Association of MSX1 and TGFB3 with nonsyndromic clefting in humans

The ectodermal loss of ARHGAP29 alters epithelial morphology and organization and disrupts murine palatal development

Orofacial clefts, including cleft palate (CP), are among the most common types of birth defects. CP specifically, results from a failure of palatal shelf fusion during development. Previous studies have shown that mutations in RhoA GTPase Activating Protein 29 ( ARHGAP29) are linked to CP, yet the role and tissue-specific requirements for ARHGAP29 during palatogenesis remain unknown. Here, we use tissue-specific deletion of Arhgap29 in mice to provide the first direct evidence that ARHGAP29 is essential for proper palatal elevation and fusion. We demonstrate that ectodermal conditional loss of Arhgap29 induces a significant delay in the fusion of palatal shelves at embryonic (E) day 14.5 and an incomplete yet significantly penetrant cleft palate at E18.5 - neither of which are observed when Arhgap29 is lost later in development using K14-Cre. Phenotypic analyses of palatal shelves at E14.5 reveal a disorganized and thicker epithelium at the tip of the shelves. Loss of Arhgap29 increases palate epithelial cell area and upregulates alpha-smooth muscle actin and phospho-myosin regulatory light chain implicating cell morphology and contractility as drivers of CP.

Summary statement

This study in mice is the first direct evidence that ARHGAP29 is essential for proper palatal elevation and fusion. Loss of Arhgap29 alters oral epithelial morphology and upregulates contractility proteins.

foxe1 mutant zebrafish show indications of a hypothyroid phenotype and increased sensitivity to ethanol for craniofacial malformations

BACKGROUND

FOXE1 mutations in humans are associated with cleft palate and hypothyroidism. We previously developed a foxe1 mutant zebrafish demonstrating mineralization defects in larvae. In the present study, we investigate the thyroid status and skeletal phenotype of adult foxe1 mutants.

RESULTS

Mutant fish have increased expression of tshβ in the pituitary, and of hepatic dio1 and dio2. In plasma, we found higher Mg levels. Together these findings are indicative of hypothyroidism. We further observed mineralization defects in scales due to enhanced osteoclast activity as measured by increased expression levels of tracp, ctsk, and rankl. Gene-environment interactions in the etiology of FOXE1-related craniofacial abnormalities remain elusive, which prompts the need for models to investigate genotype-phenotype associations. We here investigated whether ethanol exposure increases the risk of developing craniofacial malformations in foxe1 mutant larvae that we compared to wild types. We found in ethanol-exposed mutants an increased incidence of developmental malformations and marked changes in gene expression patterns of cartilage markers (sox9a), apoptotic markers (casp3b), retinoic acid metabolism (cyp26c1), and tissue hypoxia markers (hifaa, hifab).

CONCLUSION

Taken together, this study shows that the foxe1 mutant zebrafish recapitulates phenotypes associated with FOXE1 mutations in human patients and a clear foxe1-ethanol interaction.

Multi-ancestry Genome Wide Association Study Meta-analysis of Non-syndromic Orofacial Clefts

Non-syndromic orofacial clefts (NSOC) are common craniofacial birth defects, and result from both genetic and environmental factors. NSOC include three major sub-phenotypes: non-syndromic cleft lip with palate (NSCLP), non-syndromic cleft lip only (NSCLO) and non-syndromic cleft palate only (NSCPO), NSCLP and NSCLO are also sometimes grouped as non-syndromic cleft lip with or without cleft palate (NSCL/P) based on epidemiology. Currently known loci only explain a limited proportion of the heritability of NSOC. Further, differences in genetic susceptibility among the sub-phenotypes are poorly characterized. We performed a multi-ancestry GWAS meta-analysis on 44,094 individuals (9,381 cases, 28,510 controls, 2042 case-parent trios and 18 multiplex pedigrees) of East Asian, European, Latin and South American, and African ancestry for both NSOC and subtypes. We identified 50 loci, including 11 novel loci: four loci ( CALD1 , SHH , NRG1 and LINC00320 ) associated with both NSOC and NSCL/P, two loci ( NTRK1 and RUNX1 ) only associated with NSOC, four loci ( HMGCR , PRICKLE1 , SOX9 and MYH9 ) only associated with NSCL/P and one locus ( ALX1 ) specifically associated with NSCLO. Five of the novel loci are located in regions containing genes associated with syndromic orofacial clefts ( SHH , NTRK1, CALD1, ALX1 and SOX9 ); seven of the novel loci are located in regions containing genes-implicated in craniofacial development ( HMGCR, SHH, PRICKLE1, ALX1, SOX9, RUNX1, MYH9 ). Genetic correlation and colocalization analyses revealed an overlap between signals associated with NSCLO, NSCPO and NSCLP, but there were also notable differences, emphasizing the complexity of common and distinct genetic processes affecting lip and palate development.

Characteristic craniofacial defects associated with a novel USP9X truncation mutation

Germline loss-of-function mutations in USP9X have been reported to cause a wide spectrum of congenital anomalies. Here, we report a Japanese girl with a novel heterozygous nonsense mutation in USP9X who exhibited intellectual disability with characteristic craniofacial abnormalities, including hypotelorism, brachycephaly, hypodontia, micrognathia, severe dental crowding, and an isolated submucous cleft palate. Our findings provide further evidence that disruptions in USP9X contribute to a broad range of congenital craniofacial abnormalities.

Transforming growth factor beta signaling and craniofacial development: modeling human diseases in zebrafish

Humans and other jawed vertebrates rely heavily on their craniofacial skeleton for eating, breathing, and communicating. As such, it is vital that the elements of the craniofacial skeleton develop properly during embryogenesis to ensure a high quality of life and evolutionary fitness. Indeed, craniofacial abnormalities, including cleft palate and craniosynostosis, represent some of the most common congenital abnormalities in newborns. Like many other organ systems, the development of the craniofacial skeleton is complex, relying on specification and migration of the neural crest, patterning of the pharyngeal arches, and morphogenesis of each skeletal element into its final form. These processes must be carefully coordinated and integrated. One way this is achieved is through the spatial and temporal deployment of cell signaling pathways. Recent studies conducted using the zebrafish model underscore the importance of the Transforming Growth Factor Beta (TGF-β) and Bone Morphogenetic Protein (BMP) pathways in craniofacial development. Although both pathways contain similar components, each pathway results in unique outcomes on a cellular level. In this review, we will cover studies conducted using zebrafish that show the necessity of these pathways in each stage of craniofacial development, starting with the induction of the neural crest, and ending with the morphogenesis of craniofacial elements. We will also cover human skeletal and craniofacial diseases and malformations caused by mutations in the components of these pathways (e.g., cleft palate, craniosynostosis, etc.) and the potential utility of zebrafish in studying the etiology of these diseases. We will also briefly cover the utility of the zebrafish model in joint development and biology and discuss the role of TGF-β/BMP signaling in these processes and the diseases that result from aberrancies in these pathways, including osteoarthritis and multiple synostoses syndrome. Overall, this review will demonstrate the critical roles of TGF-β/BMP signaling in craniofacial development and show the utility of the zebrafish model in development and disease.

