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Background: Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a prevalent craniofacial birth defect on a global scale. A number of candidate genes have been identified as having an impact on NSCL/P. However, the association between interferon regulatory factor 6 (IRF6) polymorphisms and NSCL/P has yielded inconsistent results, prompting the need for a meta-analysis to obtain more accurate estimates., Methods: We conducted a thorough screening of all relevant articles published up until November 15, 2023, in online bibliographic databases. The statistical analysis of the collected data was performed using the Comprehensive Meta-Analysis (Version 4.0) software., Results: A total of 79 case-control studies, comprising 14,003 cases and 19,905 controls, were included in our analysis. The combined data indicated that the IRF6 rs642961 and rs2235371 polymorphisms were associated with an increased risk of NSCL/P in the overall population. However, no significant association was found between the rs2013162 and rs2235375 polymorphisms and the risk of NSCL/P in the overall population. Furthermore, subgroup analyses revealed significant correlations between the IRF6 rs642961, rs2235371, and rs2235375 polymorphisms and the risk of NSCL/P based on ethnic background and country of origin. Nevertheless, the rs2013162 polymorphism plays a protective role in Caucasians and mixed populations., Conclusions: Our collective data indicates a significant association between the rs642961 and rs2235371 polymorphisms and the risk of NSCL/P in the overall population. The rs2235375 polymorphism could influence the susceptibility to NSCL/P based on ethnic background. Meanwhile, the rs2013162 polymorphism provides protective effects in Caucasian, mixed populations, and the Brazilian population., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

The purpose of this study is to analyze the clinical characteristics of patients with Van der Woude syndrome (VWS) and to detect variations in each patient. Finally, the combination of genotype and phenotype can make a clear diagnosis of VWS patients with different phenotype penetrance., Five Chinese VWS pedigree were enrolled. Whole exome sequencing of the proband was performed, and the potential pathogenic variation was further verified by Sanger sequencing in the patient and their parents. The human mutant IRF6 coding sequence was generated from the human full-length IRF6 plasmid by site-directed mutagenesis and cloned into the GV658 vector, RT-qPCR and Western blot were used to detect the expression of IRF6 ., We found one de novo nonsense variation (p. Gln118Ter) and three novel missense variations (p. Gly301Glu, p. Gly267Ala, and p. Glu404Gly) co-segregated with VWS. RT-qPCR analysis revealed that p. Glu404Gly significantly reduced the expression level of IRF6 mRNA. Western blot of cell lysates confirmed that IRF6 p. Glu404Gly abundance levels were lower than those for IRF6 wild type., This discovery of the novel variation ( IRF6 p. Glu404Gly) expands the spectrum of known variations in VWS in Chinese humans. Genetic results combined with clinical phenotypes and differential diagnosis points from other diseases can make a definitive diagnosis and provide genetic counseling for families., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives: Considering limitations of previous studies and differences across populations and subtypes, this study aimed to identify new potential SNPs around IRF6 associated with non-syndromic orofacial cleft (NSOC) in Western Han Chinese., Materials and Methods: We recruited 376 NSOC case-parent trios, including 125 non-syndromic cleft lip only (NSCLO) trios, 151 non-syndromic cleft lip and palate (NSCLP) trios, and 100 non-syndromic cleft palate only (NSCPO) trios. Twenty-two single-nucleotide polymorphisms (SNPs) were genotyped using MassARRAY method. Hardy-Weinberg equilibrium test, allelic transmission disequilibrium test (TDT) analysis, sliding-window haplotype TDT analysis, and tests for parent-of-origin effect were performed using the PLINK software. Pairwise linkage disequilibrium (LD) was computed using the Haploview program., Results: In TDT analysis, allele A at rs17015217 (p = 0.00011, OR = 0.61 and 95% CI: 0.47-0.78) and allele T at rs12080691 (p = 0.00011, OR = 0.61 and 95% CI: 0.47-0.78) were under-transmitted among NSCLO trios but over-transmitted among NSCPO trios. Haplotypes showing evidence of under-transmission in NSCLO trios were over-transmitted in NSCPO trios. In tests for parent-of-origin effects, T allele at rs12080691 presented paternal under-transmission among NSCLO trios but over-transmission among NSCPO trios., Conclusions: Allele A at rs17015217 and allele T at rs12080691 are associated with NSCLO and NSCPO with potential to have opposite effects on two subtypes in this sample from Western Han Chinese., (© 2021 Wiley Periodicals LLC.)

Aims: Van der Woude syndrome (VWS) is one of the most common craniofacial anomalies, causing significant functional and psychological burden to the patients. This study aimed to identify the genetic cause of VWS in a Chinese family., Methods: Whole genome sequencing (WGS) was performed to screen for pathogenic mutations. Various Bioinformatics tools were used to assess the pathogenicity of the variants. Cosegregation analysis of the candidate variant was carried out. Interpretation of variants was performed according to the American College of Medical Genetics and Genomics guidelines., Results: A novel frameshift duplication c.373_374dupAA (p.Asn125Lys fs*43) was identified in exon 4 of the interferon regulatory factor 6 (IRF6) gene in all 3 affected members, which were not found in unaffected family members. The novel mutation leads to a frameshift and a premature stop codon which caused putative truncated protein. Protein alignment indicated high evolutionary conservation of the p.N125 residue, and this mutation was predicted by online tools to be damaging and deleterious., Conclusions: This study demonstrates that the novel mutation c.373_374dupAA (p.Asn125Lysfs*43) in the IRF6 gene corresponds to the VWS in this family. The discovery of this pathogenic variant enriches the genotypic spectrum of IRF6 gene and contributes to genetic diagnosis and counseling of families with VWS.

To date, the involvement of various genetic markers in the aetiopathogenesis of non-syndromic orofacial cleft (nsOFC) has been extensively studied. In the present study, we focused on studies performed on populations of European ancestry to systematically review the available literature to define relevant genetic risk factors for nsOFC. Eligible studies were obtained by searching Ovid Medline and Ovid Embase. We gathered the genetic markers from population-based case-control studies on nsOFC, and conducted meta-analysis on the repeatedly reported markers. Whenever possible, we performed stratified analysis based on different nsOFC phenotypes, using allelic, dominant, recessive and overdominant genetic models. Effect sizes were expressed as pooled odds ratios (ORs) with 95% confidence intervals (CIs), and p ≤ 0.05 were considered statistically significant. A total of 84 studies were eligible for this systematic review, with > 700 markers included. Of these, 43 studies were included in the meta-analysis. We analysed 47 genetic variants in 30 genes/loci, which resulted in 226 forest plots. There were statistically significant associations between at least one of the nsOFC phenotypes and 19 genetic variants in 13 genes/loci. These data suggest that IRF6, GRHL3, 8q24, VAX1, TGFA, FOXE1, ABCA4, NOG, GREM1, AXIN2, DVL2, WNT3A and WNT5A have high potential as biomarkers of nsOFC in populations of European descent. Although other meta-analyses that included European samples have been performed on a limited number of genetic variants, this study represents the first meta-analysis of all genetic markers that have been studied in connection with nsOFC in populations of European ancestry., (© 2022. The Author(s).)

