antenatal diagnosis, and gene therapy of high risk groups.

Background: The development of the face occurs during the early days of intrauterine life by the formation of facial processes from the first Pharyngeal arch. Derangement in these well‐organized fusion events results in Orofacial clefts (OFC). Van der Woude syndrome (VWS) is one of the most common causes of syndromic cleft lip and/or palate accounting for 2% of all cases. Mutations in the IRF6 gene account for 70% of cases with the majority of these mutations located in the DNA‐binding (exon 3, 4) or protein‐binding domains (exon 7–9). The current study was designed to update the list of IRF6 variants reported for VWS by compiling all the published mutations from 2013 to date as well as including the previously unreported VWS cases from Africa and Puerto Rico. Methods: We used PubMed with the search terms; "Van der Woude syndrome," "Popliteal pterygium syndrome," "IRF6," and "Orofacial cleft" to identify eligible studies. We compiled the CADD score for all the mutations to determine the percentage of deleterious variants. Results: Twenty‐one new mutations were identified from nine papers. The majority of these mutations were in exon 4. Mutations in exon 3 and 4 had CADD scores between 20 and 30 and mutations in exon 7–9 had CADD scores between 30 and 40. The presence of higher CADD scores in the protein‐binding domain (exon 7–9) further confirms the crucial role played by this domain in the function of IRF6. In the new cases, we identified five IRF6 mutations, three novel missense mutations (p.Phe36Tyr, p.Lys109Thr, and p.Gln438Leu), and two previously reported nonsense mutations (p.Ser424*and p.Arg250*). Conclusion: Mutations in the protein and DNA‐binding domains of IRF6 ranked among the top 0.1% and 1% most deleterious genetic mutations, respectively. Overall, these findings expand the range of VWS mutations and are important for diagnostic and counseling purposes. [ABSTRACT FROM AUTHOR]

Introduction: Van der Woude syndrome (VWS) is characterized by cleft palate, cleft lip, and lower-lip pits. Interferon regulatory factor 6 (IRF6) gene mutations have been reported as the cause of VWS. Subjects and Methods: Full stories of the affected individuals were obtained, and a pedigree analysis that goes back three-generation pedigree was performed. The IRF6 gene Sanger sequence analysis was performed on 43 affected individuals with ages ranging between 1 month and 84 years. Results: Our report comprises the molecular diagnosis of 43 patients with VWS in six different families. The c.841-2A>C mutation and the c.881T>A mutation are novel and have not been reported before. These novel mutations affect exon 7 of the IRF6 gene. Conclusion: The c.841-2A>C mutation is a splice site mutation, which is less common in the IRF6 gene and helps us understand the genomic structure better. A novel c.881T>A mutation was identified in exon 7. Due to variable expression, the same mutation can present itself in different clinical manifestations. However, different mutations in the same gene can also be observed through different phenotypes. Therefore, the clinical manifestations of new mutations can lead us to a better understanding of the causes of the disease. In addition, knowing the molecular cause of the disease is also useful for the surgical interventions. [ABSTRACT FROM AUTHOR]

Background: Loss-of-function mutations in interferon regulatory factor-6 (IRF6) are responsible for about 70% of cases of Van Der Woude Syndrome (VWS), an autosomal dominant developmental disorder characterized by pits and/or sinuses of the lower lip and cleft lip, cleft palate, or both. Methods: We collected a Chinese Han VWS pedigree, performed sequencing and screening for the causal gene mutant. Initially, species conservation analysis and homology protein modeling were used to predict the potential pathogenicity of mutations. To test whether a VWS family-derived mutant variant of IRF6 retained function, we carried out rescue assays in irf6 maternal-null mutant zebrafish embryos. To assess protein stability, we overexpressed reference and family-variants of IRF6 in vitro. Results: We focused on a VWS family that includes a son with bilateral lip pits, uvula fissa and his father with bilateral cleft lip and palate. After sequencing and screening, a frameshift mutation of IRF6 was identified as the potential causal variant (NM.006147.3, c.1088-1091delTCTA; p.Ile363ArgfsTer33). The residues in this position are strongly conserved among species and homology modeling suggests the variant alters the protein structure. In irf6 maternal-null mutant zebrafish embryos the periderm differentiates abnormally and the embryos rupture and die during gastrulation. Injection of mRNA encoding the reference variant of human IRF6, but not of the frame-shift variant, rescued such embryos through gastrulation. Upon overexpression in HEK293FT cells, the IRF6 frame-shift mutant was relatively unstable and was preferentially targeted to the proteasome in comparison to the reference variant. Conclusion: In this VWS pedigree, a novel frameshift of IRF6 was identified as the likely causative gene variant. It is a lost function mutation which could not rescue abnormal periderm phenotype in irf6 maternal-null zebrafish and which causes the protein be unstable through proteasome-dependent degradation. [ABSTRACT FROM AUTHOR]

