OBJECTIVE: Van der Woude Syndrome (VWS) presents with combinations of lip pits (LP) and cleft lip and/or cleft palate (CL/P, CPO). VWS phenotypic heterogeneity even amongst relatives, suggests that epigenetic factors may act as modifiers. IRF6, causal for 70% of VWS cases, and TP63 interact in a regulatory loop coordinating epithelial proliferation and differentiation in palatogenesis. We hypothesize that differential DNA methylation within IRF6 and TP63 regulatory regions underlie VWS phenotypic discordance.
METHODS: DNA methylation of CpG sites in IRF6 and TP63 promoters and in an IRF6 enhancer element was compared amongst blood or saliva DNA samples of 78 unrelated cases. Analyses were done separately for blood and saliva, within each sex and in combination, and to address cleft type (CL/P ± LP vs. CPO ± LP) and phenotypic severity (any cleft + LP vs. any cleft only).
RESULTS: For cleft type, blood samples showed higher IRF6 and TP63 promoter methylation on males with CPO ± LP compared to CL/P ± LP and on individuals with CPO ± LP compared to those with CL/P ± LP, respectively. Saliva samples showed higher IRF6 enhancer methylation on individuals with CPO ± LP compared to CL/P ± LP and contrary to above, lower TP63 promoter methylation on CPO ± LP compared to CL/P ± LP. For phenotypic severity, blood samples showed no differences; however, saliva samples showed higher IRF6 promoter methylation in individuals with any cleft + LP compared to those without lip pits.
CONCLUSIONS: We observed differential methylation in IRF6 and TP63 regulatory regions associated with cleft type and phenotypic severity, indicating that epigenetic changes in IRF6 and TP63 can contribute to phenotypic heterogeneity in VWS.

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.

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.

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.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.

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.

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.
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.
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.
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.

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.
METHODS: 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.

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.

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.
CONCLUSIONS: 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.