Background: During the early embryological development of the face, complex orofacial failure results in a non-syndromic cleft lip and palate (NS CLP). The interferon regulatory factor 6 gene (IRF6) rs2235371 is a non-synonymous polymorphism that is one of the strong candidate genes associated with NS CLP., Objectives: The purpose of this study was to determine IRF6 rs2235371 as a risk factor for NS CLP and its phenotypes, including complete unilateral cleft lip and palate (CUCLP), bilateral cleft lip and palate (BCLP), cleft lip only (CL), and cleft palate only (CP), as well as to examine the effect of the polymorphism on the IRF6 mRNA expression levels among the Deutero-Malay race in Indonesia., Material and Methods: This study used a case-control design and enrolled 264 samples, including 158 NS CLP cases (42 NS CUCLP, 34 NS BCLP, 33 NS CL, and 49 NS CP) and 106 control subjects. DNA was extracted from venous blood, and then subjected to polymerase chain reaction (PCR) and sequencing. The odds ratio (OR) was used to determine the risk factor for NS CLP and its phenotypes. The Livak, KruskalWallis and Mann-Whitney U tests were used to determine mRNA expression levels in the oral epithelium, followed by real-time quantitative PCR (RT-qPCR)., Results: Among all of the NS CLP cases, in the NS CP phenotype, OR for the A mutant allele and the GA genotype was 2,492 (p = 0.017) and 2,114 (p = 0.048), respectively. The IRF6 mRNA expression level of the GA genotype was higher in the NS CP subjects as compared to the GG genotype (p = 0.031)., Conclusions: The IRF6 rs2235371 polymorphism is associated with the NS CP phenotype in DeuteroMalay patients from Indonesia and it affects the IRF6 mRNA expression level.

Orofacial clefts are the most common congenital craniofacial birth defects. They occur from a failure in cell proliferation and fusion of neural crest cells of the lip buds and/or palatal shelves. In this study, we investigate the genetic basis and molecular mechanisms in primary cells derived from a cleft and lip palate patient presenting van der Woude syndrome (VWS). Since mutations in the integrin genes are widely correlated with VWS, Interferon Regulatory Factor 6 (IRF6) screening was conducted in a cohort of 200 participants presenting with orofacial anomalies. Primary fibroblastic cells derived from the upper right gingiva and palatal regions were isolated and two cellular populations from two participants were obtained: a control with no cleft phenotype and a patient with a cleft phenotype typical of van der Woude syndrome (VWS). IRF6 targeted sequencing revealed mutations in two distinct families. Our results showed no alteration in the viability of the CLP/VWS patient cells, suggesting the phenotype associate with the disease is not secondary to a defect in cell proliferation. We did however detect a significant decrease in the migratory ability of the CLP with Van der Woude syndrome (CLP/VWS) patient cells, which could account for the phenotype. When compared to normal cells, patient cells showed a lack of polarization, which would account for their lack of mobility. Patient cells showed protrusions all around the cells and a lack of defined leading edge. This was reflected with actin staining, WAVE2 and Arp2 around the cell, and correlated with an increase in Rac1 activation. Consistently with the increase in Rac1 activation, patient cells showed a loss in the maturation of focal adhesions needed for contractility, which also accounts for the lack in cell migration. Our findings give increased understanding of the molecular mechanisms of VWS and expands the knowledge of van der Woude syndrome (VWS) occurrence by providing a strong molecular evidence that CLP with Van der Woude syndrome (CLP/VWS) phenotype is caused by a defect in normal physiological processes of cells., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: To explore the genetic basis for a Chinese pedigree affected with non-syndromic cleft lip and cleft palate (NSCLP)., Methods: With informed consent obtained, members of the pedigree were subjected to clinical examination and history taking to exclude syndromic cleft lip and palate. One affected member was subjected to whole-exome sequencing and bioinformatics analysis. Candidate variant was verified by Sanger sequencing and co-segregation analysis of her family members and 100 unrelated healthy individuals., Results: Whole-exome sequencing and co-segregation analysis showed that all affected members of this pedigree have carried a heterozygous missense c.253A>G (p.Cys85Arg) variant in exon 4 of the IRF6 gene, which has co-segregated with the phenotype and was not found among the 100 unrelated healthy individuals., Conclusion: The missense c.253A>G variant in exon 4 of the IRF6 gene probably underlay the NSCLP in this pedigree.

Abstract: Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is the most common congenital craniofacial malformation, and its harmful effects on affected individuals and families are apparent. The causative genes and their mechanisms are not completely clear, although several studies have been conducted. Accordingly, in the present study, we recruited a Han Chinese family with hereditary NSCL/P to explore the possible causative variants of this disease using whole exome sequencing. Bioinformatics screening and analysis, mutation function prediction, species conservation analysis, and homology protein modeling were used to identify the variants and evaluate their influence. A mutation in the interferon regulatory factor 6 (IRF6) gene (c.961C>T; p.Val321Met) was detected as a candidate causative variant and predicted to be deleterious. The codon was found to be conserved in many species, and the residue change caused by this mutation changed the structure of IRF6 to a certain degree. The findings suggest that this IRF6 variant is probably the pathogenic cause of NSCL/P in this family. Our results further provide evidence that IRF6 variants play a role in the etiology of NSCL/P., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by Mutaz B. Habal, MD.)

Introduction: Non-syndromic orofacial clefts have a complex etiology due to the contribution from both genetic and environmental risk factors, as well as the interaction between them. Among the more than 15 susceptibility loci for non-syndromic orofacial clefts with considerable statistical and biological support, the IRF6 is the most validated gene by the majority of studies. Nonetheless, in genetically heterogeneous populations such as Brazilian, the confirmation of association between non-syndromic orofacial clefts and IRF6 common variants is not a consolidated fact and unrecognized IRF6 variants are poorly investigated., Objective: The aim of this study was to investigate the association of IRF6 polymorphisms with non-syndromic orofacial clefts development in a population from northeast Brazil., Methods: Blood samples of 186 non-syndromic orofacial clefts patients and 182 controls from Rio Grande do Norte, Brazil, were obtained to analyze IRF6 polymorphisms (rs2235371, rs642961, rs2236907, rs861019, and rs1044516) by real-time polymerase chain reaction. Non-syndromic orofacial clefts patients were classified in cleft lip and palate, cleft palate only and cleft lip only groups., Results: The genotype and allele frequencies of single nucleotide polymorphism rs2235371 in IRF6 showed significant differences in patients with cleft palate when compared to the controls, whereas no association was shown between rs642961, rs2236907, rs861019, and rs1044516 and non-syndromic orofacial clefts., Conclusion: The association found between rs2235371 and isolated cleft palate should be interpreted with caution due to the low number of individuals investigated, and more studies with larger sample size are needed to confirm these association. In addition, there is a lack of association of the rs642961, rs2236907 and rs861019 polymorphisms with non-syndromic orofacial clefts susceptibility., (Copyright © 2019 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.)

Orofacial cleft (OFC) is one of the most prevalent birth defects, leading to substantial and long-term burdens in a newborn's quality of life. Although studies revealed several genetic variants associated with the birth defect, novel approaches may provide additional clues about its etiology. Using the Center for Craniofacial and Dental Genetics project data ( n = 10,542), we performed linear mixed-model analyses to study the genetic compositions of OFC and investigated the dependence among identified loci using conditional analyses. To identify genes associated with OFC, we conducted a transcriptome-wide association study (TWAS) based on predicted expression levels. In addition to confirming the previous findings at four loci, 1q32.2, 8q24, 2p24.2 and 17p13.1, we untwined two independent loci at 1q32.2, TRAF3IP3 and IRF6 . The sentinel SNP in TRAF3IP3 (rs2235370, p -value = 5.15 × 10 -9 ) was independent of the sentinel SNP at IRF6 (rs2235373, r 2 < 0.3). We found that the IRF6 effect became nonsignificant once the 8q24 effect was conditioned, while the TRAF3IP3 effect remained significant. Furthermore, we identified nine genes associated with OFC in TWAS, implicating a glutathione synthesis and drug detoxification pathway. We identified some meaningful additions to the OFC etiology using novel statistical methods in the existing data.