Background: Interferon Regulatory Factor 6 (IRF6) gene encodes a member of the IRF family of transcription factors. Mutations in IRF6 cause Van der Woude Syndrome (VWS), which is the most common malformation of syndromic orofacial clefts in humans. Methods: Here, we performed sequencing studies of six families with VWS in the Chinese Han population. The entire IRF6‐coding region and the exon–intron boundaries including exons 3–8 and part of exon 9 were screened among all the collected family members by Sanger sequencing. Results: We found a novel splice site variant c.175‐6T>A, two novel missense variants (p.Lys66Arg and p.Pro107Thr), in addition with a previously reported missense variant (p.Leu87Phe), which were all located in and nearby exon 4 of IRF6. Meanwhile, a novel frameshift variant p.G257Vfs*46 in exon 7 of IRF6 was also detected. All the mutations presented to be co‐segregated in each family. Conclusion: Our study has advanced the understanding of the genetic architecture of VWS and provides the basis for genetic counseling, antenatal diagnosis, and gene therapy of high risk groups. [ABSTRACT FROM AUTHOR]

Van der Woude Syndrome (VWS) is a rare autosomal dominant disorder with high penetrance and variable expressivity. The condition occurs in about 1:100,000–1:40,000 stillborn or live births and is characterized by lower lip pits, cleft lip, and/or cleft palate. Associated features of VWS include ankyloglossia, high arched palate, limb anomalies, congenital heart defects bifid uvula and syngnathia. We report four interesting cases of VWS with orofacial features. None of the four patients had any family history of lip pits, cleft lip, and/or cleft palate. The first patient with VWS showed a fusion of primary mandibular anterior teeth and the fourth patient demonstrated a supernumerary mandibular incisor. These features are very unusual in patients with VWS.

To gain more understanding of the complex molecular processes underlying cleft lip/palate (CLP), we established a unique human cell bank, consisting of keratinocytes and corresponding fibroblasts from individual CLP patients as a new study tool. After their careful characterization, we used such patient-derived cell cultures as well as control keratinocytes for in vitro differentiation and proliferation assays. Foreskin-derived control cells as a group showed significant higher induction of the late differentiation markers Loricrin and Filaggrin than the group of CLP patients-derived keratinocytes. Additionally, we detected great variations between individual CLP keratinocyte cell cultures in regard to their potential to terminally differentiate as assessed by the induction of Loricrin and Filaggrin. Primary patient cell cultures that did not properly differentiate, exhibited high proliferation rates. Moreover, we could correlate the expression levels of transcription factor IRF6 to the ability of individual cell cultures to terminally differentiate. Using clinically relevant, patient-derived cells, our results suggest that some of the genetic predispositions causing CLP might also lead to deficiencies in keratinocyte differentiation manifested in in vitro assays.

Cleft lip and palate is the most common congenital disorder affecting facial region. Van der Woude syndrome is a rare autosomal dominant disorder characterized by varying degree of cleft lip and/or palate, distinctive pits on the lower lip and hypodontia. A case of Van der Woude syndrome treated successfully with fixed orthodontic treatment is presented. The main feature of treatment planning and execution included moving the premaxilla to midline with gentle orthodontic force.

