A comprehensive consolidation of data on the relationship between IRF6 polymorphisms and non-syndromic cleft lip/palate susceptibility: From 79 case-control studies.

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.

A Complex Intrachromosomal Rearrangement Disrupting IRF6 in a Family with Popliteal Pterygium and Van der Woude Syndromes.

Clefts of the lip and/or palate (CL/P) are considered the most common form of congenital anomalies occurring either in isolation or in association with other clinical features. Van der woude syndrome (VWS) is associated with about 2% of all CL/P cases and is further characterized by having lower lip pits. Popliteal pterygium syndrome (PPS) is a more severe form of VWS, normally characterized by orofacial clefts, lower lip pits, skin webbing, skeletal anomalies and syndactyly of toes and fingers. Both syndromes are inherited in an autosomal dominant manner, usually caused by heterozygous mutations in the Interferon Regulatory Factor 6 (IRF6) gene. Here we report the case of a two-generation family where the index presented with popliteal pterygium syndrome while both the father and sister had clinical features of van der woude syndrome, but without any point mutations detected by re-sequencing of known gene panels or microarray testing. Using whole genome sequencing (WGS) followed by local de novo assembly, we discover and validate a copy-neutral, 429 kb complex intra-chromosomal rearrangement in the long arm of chromosome 1, disrupting the IRF6 gene. This variant is copy-neutral, novel against publicly available databases, and segregates in the family in an autosomal dominant pattern. This finding suggests that missing heritability in rare diseases may be due to complex genomic rearrangements that can be resolved by WGS and de novo assembly, helping deliver answers to patients where no genetic etiology was identified by other means.

Popliteal Pterygium With Van Der Woude Syndrome.

Van der Woude syndrome (VWS) is an autosomal dominant syndrome due to mutation of a gene located in the long arm of chromosome 1 (1q32.3-q4) called the interferon regulatory factor-6 (IRF6) gene. VW syndrome-affected children are born with a cleft lip or palate, hypodontia (absent teeth), and bilateral paramedian lower-lip pits, which are usually moist because they are often associated with accessory salivary glands and mucous glands that empty into the pits. Popliteal pterygium syndrome (PPS), also known as a fasciogenito-popliteal syndrome or popliteal web syndrome is a rare autosomal dominant disorder with an incidence of approximately 1 in 300,000 live births. The most common clinical manifestations are popliteal webbing, cleft palate, cleft lip, syndactyly, and genital and nail anomalies. This report describes the clinical features in one case with positive family history, showing the range of anomalies found in popliteal pterygium with VWS.

Novel rare variations in IRF6 in subjects with non-syndromic cleft lip and palate and dental agenesis.

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.

Association of long interspersed nucleotide element-1 and interferon regulatory factor 6 methylation changes with nonsyndromic cleft lip with or without cleft palate.

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.

Association of single-nucleotide polymorphisms in the IRF6 gene with non-syndromic cleft lip with or without cleft palate in the Xinjiang Uyghur population.

Our main aim was to investigate the association between the interferon regulatory factor (IRF6) gene and non-syndromic cleft lip and palate (nsCLP) in the Xinjiang Uyghur population. Twelve single nucleotide polymorphisms (SNP) were screened in a group of 100 patients with nsCLP and in a control group of 60 unaffected subjects by next generation sequencing using a MiSeq Benchtop Sequencer (Illumina). Our case-control association analysis showed that the SNP marker rs7545538 differed significantly in genotype (codominant model; CC compared with CG compared with GG; p=0.038) and allele frequencies (odds ratio (OR)=1.89, 95% CI 1.18-3.03, p=0.007) between patients with nsCLP and controls. Analysis of the recessive model of inheritance showed that distribution of the recessive model of rs7545538 (GG compared with CC+GC) was significantly higher in patients with nsCLP than in controls (OR=2.5, 95% CI 1.13-5.37, p=0.021) and had a borderline association with an increased risk of nsCLP (OR=2.5, 95% CI 1.13-5.37, p=0.021). Markers rs2235377 and rs2235371 also differed significantly in dominant and over-dominant models of inheritance (p=0.037) while increased G allele frequency was seen in SNP rs2235373 (p=0.03). A haplotype analysis showed four common haplotypes in Block 1: CCGGT>CCGAT>CACAT>TAGAC (in frequency). The 5-marker combination haplotype CCGAT was significantly more common in patients with nsCLP than in controls (p=0.032). In Block 2, the overall distribution of the haplotypes TAC and TAG predicted by the three SNP differed significantly between the patients with nsCLP and control subjects (p=0.009 and 0.003, respectively). Our results showed that genetic polymorphism of the IRF6 gene is associated with increased risk of nsCLP in a Xinjiang Uyghur population.

De novo 2.3 Mb microdeletion of 1q32.2 involving the Van der Woude Syndrome locus.

BACKGROUND: Van der Woude syndrome is the most common among syndromes which include cleft lip and/or cleft palate as one of the presentations. It is usually caused by mutations in the interferon regulatory factor 6 (IRF6) gene. CASE PRESENTATION: We previously reported on a patient with suspected deletion of the IRF6 gene. Using the Affymetrix Human SNP 6.0 Array, the interstitial deletion has been confirmed and found to be approximately 2.327-2.334 Mb within the 1q32.2 region. Although several known genes were deleted, the patient has no other phenotype apart from the orofacial presentations typical of VWS. The same deletion was not present in either parent and his two siblings were also phenotypically normal. CONCLUSIONS: Other than IRF6, the genes which are deleted in this patient appear to be insensitive to copy number and haploinsufficiency. We compared the deletion in this patient with another case which was also mapped by high resolution array but had additional phenotypic features.