Periderm Fate during Palatogenesis: TGF-β and Periderm Dedifferentiation

Failure of palatogenesis results in cleft palate, one of the most common congenital disabilities in humans. During the final phases of palatogenesis, the protective function of the peridermal cell layer must be eliminated for the medial edge epithelia to adhere properly, which is a prerequisite for the successful fusion of the secondary palate. However, a deeper understanding of the role and fate of the periderm in palatal adherence and fusion has been hampered due to a lack of appropriate periderm-specific genetic tools to examine this cell type in vivo. Here we used the cytokeratin-6A (Krt-6a) locus to develop both constitutive (Krt6ai-Cre) and inducible (Krt6ai-CreERT2) periderm-specific Cre driver mouse lines. These novel lines allowed us to achieve both the spatial and temporal control needed to dissect the periderm fate on a cellular resolution during palatogenesis. Our studies suggest that, already before the opposing palatal shelves contact each other, at least some palatal periderm cells start to gradually lose their squamous periderm-like phenotype and dedifferentiate into cuboidal cells, reminiscent of the basal epithelial cells seen in the palatal midline seam. Moreover, we show that transforming growth factor-β (TGF-β) signaling plays a critical periderm-specific role in palatogenesis. Thirty-three percent of embryos lacking a gene encoding the TGF-β type I receptor (Tgfbr1) in the periderm display a complete cleft of the secondary palate. Our subsequent experiments demonstrated that Tgfbr1-deficient periderm fails to undergo appropriate dedifferentiation. These studies define the periderm cell fate during palatogenesis and reveal a novel, critical role for TGF-β signaling in periderm dedifferentiation, which is a prerequisite for appropriate palatal epithelial adhesion and fusion.

Genetic and epigenetic studies in non-syndromic oral clefts

The etiology of non-syndromic oral clefts (NSOFC) is complex with genetics, genomics, epigenetics, and stochastics factors playing a role. Several approaches have been applied to understand the etiology of non-syndromic oral clefts. These include linkage, candidate gene association studies, genome-wide association studies, whole-genome sequencing, copy number variations, and epigenetics. In this review, we shared these approaches, genes, and loci reported in some studies.

Genetic markers for non-syndromic orofacial clefts in populations of European ancestry: a meta-analysis

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.

Ras signaling and its effector RREB1 are required for the dissociation of MEE cells in palatogenesis

Cleft palate is one of the major congenital craniofacial birth defects. The etiology underlying the pathogenesis of cleft palate has yet to be fully elucidated. Dissociation of the medial edge epithelium (MEE) at the contacting region of palatal shelves and subsequent migration or apoptosis of MEE cells is required for proper MEE removal. Ras-responsive element-binding protein 1 (RREB1), a RAS transcriptional effector, has recently been shown to play a crucial role in developmental epithelial–mesenchymal transition (EMT), in which loss of epithelial characteristics is an initial step, during mid-gastrulation of embryonic development. Interestingly, the involvement of RREB1 in cleft palate has been indicated in humans. Here, we demonstrated that pan-Ras inhibitor prevents the dissociation of MEE during murine palatal fusion. Rreb1 is expressed in the palatal epithelium during palatal fusion, and knockdown of Rreb1 in palatal organ culture resulted in palatal fusion defects by inhibiting the dissociation of MEE cells. Our present findings provide evidence that RREB1-mediated Ras signaling is required during palatal fusion. Aberrant RREB1-mediated Ras signaling might be involved in the pathogenesis of cleft palate.

Summary: RREB1, a known transcriptional factor that acts downstream of Ras signaling, is expressed in the medial edge epithelium (MEE) region and required for the dissociation of MEE during palatal fusion.

Orofacial clefts embryology, classification, epidemiology, and genetics

Orofacial clefts (OFCs) rank as the second most common congenital birth defect in the United States after Down syndrome and are the most common head and neck congenital malformations. They are classified as cleft lip with or without cleft palate (CL/P) and cleft palate only (CPO). OFCs have significant psychological and socio-economic impact on patients and their families and require a multidisciplinary approach for management and counseling. A complex interaction between genetic and environmental factors contributes to the incidence and clinical presentation of OFCs. In this comprehensive review, the embryology, classification, epidemiology and etiology of clefts are thoroughly discussed and a "state-of-the-art" snapshot of the recent advances in the genetics of OFCs is presented.

Genetics and signaling mechanisms of orofacial clefts

Craniofacial development involves several complex tissue movements including several fusion processes to form the frontonasal and maxillary structures, including the upper lip and palate. Each of these movements are controlled by many different factors that are tightly regulated by several integral morphogenetic signaling pathways. Subject to both genetic and environmental influences, interruption at nearly any stage can disrupt lip, nasal, or palate fusion and result in a cleft. Here, we discuss many of the genetic risk factors that may contribute to the presentation of orofacial clefts in patients, and several of the key signaling pathways and underlying cellular mechanisms that control lip and palate formation, as identified primarily through investigating equivalent processes in animal models, are examined.

Non-syndromic Cleft Palate: An Overview on Human Genetic and Environmental Risk Factors

The epithelial and mesenchymal cells involved in early embryonic facial development are guided by complex regulatory mechanisms. Any factor perturbing the growth, approach and fusion of the frontonasal and maxillary processes could result in orofacial clefts that represent the most common craniofacial malformations in humans. The rarest and, probably for this reason, the least studied form of cleft involves only the secondary palate, which is posterior to the incisive foramen. The etiology of cleft palate only is multifactorial and involves both genetic and environmental risk factors. The intention of this review is to give the reader an overview of the efforts made by researchers to shed light on the underlying causes of this birth defect. Most of the scientific papers suggesting potential environmental and genetic causes of non-syndromic cleft palate are summarized in this review, including genome-wide association and gene–environment interaction studies.

Ankyloglossia Superior Syndrome With Complex Craniofacial Anomalies: Case Report and Literature Review

Ankyloglossia superior syndrome is an extremely rare entity in which centrally located glossopalatine ankylosis is a principal feature. Some cases are accompanied by cleft palate, micrognathia, or tongue hypoplasia, and affected patients need careful nutritional and respiratory support. We describe a newborn girl in whom ankyloglossia superior syndrome comprised complex craniofacial malformations, including cleft palate, micrognathia, microglossia, and natal teeth as well as limb anomalies. Surgical treatment entailed release of synechiae, and glossopexy was performed successfully to prevent postsurgical airway complications and to ensure adequate nutrition by nipple feeding during infancy.