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To gain more understanding of the complex molecular processes underlying cleft lip/palate (CLP), we established a unique human cell bank, consisting of keratinocytes and corresponding fibroblasts from individual CLP patients as a new study tool. After their careful characterization, we used such patient-derived cell cultures as well as control keratinocytes for in vitro differentiation and proliferation assays. Foreskin-derived control cells as a group showed significant higher induction of the late differentiation markers Loricrin and Filaggrin than the group of CLP patients-derived keratinocytes. Additionally, we detected great variations between individual CLP keratinocyte cell cultures in regard to their potential to terminally differentiate as assessed by the induction of Loricrin and Filaggrin. Primary patient cell cultures that did not properly differentiate, exhibited high proliferation rates. Moreover, we could correlate the expression levels of transcription factor IRF6 to the ability of individual cell cultures to terminally differentiate. Using clinically relevant, patient-derived cells, our results suggest that some of the genetic predispositions causing CLP might also lead to deficiencies in keratinocyte differentiation manifested in in vitro assays. [ABSTRACT FROM AUTHOR]

Background Genome-wide linkage analysis and whole genome sequencing in a Van der Woude syndrome (VWS) family revealed that the SNP, rs539075, within intron 2 of the cadherin 2 gene ( CDH2 ) co-segregated with the disease phenotype. Results A study with nonsyndromic cleft lip with or without cleft palate (NSCL ± P) cases (N = 292) and controls (N = 287) established association of this SNP with NSCL ± P as a risk factor. RT-PCR based expression analysis of the SNP-harbouring region of intron 2 of CDH2 in the clefted lip and/or palate tissues of 16 patients revealed that the mutant allele expressed in all those individuals having it (hetero-/homozygous), whereas the wild type allele expressed in <50% of the samples in which it was present. The intronic transcript was also present in the prospective lip and palate region of 13.5 dpc mouse embryo, detected by RNA in situ hybridization and RT-PCR. Conclusions These results including the in silico , characterization of the ~200 nt-intronic transcript showed that conformationally it fits best with noncoding small RNA, possibly a precursor of miRNA. Its function in the orofacial organogenesis remains to be elucidated which will enable us to define the role of this mutant ncRNA in the clefting of lip and palate. [ABSTRACT FROM AUTHOR]

Van der Woude syndrome (VWS) shows an autosomal dominant pattern of inheritance with two known candidate genes, IRF6 and GRHL3. In this study, by employing genome-wide linkage analyses on two VWS affected families, we report the cosegregation of an intronic rare variant in NOL4 in one family, and a haplotype consisting of three variants in the noncoding region of IRF6 (introns 1, 8 and 3′UTR) in the other family. Using mouse, as well as human embryos as a model, we demonstrate the expression of NOL4 in the lip and palate primordia during their development. Luciferase, as well as miRNA-transfection assays show decline in the expression of mutant NOL4 construct due to the creation of a binding site for hsa-miR-4796-5p. In family 2, the noncoding region IRF6 haplotype turns out to be the candidate possibly by diminishing its IRF6 expression to half of its normal activity. Thus, here we report a new candidate gene (NOL4) and a haplotype of IRF6 for VWS, and highlight the genetic heterogeneity of this disorder in the Indian population. [ABSTRACT FROM AUTHOR]

Van der Woude syndrome (VWS) is a very rare congenital abnormality with high degree of penetrance and variable phenotypic expression. Common phenotypic features reported in the literature include bifid uvula, submucous cleft palate, or cleft palate to incomplete and complete unilateral or bilateral cleft lip and palate with lower lip pits as cardinal feature. Bilateral, single median or paramedian pits have been reported. We present an unusual VWS in both mother and child with the mother presenting with double bilateral (four) lower lip pits.