The aim of this study was to assess the association between IRF6 single nucleotide polymorphisms and nonsyndromic cleft lip, with or without cleft palate (NSCL/P), in a Chilean population, based on a case-control sample and confirmed in a case-parent trio population. In a sample of 150 Chilean case-parent trios and 164 controls (cohort 1), we evaluated the association between three common IRF6 variants (rs764093, rs2236909, rs2235375) and NSCL/P using odds ratio (OR) for case-control and case-parent trios and in a combined OR of both designs. To confirm associations from the cohort 1, we increased the sample size to 215 triads and 320 controls (cohort 1 + cohort 2). The combined OR for the cohort 1 reveals that the rs2235375 C allele is associated with NSCL/P in Chile (OR 1.34; p = 0.013), which was supported by the results for the two cohorts (OR 1.29; p = 0.006). Bioinformatic prediction showed that this variant, located 27 bp downstream from IRF6 exon 6, potentially alters the splicing process and based on functional annotations is associated with a decrease of gene expression. We propose that the C allele of rs2235375 from IRF6 gene seems to be a risk factor for NSCL/P in a Chilean population. However, we cannot discard a population stratification bias in our findings. On the other hand, further studies are necessary to confirm the biological role of rs2235375 in IRF6 function at craniofacial development level.

Previous studies have suggested that pathogenic variants in interferon regulatoryse factor 6 (IRF6) can account for almost 70% of familial Van der Woude Syndrome (VWS) cases. However, gene modifiers that account for the phenotypic variability of IRF6 in the context of VWS remain poorly characterized. The aim of this study was to report a family with VWS with variable expressivity and to identify the genetic cause. A 4‑month‑old boy initially presented with cleft palate and bilateral lower lip pits. Examination of his family history identified similar, albeit milder, clinical features in another four family members, including bilateral lower lip pits and/or hypodontia. Peripheral blood samples of eight members in this three‑generation family were subsequently collected, and whole‑exome sequencing was performed to detect pathogenic variants. A heterozygous missense IRF6 variant with a c.1198C>T change in exon 9 (resulting in an R400W change at the amino acid level) was detected in five affected subjects, but not in the other three unaffected subjects. Moreover, subsequent structural analysis was indicative of damaged stability to the structure in the mutant IRF protein. Whole‑transcriptome sequencing, expression analysis and Gene Ontology enrichment analysis were conducted on two groups of patients with phenotypic diversity from the same family. These analyses identified significant differentially expressed genes and enriched pathways in these two groups. Altogether, these findings provide insight into the mechanism underlying the variable expressivity of VWS.

We present here the first reported case of a non-syndromic cleft lip and palate (NSCLP) in an HIV-exposed newborn of a mother on antiretroviral therapy (ART) in Indonesia. Genetic testing was performed to confirm a suspected genetic condition. Genomic DNA was extracted from the blood, and genetic variations of the interferon regulatory factor 6 (IRF6) rs642961 (Mspl) (G>A) and transforming growth factor alpha (TGFA) BamHI (rs11466297, A>C) and RsaI (rs3732248, C>T) were performed by PCR-RFLP and IRF6 gene analysis by PCR sequencing. Genotyping of DNA sequence variants in the IRF6 gene showed both parents had genotype GA, while the child had genotype GG (genotype wild type). There was no difference observed in the TGFA BamHI gene variant between the child and her mother and father that were wild-type polymorphisms (normal), while the Rsa1 polymorphisms of them were heterozygotes. A genetic variant of IRF6 might be a protective factor for NSCLP, while Rsa1 gene variant (A) allele can be considered to be the risk factor associated with NSCLP development. This case report also highlights the possible etiologic role of ART in NSCLP; therefore, early control of adverse effects of ART might be an important factor in decreasing the incidence of the congenital anomalies in HIV-infected children., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.)

Missense, nonsense, splice site and regulatory region variants in interferon regulatory factor 6 ( IRF6 ) have been shown to contribute to both syndromic and non-syndromic forms of cleft lip and/or palate (CL/P). We report the diagnostic evaluation of a complex multigeneration family of Honduran ancestry with a pedigree structure consistent with autosomal-dominant inheritance with both incomplete penetrance and variable expressivity. The proband's grandmother bore children with two partners and CL/P segregates on both sides of each lineage. Through whole-exome sequencing of five members of the family, we identified a single shared synonymous variant, located in the middle of exon 7 of IRF6 (p.Ser307Ser; g.209963979 G>A; c.921C>T). The variant was shown to segregate in the seven affected individuals and through three unaffected obligate carriers, spanning both sides of this pedigree. This variant is very rare, only being found in three (all of Latino ancestry) of 251,352 alleles in the gnomAD database. While the variant did not create a splice acceptor/donor site, in silico analysis predicted it to impact an exonic splice silencer element and the binding of major splice regulatory factors. In vitro splice assays supported this by revealing multiple abnormal splicing events, estimated to impact >60% of allelic transcripts. Sequencing of the alternate splice products demonstrated the unmasking of a cryptic splice site six nucleotides 5' of the variant, as well as variable utilization of cryptic splice sites in intron 6. The ectopic expression of different splice regulatory proteins altered the proportion of abnormal splicing events seen in the splice assay, although the alteration was dependent on the splice factor. Importantly, each alternatively spliced mRNA is predicted to result in a frame shift and prematurely truncated IRF6 protein. This is the first study to identify a synonymous variant as a likely cause of NS-CL/P and highlights the care that should be taken by laboratories when considering and interpreting variants.

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., (© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

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., (© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.)

Microdeletion of the entire interferon regulatory factory 6 (IRF 6) gene is a rare cause of Van der Woude syndrome (VDW) with only few cases reported in medical literature. Its occurrence in multiple affected members of a family is exceptional. The aim of this presentation was to describe a Central African family with typical VDW phenotype carrying an IRF6 gene deletion. Here we reported phenotype features of members of a Central African family with VDW syndrome consisting of labioalveolar cleft, depressions of the lower lip with labial fistulae (lip pits), submucosal clefts and cleft palate. Mutation analysis by means of multiplex ligation-dependent probe amplification and chromosomal microarray revealed a 374.070 kb, deletion encompassing the entire IRF6 gene in four affected family members. Microdeletion of the entire IRF6 gene causes the classical VDW syndrome phenotype.

Nonsyndromic orofacial cleft (NSOFC) is a severe birth defect that occurs early in embryonic development and includes the subtypes cleft palate only (CPO), cleft lip only (CLO) and cleft lip with cleft palate (CLP). Given a lack of specific genetic factor analysis for CPO and CLO, the present study aimed to dissect the landscape of genetic factors underlying the pathogenesis of these two subtypes using 6,986 cases and 10,165 controls. By combining a genome-wide association study (GWAS) for specific subtypes of CPO and CLO, as well as functional gene network and ontology pathway analysis, we identified 18 genes/loci that surpassed genome-wide significance (P < 5 × 10-8) responsible for NSOFC, including nine for CPO, seven for CLO, two for both conditions and four that contribute to the CLP subtype. Among these 18 genes/loci, 14 are novel and identified in this study and 12 contain developmental transcription factors (TFs), suggesting that TFs are the key factors for the pathogenesis of NSOFC subtypes. Interestingly, we observed an opposite effect of the genetic variants in the IRF6 gene for CPO and CLO. Moreover, the gene expression dosage effect of IRF6 with two different alleles at the same single-nucleotide polymorphism (SNP) plays important roles in driving CPO or CLO. In addition, PAX9 is a key TF for CPO. Our findings define subtypes of NSOFC using genetic factors and their functional ontologies and provide a clue to improve their diagnosis and treatment in the future., Competing Interests: The authors have declared that no competing interests exist.