Transcriptional analysis of cleft palate in TGFβ3 mutant mice

Cleft palate (CP) is one of the most common craniofacial birth defects, impacting about 1 in 800 births in the USA. Tgf-β3 plays a critical role in regulating murine palate development, and Tgf-β3 null mutants develop cleft palate with 100% penetrance. In this study, we compared global palatal transcriptomes of wild type (WT) and Tgf-β3 −/− homozygous (HM) mouse embryos at the crucial palatogenesis stages of E14.5, and E16.5, using RNA-seq data. We found 1,809 and 2,127 differentially expressed genes at E16.5 vs. E14.5 in the WT and HM groups, respectively (adjusted p < 0.05; |fold change|> 2.0). We focused on the genes that were uniquely up/downregulated in WT or HM at E16.5 vs. E14.5 to identify genes associated with CP. Systems biology analysis relating to cell behaviors and function of WT and HM specific genes identified functional non-Smad pathways and preference of apoptosis to epithelial-mesenchymal transition. We identified 24 HM specific and 11 WT specific genes that are CP-related and/or involved in Tgf-β3 signaling. We validated the expression of 29 of the 35 genes using qRT-PCR and the trend of mRNA expression is similar to that of RNA-seq data . Our results enrich our understanding of genes associated with CP that are directly or indirectly regulated via TGF-β.

Msx1 deficiency interacts with hypoxia and induces a morphogenetic regulation during mouse lip development

Nonsyndromic clefts of the lip and palate are common birth defects resulting from gene-gene and gene-environment interactions. Mutations in human MSX1 have been linked to orofacial clefting and we show here that Msx1 deficiency causes a growth defect of the medial nasal process (Mnp) in mouse embryos. Although this defect alone does not disrupt lip formation, Msx1-deficient embryos develop a cleft lip when the mother is transiently exposed to reduced oxygen levels or to phenytoin, a drug known to cause embryonic hypoxia. In the absence of interacting environmental factors, the Mnp growth defect caused by Msx1 deficiency is modified by a Pax9-dependent 'morphogenetic regulation', which modulates Mnp shape, rescues lip formation and involves a localized abrogation of Bmp4-mediated repression of Pax9 Analyses of GWAS data revealed a genome-wide significant association of a Gene Ontology morphogenesis term (including assigned roles for MSX1, MSX2, PAX9, BMP4 and GREM1) specifically for nonsyndromic cleft lip with cleft palate. Our data indicate that MSX1 mutations could increase the risk for cleft lip formation by interacting with an impaired morphogenetic regulation that adjusts Mnp shape, or through interactions that inhibit Mnp growth.

Association of MAPK4 and SOX1-OT gene polymorphisms with cleft lip palate in multiplex families: A genetic study

Background. Cleft lip and palate (CLP) is a common congenital anomaly. Many genes, like MAPK4 and SOX-1OT, are associated with its etiology in different populations. High-risk markers on these gene sreported in other populations were not studied in our population. Hence, the study aimed to determine the association of MAPK4 and SOX-1OT polymorphisms in CLP in multiplex families.

Methods. Based on inclusion and exclusion criteria, we selected 20 multiplex CLP families for this case‒control study, in which the affected individuals and healthy controls selected from these families were compared. Fifty subjects affected with cleft and 38 unaffected subjects were included in the study. The polymorphisms studied for the association consisted of rs726455 and rs2969972 in the genes SOX-1 OT and MAPK4, respectively. DNA was isolated and sent for genotyping using the MassArray method. Plink, a whole-genome association analysis toolset, was used for statistical analysis.

Results. Both polymorphisms followed Hardy–Weinberg equilibrium. The rs726455 of SOX-1OT yielded a P-value of 0.983 and an allelic odds ratio (OR) of 0.983. For rs2969972 of MAPK4, the P-value was 0.04 (significant), and the allelic OR was 0.51. Minor allele frequency (MAF) in the unaffected subjects was more than the MAF in the affected subjects for rs2969972.

Conclusion. The results suggested that polymorphism rs726455 on SOX-1OT was not associated with familial cases of CLP. Since MAF in the unaffected subjects was more than the MAF-affected subjects, rs2969972 on MAPK4 is protective in the multiplex families.

[Cleft lip and palate]

BACKGROUND

Cleft lip and palate (CLP) represents a group of malformations of unknown etiology but similar phenotypes. This implies consequences for the diagnostics, therapy, prevention, prognosis and risk estimation.

OBJECTIVE

Definition of CLP subtypes and the embryonic development, clarification of correlations and differences between entities using epidemiological data, overview of the present state of genetic analyses, correlation to syndromes, sequences and associations and resulting consequences for clinical practice.

MATERIAL AND METHODS

Update on embryological development of the face, summary of epidemiological and genetic studies and considerations on pedopathological and forensic aspects.

RESULTS

Syndromic and non-syndromic CLP exhibit different and highly variable etiologies, therapeutic needs and prognosis. A thorough understanding is mandatory to distinguish between the different subgroups. In addition to specific aspects of CLP for the pediatric (forensic) pathologist this article provides an overall view of the topic which aims to help understand these malformations.

TGFβ3, MSX1, and MMP3 as Candidates for NSCL±P in an Indian Population

OBJECTIVE

To evaluate the association of transforming growth factor β3 ( TGFβ3), muscle segment homeobox 1 ( MSX1), Metalloproteinases 3 ( MMP3), and MMP9 genes as candidates for nonsyndromic cleft lip and/or palate in an Indian population.

DESIGN

Case-control association study, mutational screening, and functional evaluation of obtained mutations.

SETTING

Mutational screening of the developmental genes, TGFβ3 and MSX1, along with functional evaluation and association of promoter region SNPs-one each in MMP3 and MMP9.

PATIENTS, PARTICIPANTS

Two hundred forty five NSCL±P cases from G. S. Memorial Plastic Surgery Hospital and Trauma Center, Varanasi and 201 healthy controls without a family history of congenital malformations from nearby schools, primary health centers, and the university hospital.

MAIN OUTCOME MEASURE(S)

Sequencing, SSCP, and PCR-RFLP were used for candidate gene screening. MatInspector and electrophoretic mobility shift assay (EMSA) were used to check the differential transcription factor binding of the variants at promoter region. Luciferase assay was used to test the transcriptional potential of the variant, and evaluation of the alternative splice site was carried out using exon-trapping experiment.