Background: Van der Woude syndrome (VWS), an autosomal dominant condition associated with clefts of the lip and/or palate and lower lip pits and is caused by mutations in interferon regulatory factor six gene. It is reported to be the most common syndromic cleft world-wide. Non-penetrance for the lip pit phenotype is found in at least 10% of affected individuals and those without the pits are phenocopies for non-syndromic clefting. The aim of this study is to present the phenotypic characteristic of VWS seen at the Lagos University Teaching Hospital (LUTH) cleft clinic. Materials and Methods: A review of cases of patients with VWS that attended the cleft lip and palate clinic at the LUTH Idi-Araba, Lagos, from January 2007 to December 2012 was conducted. Data analyses included sex of affected patients, types of cleft, presence of lower lip pits and history of lower lip pits/cleft in the family. Results: A total of 11 cases were seen during the period (male = 4; female = 7). Age at presentation ranged between 1 week and 12 years, with majority (n = 10) less than 2 years of age. Bilateral cleft lip and palate (BCLP) was seen in six patients, isolated soft palatal cleft (n = 3) and unilateral cleft lip and alveolus (n = 1) and cleft of hard and soft palate (n = 1). Bilateral lower lips were presented in 10 out of the 11 cases. The mother of the only patient without lip pits presented with bilateral lower lip pits. No family history of cleft/lip pits was elicited in 10 other cases. Conclusion: Most of the cases of VWS presented with BCLP and lower lip pits. Non-penetrance for the lip pits was seen in one out of 11 cases. Our study emphasizes the need to screen family members in all cleft cases, especially clinically diagnosed non-syndromic cases who may be VWS with no lip pits. Future studies are required to investigate the genetic causes of this syndrome in our population.

Background Orofacial clefts are congenital malformations of the orofacial region, with a global incidence of one per 700 live births. Interferon Regulatory Factor 6 ( IRF6) ( OMIM:607199) gene has been associated with the etiology of both syndromic and nonsyndromic orofacial clefts. The aim of this study was to show evidence of potentially pathogenic variants in IRF6 in orofacial clefts cohorts from Africa. Methods We carried out Sanger Sequencing on DNA from 184 patients with nonsyndromic orofacial clefts and 80 individuals with multiple congenital anomalies that presented with orofacial clefts. We sequenced all the nine exons of IRF6 as well as the 5′ and 3′ untranslated regions. In our analyses pipeline, we used various bioinformatics tools to detect and describe the potentially etiologic variants. Results We observed that potentially etiologic exonic and splice site variants were nonrandomly distributed among the nine exons of IRF6, with 92% of these variants occurring in exons 4 and 7. Novel variants were also observed in both nonsyndromic orofacial clefts (p.Glu69Lys, p.Asn185Thr, c.175-2A>C and c.1060+26C>T) and multiple congenital anomalies (p.Gly65Val, p.Lys320Asn and c.379+1G>T) patients. Our data also show evidence of compound heterozygotes that may modify phenotypes that emanate from IRF6 variants. Conclusions This study demonstrates that exons 4 and 7 of IRF6 are mutational 'hotspots' in our cohort and that IRF6 mutants-induced orofacial clefts may be prevalent in the Africa population, however, with variable penetrance and expressivity. These observations are relevant for detection of high-risk families as well as genetic counseling. In conclusion, we have shown that there may be a need to combine both molecular and clinical evidence in the grouping of orofacial clefts into syndromic and nonsyndromic forms. [ABSTRACT FROM AUTHOR]

Lip pits are rare congenital anomalies that are recorded on the upper lip, lower lip or the oral commissures. Recognition of this entity is important because of their association with other multiple anomalies. Proper evaluation and treatment of these associated abnormalities and genetic counseling is of utmost importance. Herewith, a rare case of isolated congenital lower lip pits is reported with a brief review of the literature.

One of the rarest developmental malformations of the lip is congenital lip pits. They are usually seen as bilateral depressions in the vermilion zone of the lip and occur on the paramedian portion of the vermilion border of the lip. They are extremely rare in the upper lip. Lip pits are due to the failure of complete union of embryonic lateral sulci of the lip/notching of lip at an early stage of development with fixation of tissues of the base of the notch. Lip pits have also been associated with a variety of other congenital disorders and other malformations. The clinical and pathologic picture and the therapeutic aspects of this condition are discussed in this paper.