The integrity of the mammalian epidermis depends on a balance of proliferation and differentiation in the resident population of stem cells 1 . The kinase RIPK4 and the transcription factor IRF6 are mutated in severe developmental syndromes in humans, and mice lacking these genes display epidermal hyperproliferation and soft-tissue fusions that result in neonatal lethality 2-5 . Our understanding of how these genes control epidermal differentiation is incomplete. Here we show that the role of RIPK4 in mouse development requires its kinase activity; that RIPK4 and IRF6 expressed in the epidermis regulate the same biological processes; and that the phosphorylation of IRF6 at Ser413 and Ser424 primes IRF6 for activation. Using RNA sequencing (RNA-seq), histone chromatin immunoprecipitation followed by sequencing (ChIP-seq) and assay for transposase-accessible chromatin using sequencing (ATAC-seq) of skin in wild-type and IRF6-deficient mouse embryos, we define the transcriptional programs that are regulated by IRF6 during epidermal differentiation. IRF6 was enriched at bivalent promoters, and IRF6 deficiency caused defective expression of genes that are involved in the metabolism of lipids and the formation of tight junctions. Accordingly, the lipid composition of the stratum corneum of Irf6 -/- skin was abnormal, culminating in a severe defect in the function of the epidermal barrier. Collectively, our results explain how RIPK4 and IRF6 function to ensure the integrity of the epidermis and provide mechanistic insights into why developmental syndromes that are characterized by orofacial, skin and genital abnormalities result when this axis goes awry.

Van der Woude syndrome (VWS) is a rare autosomal dominant disease, first reported in the literature in 1845 by Demarquay and subsequently thoroughly described in 1954 by Van der Woude. Van der Woude Syndrome is the most common form of syndromic orofacial clefting and individuals with this syndrome account for 2% of all cleft cases. Van der Woude syndrome clinically presents with congenital lip pits. These lip pits occur on paramedian portion of the vermillion border of the lip. In VWS, congenital lip pits occur in concurrence with cleft lip and/or cleft palate and represent the most common clinical problem occurring in 80% of the patients. Lip pits result due to notching of the lips at an early stage of development with fixation of tissues at the base of the notch or they may result from a failure of complete union of embryonic lateral sulci of lip. Single lip sinuses without any cleft syndrome are rare; lower lip fistulas in VWS are generally asymptomatic, and surgical management is usually accomplished because of aesthetic concerns. However, in some cases, patients may complain of watery drainage or hypotonia of the lower lip. Herein, the authors report a novel frameshift mutation in IRF6 gene which may contribute to better understanding the genetic aspect of VWS.

Objective: To analyze clinical and genetic features of a family affected with Van der Woude syndrome., Methods: The umbilical cord blood of the proband and the peripheral blood of the parents were used for the whole exon sequencing to find the candidate gene.Peripheral blood of 9 members of the family were collected for Sanger sequencing verification, bioinformatics analysis and genotype-phenotype correlation analysis., Results: The proband was diagnosed with cleft lip and palate by ultrasound. His father and grandmother had hollow lower lip and all other family members did not have the similar phenotype. A missense c.263A>G (p.N88S) mutation was found in exon 4 of IRF6 gene in the proband, his father and his grandmother.The mutation was not found in other family members., Conclusions: A missense c.263A>G (p.N88S) mutation in IRF6 gene probably underlies the pathogenesis of Van der Woude syndrome in the family and the mutation has been firstly discovered in China.

Background: Interferon regulatory factor 6 (IRF6) plays a critical role in embryonic tissue development, including differentiation of epithelial cells. Besides orofacial clefting due to haploinsufficiency of IRF6, recent human genetic studies indicated that mutations in IRF6 are linked to small mandible and digit abnormalities. The function of IRF6 has been well studied in oral epithelium; however, its role in craniofacial skeletal formation remains unknown. In this study, we investigated the role of Irf6 in craniofacial bone development using comparative analyses between wild-type (WT) and Irf6-null littermate mice., Results: Immunostaining revealed the expression of IRF6 in hypertrophic chondrocytes, osteocytes, and bone matrix of craniofacial tissues. Histological analysis of Irf6-null mice showed a remarkable reduction in the number of lacunae, embedded osteocytes in matrices, and a reduction in mineralization during bone formation. These abnormalities may explain the decreased craniofacial bone density detected by micro-CT, loss of incisors, and mandibular bone abnormality of Irf6-null mice. To validate the autonomous role of IRF6 in bone, extracted primary osteoblasts from calvarial bone of WT and Irf6-null pups showed no effect on osteoblastic viability and proliferation. However, a reduction in mineralization was detected in Irf6-null cells., Conclusions: Altogether, these findings suggest an autonomous role of Irf6 in regulating bone differentiation and mineralization. Developmental Dynamics 248:221-232, 2019. © 2019 Wiley Periodicals, Inc., (© 2019 Wiley Periodicals, Inc.)

Single-nucleotide polymorphisms (SNPs) in protein-coding regions of genes which were previously reported to be associated with nonsyndromic cleft lip, with or without palate involvement (NSCL/P), were investigated. Twelve candidate loci [platelet-derived growth factor C (PDGFC), platelet-derived growth factor subunit A (PDGFA), platelet-derived growth factor receptor alpha (PDGFRA), glycine receptor alpha 2 (GLRA2), glycine receptor beta (GLRB), ATP binding cassette subfamily A member 4 (ABCA4), MAF bZIP transcription factor B (MAFB), interferon regulatory factor 6 (IRF6), CCDC26 long non-coding RNA (CCDC26), paired box 7 (PAX7), ventral anterior homeobox 1 (VAX1), and netrin 1 (NTN1)] covering 1.5 Mbp were sequenced in 136 NSCL/P patients and 54 healthy controls. Twenty-five genomic variants identified were further validated in another 400 NSCL/P and 200 controls. Two SNPs in IRF6 showed a protective effect against the development of NSCL/P (rs12405750, OR = 0.54, 95% CI: 0.41-0.69; and rs2235371, OR = 0.55, 95% CI: 0.43-0.71). The missense variant, rs2235371, alters the conserved amino acid valine to isoleucine at codon 274 (V274I). We observed that SNPs at IRF6 (rs2235371 and rs12405750) and GLRB (rs73856838 and rs72685584) show consistent interaction effects. The association between the missense SNP rs2235371 in gene IRF6 and NSCL/P suggests that this SNP may play an important role as a risk factor for NSCL/P in the Han Chinese populations. The marginal signal near 4q31 detected in previous genome-wide association studies might be caused by an interaction between the IRF6 and GLRB genes. This interaction needs to be further validated by experimentation in follow-up studies., (© 2018 Eur J Oral Sci.)