RESULTS

Metalloproteinases3 -1171 5A/6A was associated with NSCL±P, whereas MMP9 -1562 C/T did not show association. A rare variant in the promoter region of TGFβ3 (rs117462711) creates a differential binding site, confirmed by EMSA. Luciferase assay showed 3.7-fold increased expression level in mutant construct. A synonymous change in MSX1 (rs34165410) showed association with NSCL±P, which may create an alternative splice site or lead to low codon usage. Exon-trapping experiment failed to confirm alternative splicing, indicating low codon usage frequency of the mutant affecting the gene function.

CONCLUSIONS

TGFβ3, MSX1, and MMP3 are candidates for NSCL±P.

Secondary Dentition Characteristics in Children With Nonsyndromic Unilateral Cleft Lip and Palate

Objective:

Children with cleft lip and palate are reported to be commonly associated with higher prevalence of dental anomalies such as hypodontia, supernumeraries, and abnormalities in tooth size, shape, and position. This study investigated the prevalence of dental anomalies in a longitudinal cohort of children with unilateral cleft lip and palate (UCLP).

Design:

The study was a retrospective analysis of radiographs, study models, and treatment notes.

Patients:

Sixty patients with repaired UCLP aged 13 years old with complete dental records dating from 5 years of age were included.

Methods:

Study casts, dental panoramic, anterior maxillary occlusal, and periapical radiographs of the patients were examined for cleft-sidedness, congenitally missing permanent teeth, supernumerary teeth, microdontic, and macrodontic teeth in the anterior maxillary region, presence of malformed permanent cleft-sided lateral incisor and its morphology (peg-shaped, conical shaped, canine-formed), positions of the permanent lateral incisors relative to the cleft side and presence of rotated cleft-sided central incisors.

Results:

Of the 60 patients studied, 63.3% had hypodontia, 21.7% had supernumerary teeth, 69.6% had microdontia, and 12.5% had macrodontia. All of the cleft-sided permanent lateral incisors had associated anomalies, with a large proportion (43.1%) missing; and when present in 31 subjects, the majority (90.3%) was positioned distal to the cleft. Most of the cleft-sided permanent central incisors were rotated if present, and prevalent at 86.7%.

Conclusion:

A high prevalence of dental anomalies was observed in this sample of children with UCLP.

Interaction Effect of RsaI and BamHI Polymorphisms of TGFα, BMP2 and BMP4 on the Occurrence of Non-Syndromic Cleft Lip and Palate in Iranian Patients

BACKGROUND

Orofacial cleft is the most common congenital defect of the maxillofacial region. Its non-syndromic type is multi-factorial, and several genes are involved in its occurrence. This study aimed to assess the interaction effect of Rsal and BamHI polymorphisms of Transforming Growth Factor-alpha (TGFα) gene and Bone Morphogenetic Protein-2 (BMP2) and BMP4 variants on the occurrence of Non-Syndromic Cleft Lip and Palate (NSCLP) in the Iranian population.

METHODS

This case-control study was conducted on 120 children with NSCLP and 215 healthy children. Genotyping of the TGFA/BamHI (rs11466297), TGFA/RsaI (rs37322-48), BMP4 (rs17563) and BMP2 (rs235768) was performed by Polymerase Chain Reaction (PCR) and Restriction Fragment Length Polymorphism (RFLP) methods. Logistic regression was applied to determine the effective factors and the interaction effect of different variants on the occurrence of NSCLP.

RESULTS

Gender of patients had no significant association with the occurrence of NSCLP (p=0.335). Multiple logistic regression showed that the interaction effect of the aforementioned polymorphisms on the occurrence of NSCLP was not statistically significant (p=1.000).

CONCLUSION

Although the individual effect of each of the BMP4, BMP2, RsaI and BamHI variants on the occurrence of NSCLP in the Iranian population has been previously confirmed, their interaction does not play a role in this respect.

Evaluation of Potential Modifiers of the Palatal Phenotype in the 22q11.2 Deletion Syndrome

Objective

To evaluate potential modifiers of the palatal phenotype in individuals with the 22q11.2 deletion syndrome.

Design

Data from 356 subjects enrolled in a study of the 22q11.2 deletion syndrome were used to evaluate potential modifiers of the palatal phenotype. Specifically, subjects with and without velopharyngeal inadequacy and/or structural malformations of the palate were compared with respect to gender, race, and genotype for variants of seven genes that may influence palatal development.

Methods

The chi-square test or Fisher exact test was used to evaluate the association between palatal phenotype and each potential modifier. Odds ratios and their associated 95% confidence intervals were used to measure the magnitude of the association between palatal phenotype, subject gender and race, and each of the bi-allelic variants.

Results

The palatal phenotype observed in individuals with the 22q11.2 deletion syndrome was significantly associated with both gender and race. In addition, there was tentative evidence that the palatal phenotype may be influenced by variation within the gene that encodes methionine synthase.

Conclusions

Variation in the palatal phenotype observed between individuals with the 22q11.2 deletion syndrome may be related to personal characteristics such as gender and race as well as variation within genes that reside outside of the 22q11.2 region.

Oral Clefts, Maternal Smoking, and TGFA: A Meta-Analysis of Gene-Environment Interaction

Objective

A meta-analysis was performed to examine the association among maternal cigarette smoking, infant genotype at the Taq1 site in the transforming growth factor α (TGFA) locus, and risk of nonsyndromic oral clefts, both cleft palate (CP) and cleft lip with or without cleft palate (CL/P).

Design

Five published case-control studies were included in the meta-analyis. Pooled Mantel-Haenszel odds ratios (OR) and 95% confidence intervals (CIs) were computed. Gene-environment interaction was also assessed by using the pooled data in a case-only analysis and polytomous logistic regression.

Results

Among nonsmoking mothers, there was no evidence of any increased risk for CP if the infant carried the TGFA Taq1 C2 allele. If the mother reported smoking, however, there was an overall increased risk for CP if the infant carried the C2 allele (ORsmokers = 1.95; 95% CI = 1.22 to 3.10). TGFA genotype did not increase risk to CL/P, regardless of maternal smoking status. Polytomous logistic regression revealed a significant overall smoking effect for CL/P (OR = 1.64, 95% CI = 1.33 to 2.02) and CP (OR = 1.42, 95% CI = 1.06 to 1.90).

Conclusions

While maternal smoking was a consistent risk factor for both CL/P and CP across all studies, the suggestive evidence for gene-environment interaction between the infant's genotype at the Taq1 marker in TGFA and maternal smoking was limited to CP. Furthermore, evidence for such gene-environment interaction was strongest in a case-control study drawn from a birth defect registry where infants with non-cleft defects served as controls.

Association between 10 Microsatellite Markers and Nonsyndromic Cleft Lip Palate in the Chilean Population

Objective

The objective of this case-control study was to evaluate the possible association between nonsyndromic cleft lip/palate (NSCLP) and 10 genetic markers in four chromosomal regions in the admixed Spanish-Amerindian Chilean population.