Clefts of the lip and palate are a common craniofacial anomaly, The etiology is thought to be multifactorial, with both genetic and environmental factors playing a role. Because of the frequent manifestation of cleft lip and palate in association with some syndromes, it is essential that a detailed examination of these patients be carried out. This facilitates early formulation of preventive and treatment advice and aids in overcoming gross deformities in the early stages of development. In this paper, we review three such patients who presented with cleft lip and palate in association with a syndrome.

Background: Van der Woude syndrome (VWS), characterised mainly by lower lip pits and orofacial cleft (OFC), is the most common syndrome associated with an OFC. It is inherited as an autosomal dominant, high penetrance disorder with variable phenotypic expression and caused by the genetic mutation of the interferon regulatory factor 6 gene (IRF6). This study showcases the syndrome's variable phenotypic expressivity in six cases seen at Chu d' Treichvile, Abidjan, and Cote d'Ivoire., Materials and Methods: A review of six cases at the above-named hospital. Data collected include age at presentation, gender, type of cleft, presence or absence of lip pits, and family history of VWS., Results: Six cases of VWS were reviewed with an age range from 2 to 39 years and a male-to-female ratio of 1:2. Three of the patients had a bilateral cleft lip, one case of unilateral cleft lip and palate, another single case of cleft palate only while the sixth patient has no cleft deformity. All the patients have bilateral lower lip pits except one with a single median pit on the lower lip. There is a family history of VWS in three of the patients., Conclusion: Our study demonstrates the variable expressivity of VWS as different forms of lower lip pits and OFC. The presence of lower lip pits should be a signal for examination of family members to identify other cases and those likely to have cleft babies. Genetic mapping to detect mutation of IRF6 genes will be of tremendous aid in the effective diagnosis of VWS., Competing Interests: There are no conflicts of interest., (Copyright: © 2023 Journal of West African College of Surgeons.)

Introduction Van der Woude syndrome (VWS) is the most frequent form of syndromic cleft lip and palate (SCLP) accounting for 2% of all patients with CLP. Case presentation We describe the orthodontic treatment of a girl diagnosed with VWS referred by her family dentist for her cosmetic concerns. Discussion Comprehensive orthodontic treatment, secondary bone graft, distraction osteogenesis (for a deficient maxilla), secondary palatoplasty and excision of lower lip pits, as well as orthodontic and prosthetic procedures may provide a satisfactory outcome. Genetic testing showed a known putative splice site mutation (c.174 + 1 G/A) as the prime cause of VWS in our patient and her family. Conclusion SCLP has significant effects on facial aesthetics and the psychosocial status. Parents should be assessed and counseled appropriately. This condition is treatable in the absence of life threatening systemic anomalies. An interdisciplinary team approach is advocated. [ABSTRACT FROM AUTHOR]

Cleft lip with or without cleft palate (CL/P) is one of the most common birth defects worldwide and is characterized by abnormalities of the orofacial structure. Syndromic CL/P is mainly caused by Mendelian disorders such as Van der Woude Syndrome (VWS). However, > 70% of CL/P cases are nonsyndromic, characterized by isolated orofacial cleft without any known syndrome. The etiology of nonsyndromic CL/P (NSCL/P) remains elusive, but it has been suggested that causative genes of syndromic CL/P might also contribute to NSCL/P. As such, the VWS causative gene IRF6 has been extensively studied in NSCL/P. Recently, GRHL3 was identified as another VWS causative gene. Thus, it may be a novel candidate gene for NSCL/P. In the present study, we genotyped 10 tag SNPs covering GRHL3 and performed association analysis with NSCL/P in 504 cases and 455 healthy controls. Our preliminary results identified rs10903078, rs4638975, and a haplotype rs10903078-rs6659209 of GRHL3 that exceeded the significance threshold (p < 0.05), though none survived Bonferroni correction for multiple comparisons. As the first study between GRHL3 and NSCL/P, the contribution of this gene to NSCL/P etiology should be interpreted with caution based on existing evidence. Further, the robustness of association between GRHL3 and NSCL/P should be further validated in expanded cohorts. [ABSTRACT FROM AUTHOR]