Objective: Subjects with cleft lip and palate (CLP) present high prevalence of dental agenesis. Among candidate genes for these phenotypes is IRF6. However, genetic studies do not analyze dental agenesis as a phenotype associated with cleft. Therefore, we investigated the frequency of rare and novel variations in IRF6 in subjects with non-syndromic unilateral cleft lip and palate (NSUCLP), with and without dental agenesis., Subjects and Methods: Genomic DNA samples of 100 subjects with NSUCLP with and without dental agenesis and 50 controls were sequenced. IRF6 mutational screening was conducted by direct sequencing., Results: Ten new and rare missense variations were identified, two in the group cleft with agenesis and eight in the group cleft without agenesis, and none were found in control group. In silico analysis revealed four variations as potentially deleterious, being two in the group with cleft and agenesis and two in the group with cleft without agenesis., Conclusion: The study identified novel IFR6 variations in subjects with NSUCLP with or without associated dental agenesis. The hypothesis of a higher frequency of deleterious variations in the subjects with cleft associated with dental agenesis, when compared to the group of cleft without agenesis and control without cleft, was not supported., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.)

Objective: To examine the possible associations between methylation changes in the promoter regions of long interspersed nucleotide element-1 (LINE-1) and interferon regulatory factor 6 gene (IRF6) and nonsyndromic cleft lip with or without cleft palate (NSCL/P)., Methods: A case-control investigation was performed to compare 37 infants affected by NSCL/Ps with 60 babies without cleft malformations. Their genomic DNA samples were obtained, and the LINE-1 and IRF6 methylation levels were measured by using Sequenom MassArray. Unconditional logistic regression was adopted to estimate the odds ratio., Results: Infants with NSCL/Ps had a higher methylation level at LINE-1 and IRF6 promoter regions than controls. High levels of LINE-1 (≥64.07%) and IRF6 (≥6.46%) methylation were associated with an increased risk of NSCL/P (LINE-1, OR = 2.63, 95% CI: 1.07-6.57; IRF6, OR = 4.73, 95% CI: 2.10-13.07), and the associations remained to be significant after adjusting for potential confounders. Similar associations were also found for cleft lip only, cleft lip, and palate., Conclusion: Our study suggested that aberrant methylation of LINE-1 and IRF6 might contribute to the development of NSCL/Ps. Further studies are needed to replicate the findings., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.)

Variants in IRF6 can lead to Van der Woude syndrome and popliteal pterygium syndrome. Furthermore, genes upstream and downstream of IRF6, including GRHL3 and TP63, are also associated with orofacial clefting. Additionally, a variant in an enhancer (MCS9.7) that regulates IRF6 is associated with risk for isolated orofacial clefting. This variant (rs642961) abrogates AP2A protein binding at MCS9.7. Here, we found that AP2A protein regulates MCS9.7 enhancer activity in vivo and IRF6 protein expression in epidermal development. In addition, loss of IRF6 leads to supra-basal expression of AP2A protein. Finally, using an IRF6 allelic series, we found that either increasing or decreasing IRF6 protein expression can destabilize AP2A protein expression in vivo. These data suggest that IRF6 regulates AP2A protein level in epidermal development. Therefore, we conclude that IRF6 and TFAP2A are part of a genetic regulatory network that is critical in epithelial development, with implications for both orofacial and cutaneous tissues. Our work provides in vivo, functional data to explain the relationship between AP2A protein binding and the MCS9.7 enhancer in orofacial clefting. This work is important because the MCS9.7 enhancer element contains a variant that abrogates AP2A protein binding and increases risk for orofacial clefting worldwide., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: This study aimed to investigate the clinical phenotype and genetic characteristics of Chinese families with Van der Woude syndrome (VWS)., Methods: Clinical manifestations between 14 families and within each family were recorded. Possible inheritance modes and pathogenic genes were analyzed. Phenotypic distribution and gene frequencies were calculated., Results: Of the pedigrees investigated, an autosomal dominant inheritance pattern was suggested. All patients had typical symptoms. The pathogenic gene was interferon regulatory factor 6 (IRF6). Phenotypic distribution frequencies were as follows: lip pits (91.9%), cleft lip and/or palate (73.0%), and hyperdontia (8.1%). There were significant differences in clinical phenotypes among individuals of different families and individuals of the same family., Conclusions: VWS in a Chinese population was dominantly inherited with high penetrance and variable expressivity. The pathogenic gene was IRF6. VWS in a Chinese population was genotyped as VWS1.

Non-syndromic cleft lip with or without cleft palate (NSCLP) is the most common congenital craniofacial malformation, and its harmful influence on affected individuals is apparent. Despite many studies, the causative genes and their mechanisms are not completely clear. We recruited a Han Chinese NSCLP family and explored the causative variant in this pedigree. We performed whole-exome sequencing on two patients. Bioinformatics screening and analysis were used to identify the mutation. We also performed species conservation analysis, mutation function predictions, and homology protein modelling to evaluate the influence of the mutation. We identified a rare mutation in interferon regulatory factor 6 (IRF6) (c.26G>A; p.Arg9Gln) as a candidate of causative mutation. This mutation was predicted to be deleterious. The codon is conserved in many species. The residue change caused by this mutation would affect the structure of IRF6 to a degree. Our study suggested that the rare IRF6 variant is probably the pathogenic mutation in this family. Our result adds evidence that IRF6 variants play a role in the aetiology of orofacial clefts.

Introduction: Transcription factors are very diverse family of proteins involved in activating or repressing the transcription of a gene at a given time. Several studies using animal models demonstrated the role of transcription factor genes in craniofacial development., Objective: We aimed to investigate the association of IRF6 intron-6 polymorphism in the non-syndromic cleft lip with or without palate in a South Indian population., Methods: 173 unrelated nonsyndromic cleft lip with or without cleft palate patients and 176 controls without clefts patients were genotyped for IRF6 rs2235375 variant by allele-specific amplification using the KASPar single nucleotide polymorphism genotyping system. The association between interferon regulatory factor-6 gene intron-6 dbSNP208032210:g.G>C (rs2235375) single nucleotide polymorphism and non-syndromic cleft lip with or without palate risk was investigated by chi-square test., Results: There were significant differences in genotype or allele frequencies of rs2235375 single nucleotide polymorphism between controls and cases with non-syndromic cleft lip with or without palate. IRF6 rs2235375 variant was significantly associated with increased risk of non-syndromic cleft lip with or without palate in co-dominant, dominant (OR: 1.19; 95% CI 1.03-2.51; p=0.034) and allelic models (OR: 1.40; 95% CI 1.04-1.90; p=0.028). When subset analysis was applied significantly increased risk was observed in cleft palate only group (OR dominant: 4.33; 95% CI 1.44-12.97; p=0.005)., Conclusion: These results suggest that IRF6 rs2235375 SNP play a major role in the pathogenesis and risk of developing non-syndromic cleft lip with or without palate., (Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.)

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 forVWS, and highlight the genetic heterogeneity of this disorder in the Indian population.

Objective: Nonsyndromic clefts of the lip and/or palate (NSCL/P) are one of the most common polygenic diseases. Recently, many studies focused on the association between CRISPLD2 polymorphisms and NSCL/P risk. However, some studies have shown opposite results. In this study, meta-analysis was used to confirm whether CRISPLD2 polymorphism was associated with NSCL/P, and the possible mechanism between CRISPLD2 and NSCL/P was explored., Methods: Relevant studies were conducted on PubMed, Ovid, EBSCO, CINAHL, FMRS, Web of Science, CNKI, and Wanfang databases from their inception up to June 31, 2016. Review Manager 5.0.24 was used to analyze whether CRISPLD2 polymorphism was involved in NSCL/P by pooling odds ratios (ORs) and 95% confidence intervals (CIs). Potential publication bias was evaluated by visual inspection of the funnel plot., Results: CRISPLD2 rs4783099 was associated with cleft lip and/or palate (CL/P) statistically (OR = 3.18, P < .01). Compared to genotype TT, genotypes CC and CT were correlated significantly (OR = 2.04, P = .04) with CL/P. No evidence showed an association between genetic variation at the CRISPLD2 locus and cleft palate only (CP)., Conclusion: The polymorphism of CRISPLD2 rs4783099 is correlated with an increased risk of CL/P.