Setting

Study participants included 56 patients with NSCLP identified and interviewed for positive family history during the course of clinical examinations at different rehabilitation centers in the cities of Santiago and Talca, Chile. A control group of 59 normal individuals without known familial antecedents of clefting was obtained from blood bank donors of the University Hospital, University of Chile. Cases and controls belonged to low- to low-middle socioeconomic strata.

Results

Ten markers from chromosome 4p, 4q, 6p, 17q, and 19q were assessed (MSX1, D4S175, D4S192, F13A1, EDN1, D6S89, D6S105, D6S109, D17S579, BCL3). Four of them showed significant deviations from Hardy-Weinberg expectations in controls, according to the exact test (D4S192, BCL3, F13A1, and D6S89). The case-control comparison by means of the CLUMP program showed significant differences only in BCL3, and D6S109 almost reached statistical significance.

Conclusions

Most of the genetic regions with positive results in Caucasian populations may not be involved in NSCLP in Chile, regardless of the positive evidence for the candidate region on chromosome 19. Similar findings have been reported recently in the Chinese population.

Linkage Disequilibrium between MSX1 and Non-syndromic Cleft Lip/Palate in the Chilean Population

Non-syndromic cleft lip/palate (NSCLP) is a complex genetic trait. Linkage and association studies have suggested that a clefting locus could be located on chromosome 4p. Sixty Chilean families were recruited for this study; from these, we used unrelated trios to evaluate the possible linkage disequilibrium between MSX1 and NSCLP. An intragenic marker, MSX1-CA, and an extragenic marker, D4S432 at a distance of 0.8 cM from MSX1, were analyzed by means of polymerase chain-reaction with fluorescent-labeled forward primers, followed by electrophoresis on a laser-fluorescent sequencer. We carried out a transmission/disequilibrium test (TDT) for multiple alleles to evaluate the presence of linkage disequilibrium. Results showed a preferential transmission of the 169-bp allele of MSX1 (p = 0.03). Although there was no preferential transmission for the D4S432 marker, the overall extended TDT (ETDT) showed a significant result (p = 0.01). The authors’ findings support the hypothesis of the contribution of MSX1 in the etiology of NSCLP in the Chilean population.

TGF-β Signal Transduction in Oro-facial Health and Non-malignant Disease (Part I)

The transforming growth factor-beta (TGF-β) family of cytokines consists of multi-functional polypeptides that regulate a variety of cell processes, including proliferation, differentiation, apoptosis, extracellular matrix elaboration, angiogenesis, and immune suppression, among others. In so doing, TGF-β plays a key role in the control of cell behavior in both health and disease. In this report, we review what is known about the mechanisms of activation of the peptide, together with details of TGF-β signal transduction pathways. This review summarizes the evidence implicating TGF-β in normal physiological processes of the craniofacial complex—such as palatogenesis, tooth formation, wound healing, and scarring—and then evaluates its role in non-malignant disease processes such as scleroderma, submucous fibrosis, periodontal disease, and lichen planus.

MSX1 gene polymorphisms in Mexican patients with non-syndromic cleft lip/palate

OBJECTIVE

Non-syndromic cleft lip/palate malformation (CL/P) is one of the most common birth defects in humans and has a complex etiology involving genetic and environmental factors. Mutations in the MSX1 gene are critical during craniofacial development. The purpose of this study was to investigate the contribution of MSX1 gene polymorphisms to the risk of developing CL/P in a sample of Mexican patients.

METHODS

The sample consisted of 282 subjects (69 cases and 213 relatives). Four single-nucleotide polymorphisms (SNP1, P147Q, SNP5 and P278S) were tested for association with CL/P in triad and case-pseudo-control analyses. Polymorphism typing was performed by restriction fragment length polymorphism and dot-blot techniques. Allele and genotype frequencies were calculated between patients and pseudo-controls and compared using the Chi square test with Yates correction. Odds ratios and 95% confidence intervals were obtained using SPSS software (v19). Triad analysis was also performed using the program HAPLIN (v5.3).

RESULTS

In the cases and pseudo-controls, an association was found between CL/P and the SNP1-G allele (P = 0.031) and the SNP1-G/G genotype (P = 0.032), a polymorphism located near MSX1. Triad analysis showed a tendency toward CL/P susceptibility for the genotype SNP1-G/G (P = 0.075) and an association between CL/P and the haplotype GCTC (P = 0.037). No associated haplotype was found in the cases and pseudo-controls. Two partial haplotypes, GT (SNP1-SNP5) (P = 0.032) and GC (SNP1-P278S) (P = 0.033), were associated with susceptibility in the heterozygous and homozygous types, respectively. In contrast, haplotype AT (SNP1-SNP5) was associated with protection (P = 0.012) in the homozygous type.

CONCLUSIONS

The results of this study suggest an association between CL/P susceptibility and SNP1, located near the MSX1 gene, in the Mexican population.

Maternal active smoking and risk of oral clefts: a meta-analysis

OBJECTIVE

To assess the association between maternal active cigarette smoking and the risk of oral clefts in the offspring.

STUDY DESIGN

Oral clefts are divided into three subgroups: total clefts, cleft lip with or without cleft palate (CL ± P), and cleft palate only (CP). Data from studies on different levels of smoking were gathered to examine the dose-response effect.

RESULTS

The present meta-analysis included 29 case-control and cohort studies through Cochrane, PubMed, and Ovid Medline searches. A modest but statistically significant association was found between maternal active smoking and CL ± P (odds ratio [OR] 1.368; 95% confidence interval [CI] 1.259-1.486) as well as CP (OR 1.241; 95% CI 1.117-1.378). Half the studies showed positive dose-response effect for each subgroup (test for linear trend, P < .05).

CONCLUSIONS

There is a moderate risk for having a child with a CL ± P or CP in women who smoke during pregnancy. We could not confirm whether there was a positive dose-response effect between maternal smoking and clefts.

Deleterious coding variants in multi-case families with non-syndromic cleft lip and/or palate phenotypes

Nonsyndromic Cleft Lip and/or Palate (NSCLP) is regarded as a multifactorial condition in which clefting is an isolated phenotype, distinguished from the largely monogenic, syndromic forms which include clefts among a spectrum of phenotypes. Nonsyndromic clefting has been shown to arise through complex interactions between genetic and environmental factors. However, there is increasing evidence that the broad NSCLP classification may include a proportion of cases showing familial patterns of inheritance and contain highly penetrant deleterious variation in specific genes. Through exome sequencing of multi-case families ascertained in Bogota, Colombia, we identify 28 non-synonymous single nucleotide variants that are considered damaging by at least one predictive score. We discuss the functional impact of candidate variants identified. In one family we find a coding variant in the MSX1 gene which is predicted damaging by multiple scores. This variant is in exon 2, a highly conserved region of the gene. Previous sequencing has suggested that mutations in MSX1 may account for ~2% of NSCLP. Our analysis further supports evidence that a proportion of NSCLP cases arise through monogenic coding mutations, though further work is required to unravel the complex interplay of genetics and environment involved in facial clefting.