Objective: The interferon regulatory factor 6 gene (IRF6) is one of the most conspicuous genes among a large number of candidate risk genes for non-syndromic cleft lip with or without cleft palate, which is considered to be a multifactorial defect. Variants of IRF6 are also suggested to affect normal craniofacial variations, especially in the area of the nose and the upper lip. In the present study, we used lateral cephalograms to establish the relationship between IRF6 and sagittal nasolabial morphology in healthy East Asian subjects., Design: Genomic DNA was extracted from 215 Japanese and 226 Korean individuals, and genotyped for five IRF6 single nucleotide polymorphisms (SNPs): rs17389541, rs642961, rs2013162, rs2235371, and rs7802. These SNPs were tested by multiple regression analyses for their association with craniofacial measurements obtained from lateral cephalometrics., Results: We detected a significant association between the derived variants, rs2013162 and rs2235371 and the distances between a facial bone plane indicated by distance from Nasion and Point A (NA plane) to soft tissue landmarks; the Subalare (NA-Sbal) and the Subnasale (NA-Sn) in the sagittal plane., Conclusion: Our results indicate that IRF6 variants play an important role in the normal range of variation in nasolabial soft-tissue morphology., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objective: To investigate the association between the risk of nonsyndromic cleft lip with or without cleft palate (NSCL/P) and the IRF6 rs2235371 (C>T) polymorphism in Chinese Han populations., Design: PubMed, Web of Science and EMBASE were searched through May 31, 2016, to select eligible studies. Pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were applied to estimate the risk of NSCL/P associated with the IRF6 rs2235371 polymorphism. Subgroup analyses were conducted according to NSCL/P types (CLO, CPO and CLP) and the geographical location (Northern China and Southern China). Publication bias and sensitivity analyses were performed to assess the reliability of the results., Results: A total of 1275 NSCL/P cases and 1294 controls from seven eligible case-control studies were included. In the overall analysis, a significant association between the IRF6 rs2235371 polymorphism and the risk of NSCL/P was identified under all genetic models, with the exception of the recessive model (T vs. C: OR=0.68, 95%CI=0.60-0.76, P<0.00001). A subgroup analysis by NSCL/P types indicated that the variant T allele significantly decreased the risk of CLO and CLP but not CPO. A subgroup analysis of the geographical location further showed significantly decreased susceptibility in Northern China under all genetic models, but in Southern China, only the heterozygote and dominant models showed a significantly decreased risk of NSCL/P. Funnel plot analysis and the Egger linear regression method detected no publication bias., Conclusions: The IRF6 rs2235371 T allele decreased the risk of NSCL/P in Chinese Han populations. However, further studies with large sample sizes should be conducted to confirm this association., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: Non-syndromic cleft lip with or without palate (NSCL/P) is a common congenital malformation worldwide, with complex etiology. It has been proposed that interaction of genes and environmental factors play a role in the predisposition to this disease. The aim of this study was to examine the association between AXIN2 (axis inhibition protein 2) rs7224837, BMP4 (bone morphogenetic protein 4) rs17563, and IRF6 (interferon regulatory factor 6) rs861019 and 2235371 polymorphisms and NSCL/P in an Iranian population., Material and Methods: This case-control study was carried out on 132 unrelated NSCL/P patients and 156 healthy subjects. The variants were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)., Results: The findings suggest that BMP4 rs17563 polymorphism significantly decreased the risk of NSCL/P in codominant (OR=0.36, 95%CI=0.17-0.79, p=0.012, CT vs CC and OR=0.11, 95%CI=0.01-0.88, p = 0.019, TT vs CC), dominant (OR=0.30, 95%CI=0.15-0.62, p = 0.0007, CT+TT vs CC), recessive (OR=0.12, 95%CI=0.02-0.99, p = 0.023, TT vs CC+CT), overdominant (OR=0.39, 95%CI = 0.18-0.84, p=0.021, CT vs CC+TT), and allele (OR=0.28, 95%CI=0.15-0.55, p<0.0001, T vs C) inheritance models. Our findings did not support an association between AXIN2 rs7224837 and IRF6 rs861019 polymorphism and risk/protection of NSCL/P. The IRF6 2235371 variant was not polymorphic in our population., Conclusion: The results indicate that the BMP4 rs17563 variant is likely to confer a protective effect against the occurrence of NSCL/P in a sample of the southeast Iranian population.

Mutations and common polymorphisms in interferon regulatory factor 6 ( IRF6) are associated with both syndromic and nonsyndromic forms of cleft lip/palate (CLP). To date, much of the focus on this transcription factor has been on identifying its direct targets and the gene regulatory network in which it operates. Notably, however, IRF6 is found predominantly in the cytoplasm, with its import into the nucleus tightly regulated like other members of the IRF family. To provide further insight into the role of IRF6 in the pathogenesis of CLP, we sought to identify direct IRF6 protein interactors using a combination of yeast 2-hybrid screens and co-immunoprecipitation assays. Using this approach, we identified NME1 and NME2, well-known regulators of Rho-type GTPases, E-cadherin endocytosis, and epithelial junctional remodeling, as bona fide IRF6 partner proteins. The NME proteins co-localize with IRF6 in the cytoplasm of primary palatal epithelial cells in vivo, and their interaction with IRF6 is significantly enhanced by phosphorylation of key serine residues in the IRF6 C-terminus. Furthermore, CLP associated IRF6 missense mutations disrupt the ability of IRF6 to bind the NME proteins and result in elevated activation of Rac1 and RhoA, compared to wild-type IRF6, when ectopically expressed in 293T epithelial cells. Significantly, we also report the identification of 2 unique missense mutations in the NME proteins in patients with CLP (NME1 R18Q in an IRF6 and GRHL3 mutation-negative patient with van der Woude syndrome and NME2 G71V in a patient with nonsyndromic CLP). Both variants disrupted the ability of the respective proteins to interact with IRF6. The data presented suggest an important role for cytoplasmic IRF6 in regulating the availability or localization of the NME1/2 complex and thus the dynamic behavior of epithelia during lip/palate development.

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 ( Tg KRT14::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 +/- ;Tg KRT14::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.

Van der Woude syndrome (VWS) is a rare autosomal dominant genetic disorder characterized by orofacial clefting and lip pits. Mutations in the transcription factor interferon regulatory factor 6 gene (IRF6) have been identified in individuals with VWS. We performed direct sequencing of the gene for molecular investigation of a proband with Bangladeshi-Malay ancestry. A novel transition mutation (c.113T>C), which resulted in an amino acid substitution (p.Ile38Thr) in the deoxyribonucleic acid-binding domain was detected. Testing of family members showed that the mutation segregated with the VWS phenotype for members of her immediate family. Although there is some phenotypic variability, all of the affected members are of the female gender.

Objective: Interferon Regulatory Factor 6 (IRF6) is critical for craniofacial development, epidermal differentiation, and tissue repair. IRF6 mutations cause Van der Woude Syndrome (VWS) and Popliteal Pterygium Syndrome. Individuals with VWS exhibit craniofacial anomalies, including cleft lip and palate and lip pits. Furthermore, they have an increased risk for wound-healing complications following surgical repair when compared with patients with nonsyndromic cleft lip and palate (NSCLP). However, nothing is known about the skin of these patients. The objective was to characterize the skin of patients with VWS. We hypothesize that IRF6 is required for proper skin homeostasis in humans., Design: Discarded tissue from a hip was collected during surgical alveolar bone graft. Samples from children with VWS harboring IRF6 mutations (n = 2) were compared with samples from children with NSCLP (n = 7). Histology was assessed following hematoxylin and eosin staining. The expressions of Proliferating Cell Nuclear Antigen, IRF6, P63, and Keratin 10 were determined by immunofluorescence. Keratinocytes were isolated and their proliferation potential was assessed by colony-forming efficiency assay., Results: Hip skin from children with VWS showed a thicker epidermis when compared with that from children with NSCLP. Proliferating Cell Nuclear Antigen staining revealed an increase in proliferation in syndromic tissues when compared with controls. However, P63 and Keratin 10 expression were similar between groups. Finally, keratinocytes from VWS showed increased long-term proliferation when compared with NSCLP., Conclusions: These results support, in vivo and in vitro, a previously described role for IRF6 in epidermal proliferation in humans. They further demonstrate a critical function for IRF6 in cutaneous homeostasis.

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is the most common craniofacial birth defect in humans, the etiology of which can be dependent on the interactions of multiple genes. We previously reported haplotype associations for polymorphic variants of interferon regulatory factor 6 (IRF6), msh homeobox 1 (MSX1), bone morphogenetic protein 4 (BMP4), and transforming growth factor beta 3 (TGFB3) in Chile. Here, we analyzed the haplotype-based gene-gene interaction for markers of these genes and NSCL/P risk in the Chilean population. We genotyped 15 single nucleoptide polymorphisms (SNPs) in 152 Chilean patients and 164 controls. Linkage disequilibrium (LD) blocks were determined using the Haploview software, and phase reconstruction was performed by the Phase program. Haplotype-based interactions were evaluated using the multifactor dimensionality reduction (MDR) method. We detected two LD blocks composed of two SNPs from BMP4 (Block 1) and three SNPs from IRF6 (Block 2). Although MDR showed no statistical significance for the global interaction model involving these blocks, we found four combinations conferring a statistically significantly increased NSCL/P risk (Block 1-Block 2): T-T/T-G C-G-T/G-A-T; T-T/T-G C-G-C/C-G-C; T-T/T-G G-A-T/G-A-T; and T-T/C-G G-A-T/G-A-T. These findings may reflect the presence of a genomic region containing potential causal variants interacting in the etiology of NSCL/P and may contribute to disentangling the complex etiology of this birth defect., (© 2017 Eur J Oral Sci.)

Patients with cleft lip/palate (CLP) have been reported, in some studies, to exhibit an increased prevalence of caries, although the underlying cause for this increase is unknown. In genetically defined mouse models, studies of postnatal sequelae associated with CLP have been hampered by neonatal lethality. Using a conditional targeting approach, we ablated the major CLP gene Irf6 only in the late embryonic oral epithelium ( Irf6 cKO), bypassing the role of the gene in lip and palate morphogenesis and thus ensuring survival to adulthood. We report that Irf6 cKO mice present with 1) dysplastic salivary glands due to disruptions of epithelial junctional complexes, likely secondary to elevated activation of RHO GTPases, and 2) increased salivary cell proliferation. These changes result in significantly reduced saliva flow rate and buffering capacity and increased mucus acidity. A marked decrease in expression of CCL27, one of the major mucosal and skin cytokines, was found that correlated with increased bacterial colonization of the oral cavity with the cariogenic pathogen Streptococcus mutans and other bacteria. When placed on a high-sugar diet, Irf6 cKO mice show a 35-fold increase in presentation and severity of dental caries as compared with wild-type control mice. Strikingly, within the 8-wk test period, many molars extensively dissolved, and there was progressive loss of the alveolar bone, likely as a result of increased colonization of periodontal pathogens. These data provide the first mechanistic insight into the heightened caries susceptibility associated with CLP and indicate a direct role for the major CLP gene Irf6 in salivary gland development and a significant role in regulating oral immunity. Our data suggest that careful evaluation of salivary gland function and the implementation of early oral health preventive strategies are warranted to reduce the burden of dental care in this at-risk population.

Background: Variants in the cysteine-rich secretory protein LCCL domain containing 2 gene (CRISPLD2) and in the jumonji, AT-rich interaction domain 2 gene (JARID2) were previously shown to influence non-syndromic oral cleft susceptibility. Herein, we performed a case-control study to examine the potential association of single-nucleotide polymorphisms (SNPs) in CRISPLD2 and JARID2 with non-syndromic cleft lip and/or palate (NSCL/P) in the Brazilian population. Given the ethnicity-dependent genetic predisposition to NSCL/P, we performed a structured analysis taking into account the genomic ancestry variation of each individual., Methods: Four SNPs in CRISPLD2 (rs1546124, rs8061351, rs2326398, and rs4783099) and four in JARID2 (rs915344, rs2299043, rs2237138, and rs2076056), that were previously reported to be associated with NSCL/P, were genotyped in 785 Brazilian patients with NSCL/P (549 with cleft lip with or without cleft palate-NSCL ± P, and 236 with cleft palate only-NSCPO) and 693 unaffected Brazilian controls. Genomic ancestry was assessed with a set of 40 biallelic short insertion/deletion variants previously validated as ancestry informative markers of the Brazilian population., Results: After adjustment of ancestry variations, allelic analysis revealed marginal associations between the CRISPLD2 rs4783099 T allele and increased risk for NSCPO (OR: 1.31, 95% CI: 1.05-1.62, P = 0.01) and between JARID2 rs2237138 and decreased NSCL ± P risk (OR: 0.80, 95% CI: 0.67-0.97, P = 0.02). Haplotype analysis indicated a lack of association between JARID2 haplotypes and non-syndromic oral cleft risk., Conclusions: Our results suggest that CRISPLD2 rs4783099 may represent a risk factor for NSCPO while JARID2 rs2237138 shows a protective effect against NSCL ± P in the Brazilian population., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Common variants in interferon regulatory factor 6 ( IRF6) have been associated with nonsyndromic cleft lip with or without cleft palate (NSCL/P) as well as with tooth agenesis (TA). These variants contribute a small risk towards the 2 congenital conditions and explain only a small percentage of heritability. On the other hand, many IRF6 mutations are known to be a monogenic cause of disease for syndromic orofacial clefting (OFC). We hypothesize that IRF6 mutations in some rare instances could also cause nonsyndromic OFC. To find novel rare variants in IRF6 responsible for nonsyndromic OFC and TA, we performed targeted multiplex sequencing using molecular inversion probes (MIPs) in 1,072 OFC patients, 67 TA patients, and 706 controls. We identified 3 potentially pathogenic de novo mutations in OFC patients. In addition, 3 rare missense variants were identified, for which pathogenicity could not unequivocally be shown, as all variants were either inherited from an unaffected parent or the parental DNA was not available. Retrospective investigation of the patients with these variants revealed the presence of lip pits in one of the patients with a de novo mutation suggesting a Van der Woude syndrome (VWS) phenotype, whereas, in other patients, no lip pits were identified.