Fine-Mapping of 18q21.1 Locus Identifies Single Nucleotide Polymorphisms Associated with Nonsyndromic Cleft Lip with or without Cleft Palate

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common congenital birth defects. NSCL/P is a complex multifactorial disease caused by interactions between multiple environmental and genetic factors. However, the causal single nucleotide polymorphism (SNP) signature profile underlying the risk of familial NSCL/P still remains unknown. We previously reported a 5.7-Mb genomic region on chromosome 18q21.1 locus that potentially contributes to autosomal dominant, low-penetrance inheritance of NSCL/P. In the current study, we performed exome sequencing on 12 familial genomes (six affected individuals, two obligate carriers, and four seemingly unaffected individuals) of a six-generation family to identify candidate SNPs associated with NSCL/P risk. Subsequently, targeted bidirectional DNA re-sequencing of polymerase chain reaction (PCR)-amplified high-risk regions of MYO5B gene and sequenom iPLEX genotpying of 29 candidate SNPs were performed on a larger set of 33 members of this NSCL/P family (10 affected + 4 obligate carriers + 19 unaffected relatives) to find SNPs significantly associated with NSCL/P trait. SNP vs. NSCL/P association analysis showed the MYO5B SNP rs183559995 GA genotype had an odds ratio of 18.09 (95% Confidence Interval = 1.86–176.34; gender-adjusted P = 0.0019) compared to the reference GG genotype. Additionally, the following SNPs were also found significantly associated with NSCL/P risk: rs1450425 (LOXHD1), rs6507992 (SKA1), rs78950893 (SMAD7), rs8097060, rs17713847 (SCARNA17), rs6507872 (CTIF), rs8091995 (CTIF), and rs17715416 (MYO5B). We could thus identify mutations in several genes as key candidate SNPs associated with the risk of NSCL/P in this large multi-generation family.

Natural bone fragmentation in the blind cave-dwelling fish, Astyanax mexicanus: candidate gene identification through integrative comparative genomics

Animals that colonize dark and nutrient-poor subterranean environments evolve numerous extreme phenotypes. These include dramatic changes to the craniofacial complex, many of which are under genetic control. These phenotypes can demonstrate asymmetric genetic signals wherein a QTL is detected on one side of the face but not the other. The causative gene(s) underlying QTL are difficult to identify with limited genomic resources. We approached this task by searching for candidate genes mediating fragmentation of the third suborbital bone (SO3) directly inferior to the orbit of the eye. We integrated positional genomic information using emerging Astyanax resources, and linked these intervals to homologous (syntenic) regions of the Danio rerio genome. We identified a discrete, approximately 6 Mb, conserved region wherein the gene causing SO3 fragmentation likely resides. We interrogated this interval for genes demonstrating significant differential expression using mRNA-seq analysis of cave and surface morphs across life history. We then assessed genes with known roles in craniofacial evolution and development based on GO term annotation. Finally, we screened coding sequence alterations in this region, identifying two key genes: transforming growth factor β3 (tgfb3) and bone morphogenetic protein 4 (bmp4). Of these candidates, tgfb3 is most promising as it demonstrates significant differential expression across multiple stages of development, maps close (<1 Mb) to the fragmentation critical locus, and is implicated in a variety of other animal systems (including humans) in non-syndromic clefting and malformations of the cranial sutures. Both abnormalities are analogous to the failure-to-fuse phenotype that we observe in SO3 fragmentation. This integrative approach will enable discovery of the causative genetic lesions leading to complex craniofacial features analogous to human craniofacial disorders. This work underscores the value of cave-dwelling fish as a powerful evolutionary model of craniofacial disease, and demonstrates the power of integrative system-level studies for informing the genetic basis of craniofacial aberrations in nature.

Systematic analysis of copy number variants of a large cohort of orofacial cleft patients identifies candidate genes for orofacial clefts

Orofacial clefts (OFCs) represent a large fraction of human birth defects and are one of the most common phenotypes affected by large copy number variants (CNVs). Due to the limited number of CNV patients in individual centers, CNV analyses of a large number of OFC patients are challenging. The present study analyzed 249 genomic deletions and 226 duplications from a cohort of 312 OFC patients reported in two publicly accessible databases of chromosome imbalance and phenotype in humans, DECIPHER and ECARUCA. Genomic regions deleted or duplicated in multiple patients were identified, and genes in these overlapping CNVs were prioritized based on the number of genes encompassed by the region and gene expression in embryonic mouse palate. Our analyses of these overlapping CNVs identified two genes known to be causative for human OFCs, SATB2 and MEIS2, and 12 genes (DGCR6, FGF2, FRZB, LETM1, MAPK3, SPRY1, THBS1, TSHZ1, TTC28, TULP4, WHSC1, WHSC2) that are associated with OFC or orofacial development. Additionally, we report 34 deleted and 24 duplicated genes that have not previously been associated with OFCs but are associated with the BMP, MAPK and RAC1 pathways. Statistical analyses show that the high number of overlapping CNVs is not due to random occurrence. The identified genes are not located in highly variable genomic regions in healthy populations and are significantly enriched for genes that are involved in orofacial development. In summary, we report a CNV analysis pipeline of a large cohort of OFC patients and identify novel candidate OFC genes.

Preaxial polydactyly associated with a MSX1 mutation and report of two novel mutations

We report two novel heterozygous missense MSX1 mutations in two Thai families (c.739C>T; p.Pro247Ser and c.607G>A; p.Ala203Thr). The p.Ala203Thr mutation was found in a female patient, her sister, and their father and is associated with unilateral cleft lip and palate, hypodontia, and microdontia. The p.Pro247Ser mutation was found in a three-generation Thai family and was associated with bilateral cleft lip and palate, hypodontia, microdontia, and dens invaginatus. The proband also had preaxial polydactyly of the left hand. The role of Msx1 in limb development in mice is discussed. Intrafamilial variability of the phenotypes is clearly evident. This is the first time that a limb anomaly has been reported to be associated with a mutation in MSX1.

From Bench to Bedside and Back: Improving Diagnosis and Treatment of Craniofacial Malformations Utilizing Animal Models

Craniofacial anomalies are among the most common birth defects and are associated with increased mortality and, in many cases, the need for lifelong treatment. Over the past few decades, dramatic advances in the surgical and medical care of these patients have led to marked improvements in patient outcomes. However, none of the treatments currently in clinical use address the underlying molecular causes of these disorders. Fortunately, the field of craniofacial developmental biology provides a strong foundation for improved diagnosis and for therapies that target the genetic causes of birth defects. In this chapter, we discuss recent advances in our understanding of the embryology of craniofacial conditions, and we focus on the use of animal models to guide rational therapies anchored in genetics and biochemistry.

Current Controversies in Diagnosis and Management of Cleft Palate and Velopharyngeal Insufficiency

Background. One of the most controversial topics concerning cleft palate is the diagnosis and treatment of velopharyngeal insufficiency (VPI). Objective. This paper reviews current genetic aspects of cleft palate, imaging diagnosis of VPI, the planning of operations for restoring velopharyngeal function during speech, and strategies for speech pathology treatment of articulation disorders in patients with cleft palate. Materials and Methods. An updated review of the scientific literature concerning genetic aspects of cleft palate was carried out. Current strategies for assessing and treating articulation disorders associated with cleft palate were analyzed. Imaging procedures for assessing velopharyngeal closure during speech were reviewed, including a recent method for performing intraoperative videonasopharyngoscopy. Results. Conclusions from the analysis of genetic aspects of syndromic and nonsyndromic cleft palate and their use in its diagnosis and management are presented. Strategies for classifying and treating articulation disorders in patients with cleft palate are presented. Preliminary results of the use of multiplanar videofluoroscopy as an outpatient procedure and intraoperative endoscopy for the planning of operations which aimed to correct VPI are presented. Conclusion. This paper presents current aspects of the diagnosis and management of patients with cleft palate and VPI including 3 main aspects: genetics and genomics, speech pathology and imaging diagnosis, and surgical management.

Screening of Transforming Growth Factor Beta 3 and Jagged2 Genes in the Malay Population with Nonsyndromic Cleft Lip with or without Cleft Palate

Objective

To determine the prevalence of mutations in transforming growth factor beta 3 (TGFβ3) and Jagged2 genes and their association with nonsyndromic cleft lip with or without cleft palate (CL±P) patients.

Design

Cross-sectional study on nonsyndromic CL±P and noncleft patients.

Setting

Reconstructive clinic and outpatient dental clinic, Hospital Universiti Sains Malaysia.

Patients

Blood samples of 96 nonsyndromic CL±P and 96 noncleft subjects.

Main Outcome Measure

Prevalence and association of mutations in TGFβ3 and Jagged2 genes with nonsyndromic CL±P.

Results

Most of the nonsyndromic CL±P patients (53.1%) had left unilateral CLP. There were slightly more females (56.6%) compared with males. The prevalence of the mutations in the TGFβ3 gene was 17.7% (95% confidence interval [CI]: 9.5, 24.5) and in the Jagged2 gene was 12.5% (95% CI: 5.5, 18.5), which was higher compared with the noncleft group. For the TGFβ3 gene, there was no mutation in the coding region in either of the groups. All variants were single nucleotide polymorphisms located within the intronic flanking region. Two variants were identified (g.15812T>G and g.15966A>G) in both nonsyndromic CL±P and noncleft patients. However, the association was not significant ( P > .05). Three variants (g.19779C>T, g.19547G>A, and g.19712C>T) were identified in the Jagged2 gene among nonsyndromic CL±P and noncleft patients. Only g.19712C>T showed a significant association with nonsyndromic CL±P patients ( P = .039).

Conclusion

g.19712C>T might play a crucial role in the development of cleft lip and palate. To the best of our knowledge, this is the first report of the mutation found within intron 13 of the Jagged2 gene among nonsyndromic CL±P Malay patients.

Evidence of the involvement of the polymorphisms near MSX1 gene in non-syndromic cleft lip with or without cleft palate

OBJECTIVE

Non-syndromic cleft lip, with or without cleft palate (NSCL/P) is a common craniofacial birth defect, characterised by an incomplete separation between nasal and oral cavities without any other congenital anomaly in humans. Several genes which play a role in cell differentiation, migration, growth and apoptosis, have been associated with clefting. The purpose of this study was to investigate the association between single-nucleotide polymorphisms (SNPs) near MSX1 gene and NSCL/P among South Indian population.

METHODS

A case-control analysis of five single nucleotide polymorphisms near MSX1 gene (rs11726039, rs868257, rs6446693, rs1907998 and rs6832405) was carried out in 173 patients with NSCL/P and 176 unaffected controls to determine their association with NSCL/P.

RESULTS

All SNPs were polymorphic in the study population. Comparisons of allele and genotype frequencies revealed that the C variant allele and the TC/CC genotypes of rs11726039 was significantly higher in controls than in the NSCL/P group (OR: 0.63; 95% CI: 0.41-0.097; p=0.037). However, neither of these findings remained significant after Bonferroni correction for multiple comparisons. The frequencies of rs868257, rs6446693, rs1907998 and rs6832405 minor alleles and genotypes were similar between the control and NSCL/P groups. No significant linkage disequilibrium (LD) was observed. Genotype-genotype interaction and the haplotype analysis did not reveal any significant association with NSCL/P.

CONCLUSIONS

The study results were suggestive of a positive association between MSX1 rs11726039 and NSCL/P in the South Indian population.

IRF6 Sequencing in Interrupted Clefting

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.

GFA Taq I polymorphism and cleft lip with or without cleft palate (CL/P) risk

The transforming growth factor alpha (TGFA) Taq I polymorphism has been indicated to be correlated with cleft lip with or without cleft palate (CL/P) susceptibility, but study results are still debatable. Thus, a meta-analysis was conducted. We conducted a comprehensive search of Embase, Ovid, Web of Science, the Cochrane database, PubMed, the Chinese Biomedical Literature Database (CBM-disc, 1979-2014), the database of National Knowledge Infrastructure (CNKI, 1979-2014) and the full paper database of Chinese Science and Technology of Chongqing (VIP, 1989-2014) to identify suitable studies. There were 18 studies suitable for this meta-analysis, involving a total of 3135 cases and 3575 controls. Significantly increased CL/P risk was observed (OR = 1.49; 95% CI 1.17-1.89; P = 0.001). In subgroup analyses stratified by ethnicity, there was evidence in the Caucasian population for an association between this polymorphism and CL/P risk (OR = 1.52; 95% CI 1.14-2.02; P = 0.004). However, no significant association was found between this his polymorphism and CL/P risk in African and Hispanic populations. According to a specific CL/P type, increased clip lip and palate risk and clip palate risk were found (OR = 1.38; 95% CI 1.10-1.73; P = 0.005; OR = 1.29; 95% CI 1.01-1.66; P = 0.042). In conclusion, the present meta-analysis found that the TGFA Taq I polymorphism may be associated with CL/P susceptibility.