Clefting of the lip, with or without palatal involvement (CLP), is associated with a higher incidence of developmental tooth abnormalities, including hypodontia and supernumerary teeth, aberrant crown and root morphologies, and enamel defects, although the underlying mechanistic link is poorly understood. As most CLP genes are expressed throughout the oral epithelium, the authors hypothesized that the expression of CLP genes may persist in the dental epithelium and thus, in addition to their earlier role in labiopalatine development, may play an important functional role in subsequent tooth patterning and amelogenesis. To address this, the authors generated a unique conditional knockout model involving the major CLP gene, Irf6, that overcomes the previously reported perinatal lethality to enable assessment of any posteruption dental phenotypes. A dental epithelium-specific Irf6 conditional knockout (Irf6-cKO) mouse was generated via a Pitx2-Cre driver line. Dental development was analyzed by microcomputed tomography, scanning electron microscopy, histology, immunohistochemistry, and quantitative polymerase chain reaction. Irf6-cKO mice displayed variable hypodontia, occasional supernumerary incisors and molars, as well as crown and root patterning anomalies, including peg-shaped first molars and taurodontic and C-shaped mandibular second molars. Enamel density was reduced in preeruption Irf6-cKO mice, and some shearing of enamel rods was noted in posteruption incisors. There was also rapid attrition of Irf6-cKO molars following eruption. Histologically, Irf6-cKO ameloblasts exhibited disturbances in adhesion and polarity, and delayed enamel formation was confirmed immunohistochemically. Altered structure of Hertwig's epithelial root sheath was also observed. These data support a role for IRF6 in tooth number, crown and root morphology and amelogenesis that is likely due to a functional role of Irf6 in organization and polarity of epithelial cell types. This data reinforce the notion that various isolated tooth defects could be considered part of the CLP spectrum in relatives of an affected individual., Competing Interests: The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article., (© International & American Associations for Dental Research 2016.)

Patients with Van der Woude syndrome typically present with cleft lip, cleft lip and palate, or with cleft palate only. In contrast to non-syndromic cleft lip and/or palate, Van der Woude syndrome typically is characterized by bilateral, paramedian lower-lip pits. Popliteal pterygium syndrome shares features with Van der Woude syndrome, but, in addition, is characterized by a popliteal pterygium, genital anomalies, cutaneous syndactyly of the fingers and the toes, and a characteristic pyramidal fold of skin overlying the nail of the hallux. In some patients oral synechiae or eyelid synechiae are present. Van der Woude Syndrome and Popliteal pterygium syndrome are autosomal dominantly inherited disorders caused by heterozygous mutations in IRF6. We present a three generation family with tremendous intrafamilial phenotypic variability. The newborn index patient had a diagnosis of Popliteal pterygium syndrome. The mother presented with a classic Van der Woude Syndrome, while the maternal grandfather had Van der Woude Syndrome as well as minor signs of Popliteal pterygium syndrome. In all three affecteds the known pathogenic mutation c.265A>G, p.Lys89Glu in IRF6 was identified. While inter- as well as intra-familial variability has been described in IRF6-related disorders, the occurrence of a typical Van der Woude Syndrome without any other anomalies as well as a diagnosis of Popliteal pterygium syndrome in the same family is rare. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background: We conducted a systematic review and meta-analysis of interferon regulatory factor 6 and 8q24 polymorphisms with nonsyndromic cleft lip with/without cleft palate (NSCL/P)., Methods: Data extraction was independently performed by two reviewers. Genotypic effects of four polymorphisms from 31 studies were pooled separately by ethnicity using a mixed-effect logit model with accounting for heterogeneity., Results: For rs2235371, AA and GA carried, respectively, 51% (95% confidence interval [CI], 37%-61%) and 42% (95% CI, 32%-50%) lower risks of NSCL/P than GG genotypes in Asians, but these genotypes were not significant in Caucasians. For rs2013162, only AA was significant, that is, carried 0.65 (95% CI, 0.52-0.82) times lower odds than CC in Caucasians but not for Asians. For rs642961, AA and GA genotypes, respectively, carried 2.47 (95% CI, 1.41-4.35) and 1.40 (95% CI, 1.12-1.75) times higher odds in Asian, and 2.03 (95% CI, 1.52-2.71) and 1.58 (95% CI, 1.37-1.82) times higher odds in Caucasians compare with GG genotypes. For rs987525, AA and CA genotypes carried 2.27 (95% CI, 1.43-3.60) and 1.34 (95% CI, 1.02-1.77) times higher odds in Asian, and 5.25 (95% CI, 3.98-6.91) and 2.13 (95% CI-1.82, 2.49) times higher odds in Caucasians, and 1.42 (95% CI, 1.10-1.82) and 1.28 (95% CI, 1.09-1.50) times higher odds in mixed ethnicities compared with CC genotypes. These variant effects remained significant based on applying Bonferroni corrected-thresholds, except in the mixed ethnicity., Conclusion: We show robust variant effects in NSCL/P. Considering them with other genes and risk factors might be useful to improve prediction of NSCL/P occurrence. Birth Defects Research (Part A) 106:773-788, 2016. © 2016 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc., (© 2016 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.)

Van der Woude syndrome (VWS) is an autosomal dominant malformation syndrome characterized by orofacial clefting (OFC) and lower lip pits. The clinical presentation of VWS is variable and can present as an isolated OFC, making it difficult to distinguish VWS cases from individuals with non-syndromic OFCs. About 70% of causal VWS mutations occur in IRF6, a gene that is also associated with non-syndromic OFCs. Screening for IRF6 mutations in apparently non-syndromic cases has been performed in several modestly sized cohorts with mixed results. In this study, we screened 1521 trios with presumed non-syndromic OFCs to determine the frequency of causal IRF6 mutations. We identified seven likely causal IRF6 mutations, although a posteriori review identified two misdiagnosed VWS families based on the presence of lip pits. We found no evidence for association between rare IRF6 polymorphisms and non-syndromic OFCs. We combined our results with other similar studies (totaling 2472 families) and conclude that causal IRF6 mutations are found in 0.24-0.44% of apparently non-syndromic OFC families. We suggest that clinical mutation screening for IRF6 be considered for certain family patterns such as families with mixed types of OFCs and/or autosomal dominant transmission., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

In a retrospective review of patients seen at the University of Alabama at Birmingham Cleft and Craniofacial Center, four patients with rare interrupted clefting were identified who had undergone genetic testing. Each of these patients had a typical cleft lip, with intact hard palate and cleft of the soft palate. Given this picture of mixed clefting, IRF6 sequencing was done and was negative for mutations in all four patients. As genetic testing for single-gene mutations and exome sequencing become clinically available, it may be possible to identify novel mutations responsible for this previously unreported type of interrupted clefting.

Objectives: We investigated the association between non-syndromic oral cleft and variants in IRF6 (rs2235371 and rs642961) and 8q24 region (rs987525) according to the ancestry contribution of the Brazilian population., Subjects and Methods: Subjects with oral cleft (CL, CLP, or CP) and their parents were selected from different geographic regions of Brazil. Polymorphisms were genotyped using a TaqMan assay and genomic ancestry was estimated using a panel of 48 INDEL polymorphisms., Results: A total of 259 probands were analyzed. A TDT detected overtransmission of the rs2235371 G allele (P = 0.0008) in the total sample. A significant association of this allele was also observed in CLP (P = 0.0343) and CLP + CL (P = 0.0027). IRF6 haplotype analysis showed that the G/A haplotype increased the risk for cleft in children (single dose: P = 0.0038, double dose: P = 0.0022) and in mothers (single dose: P = 0.0016). The rs987525 (8q24) also exhibited an association between the A allele and the CLP + CL group (P = 0.0462). These results were confirmed in the probands with European ancestry., Conclusions: The 8q24 region plays a role in CL/P and the IRF6 G/A haplotype (rs2235371/rs642961) increases the risk for oral cleft in the Brazilian population., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)