Clinical Significance of First-Trimester Screening of the Retronasal Triangle for Identification of Primary Cleft Palate

OBJECTIVE

To investigate the use of the retronasal triangle (RNT) for identification of orofacial cleft (OC) in the first trimester and the clinical application of three-dimensional (3D) ultrasound techniques for confirming the diagnosis of OC.

METHODS

A total of 5,054 women with singleton pregnancies underwent first-trimester screening for Down syndrome at 11-13(+6) weeks. The RNT was scanned in each fetus, and 3D volumetric images of cases with abnormal or indeterminate RNT were obtained.

RESULTS

Satisfactory images were obtained from all cases. Seven cases (1.4‰) of abnormal RNT were diagnosed as OC in the first trimester, which were confirmed at a 16 weeks scan or at a postmortem examination. One case that was considered a normal RNT was diagnosed with OC at 22(+2) weeks and after term delivery. Six cases of indeterminate RNT were diagnosed as normal by 3D ultrasound. Identification of OC by visualization of the RNT in the first trimester had a sensitivity of 87.5% and a specificity of 99.9%.

CONCLUSION

The RNT is an important sonographic landmark that has a high sensitivity and specificity for the detection of OC in the first trimester. 3D ultrasound is an important tool that aids in confirming diagnosis of OC in the first and second trimesters.

Palatogenesis and cutaneous repair: A two-headed coin

BACKGROUND

The reparative mechanism that operates following post-natal cutaneous injury is a fundamental survival function that requires a well-orchestrated series of molecular and cellular events. At the end, the body will have closed the hole using processes like cellular proliferation, migration, differentiation and fusion.

RESULTS

These processes are similar to those occurring during embryogenesis and tissue morphogenesis. Palatogenesis, the formation of the palate from two independent palatal shelves growing towards each other and fusing, intuitively, shares many similarities with the closure of a cutaneous wound from the two migrating epithelial fronts.

CONCLUSIONS

In this review, we summarize the current information on cutaneous development, wound healing, palatogenesis and orofacial clefting and propose that orofacial clefting and wound healing are conserved processes that share common pathways and gene regulatory networks.

Studies of genes involved in craniofacial development and tumorigenesis: FGF3 contributes to isolated oral clefts and may interact with PAX9

OBJECTIVE

Previous studies suggest individuals born with oral clefts and their families have a higher susceptibility for cancer, which raises the hypothesis that these two conditions share common molecular pathways. This study evaluated the association between oral clefts and polymorphisms in genes that play a role in craniofacial and tumor development.

MATERIALS AND METHODS

Four hundred and ninety-seven subjects born with oral clefts and 823 unaffected subjects were recruited. Twenty-nine markers in 13 genes were genotyped by the Taqman method. Chi-square was used to compare allele and genotype frequencies. Bonferroni correction for multiple testing was used and the established alpha was 0.0003. This study also used logistic regression to test if genetic variants were associated with oral clefts using positive family history of cancer and age as covariates.

RESULTS

There was no association between family history of cancer and oral clefts (p = 0.51). None of the 1320 study participants had a diagnosis of cancer at the time of participation in the study. The marker rs4980700 in FGF3 was associated with oral clefts (p = 0.0002). Logistic regression analysis also provided evidence for gene-gene interaction between FGF3 (rs4980700) and PAX9 (rs2073242), increasing the risk for isolated oral clefts (p = 0.0003).

CONCLUSION

FGF3 is associated with oral clefts and may interact with PAX9.

Role of angiogenesis-related genes in cleft lip/palate: review of the literature

OBJECTIVES

Cleft lip and cleft palate (CLP) are the most common congenital craniofacial anomalies. They have a multifactorial etiology and result from an incomplete fusion of the facial buds. Two main mechanisms, acting alone or interacting with each other, were evidenced in this fusion defect responsible for CLP: defective tissue development and/or defective apoptosis in normal or defective tissues. The objective of this work was to study the implication and role of angiogenesis-related genes in the etiology of CL/P.

METHODS

Our methodological approach included a systematic and thorough analysis of the genes involved in CL/P (syndromic and non-syndromic forms) including previously identified genes but also genes that could potentially be angiogenesis-related (OMIM, Pub Med).We studied the interactions of these different genes and their relationships with potential environmental factors.

RESULTS

TGFβ, FGA, PDGFc, PDGFRa, FGF, FGFR1, FGFR2 growth factors as well as MMP and TIMP2 proteolytic enzymes are involved in the genesis of CLP (P>L). Furthermore, 18 genes involved in CLP also interact with angiogenesis-related genes.

DISCUSSION

Even if the main angiogenesis-related genes involved in CLP formation are genes participating in several biological activities and their implication might not be always related to angiogenesis defects, they nevertheless remain an undeniably important research pathway. Furthermore, their interactions with environmental factors make them good candidates in the field of CLP prevention.

Association of Transforming Growth Factor Alpha and Methylenetetrahydrofolate reductase gene variants with nonsyndromic cleft lip and palate in the Indian population

Objectives:

The aim was to evaluate the relationship of the K-primer variant of the transforming growth factor-alpha (TGF-α) gene and C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene with nonsyndromic cleft lip and palate (CL/P) in the Indian population.

Setting and Sample Population:

The study group consisted of DNA samples of 25 subjects with nonsyndromic CL with or without cleft palate and 25 unrelated controls, already existing in the Department of Orthodontics, D.A.P.M.R.V. Dental College, Bengaluru, Karnataka, India.

Materials and Methods:

The DNA samples were divided into two categories: Group A which included the 25 subjects with nonsyndromic CL/P; and Group B, which consisted of the 25 unrelated controls. The polymerase chain reaction (PCR) test was done for amplification of the region of interest from the DNA samples. Restriction digestion was then performed on the amplified product using the restriction enzyme HinfI, separately for each of the variants. The digested PCR products were separated into channels on a 1.5% agarose gel containing ethidium bromide in an electrophoretic chamber. A U.V. transilluminator was used to see the specific bands of base pairs of the digested PCR products.

Results:

In Group A, the TGF-α gene variant was present in 16 subjects (P = 0.001) and MTHFR gene variant was present in 8 subjects (P = 0.185). A combination of both gene variants were present in seven subjects, which was an interesting finding. In Group B, four subjects tested positive for the TGF-α and MTHFR gene variants.

Conclusions:

The TGF-α gene variant and a combination of TGF-α + MTHFR gene variants significantly contribute to the development of nonsyndromic CL/P and can be considered as genetic markers for Indian population. The MTHFR gene variant, though a minor risk factor, cannot be considered as a genetic marker.