Maternal alcohol binge-drinking in the first trimester and the risk of orofacial clefts in offspring: a large population-based pooling study

The Recurrent E-Cadherin (CDH1) Mutation c.760G>A Causes Orofacial Clefts but Does Not Predispose to Hereditary Cancer

Objective: Congenital, non-syndromic orofacial clefts (CL/P) are infrequently monogenic in etiology. However, heterozygous pathogenic CDH1 germline variants were reported in a few non-syndromic CL/P families, as well as in one syndromic form of CL/P: the blepharocheilodontic syndrome. CDH1 encodes epithelial cadherin (E-cadherin), and close to 300 different pathogenic CDH1 variants are listed in the ClinVar mutation database. The majority of CDH1 germline variants are implicated in hereditary diffuse gastric cancer (HDGC) susceptibility. The purpose of this study was to classify the CDH1 c.760G>A (p.Asp254Asn) mutation with respect to its resulting phenotype. Methods: Exome sequencing and targeted Sanger sequencing were performed in a family segregating CL/P. A review of pathogenic CDH1 variants in ClinVar and those identified in a PubMed/MEDLINE search was performed. Results: We identified a family with six individuals, who were 35-77 years old (mean 56 years) at their last examination, uniformly affected with bilateral CL/P. The CDH1 c.760G>A variant segregated with CL/P. This variant had been reported in 21 individuals, most often children and young adults, from six families. We determined a significant sex preponderance for this variant regarding CL/P: all 16 male and 5 of 11 female heterozygotes presented with CL/P. Furthermore, none of the heterozygous individuals in seven families reported any gastrointestinal tumors. Conclusions: The recurrent CDH1 c.760G>A mutation confers a high risk for CL/P, with strong male preponderance. This review of 27 mutation carriers, including 3 who were 68, 70, and 77 years of age, indicates that c.760G>A does not confer an increased risk for HDGC. The relevance of differentiating craniofacial from cancer phenotypes in mutation carriers is substantial for precision medicine and for counseling families.

Genome-wide study of gene-by-sex interactions identifies risks for cleft palate

Structural birth defects affect 3-4% of all live births and, depending on the type, tend to manifest in a sex-biased manner. Orofacial clefts (OFCs) are the most common craniofacial structural birth defects and are often divided into cleft lip with or without cleft palate (CL/P) and cleft palate only (CP). Previous studies have found sex-specific risks for CL/P, but these risks have yet to be evaluated in CP. CL/P is more common in males and CP is more frequently observed in females, so we hypothesized there would also be sex-specific differences for CP. Using a trio-based cohort, we performed sex-stratified genome-wide association studies (GWAS) based on proband sex followed by a genome-wide gene-by-sex (G × S) interaction testing. There were 13 loci significant for G × S interactions, with the top finding in LTBP1 (RR = 3.37 [2.04-5.56], p = 1.93 × 10-6). LTBP1 plays a role in regulating TGF-β bioavailability, and knockdown in both mice and zebrafish lead to craniofacial anomalies. Further, there is evidence for differential expression of LTBP1 between males and females in both mice and humans. Therefore, we tested the association between the imputed genetically regulated gene expression of genes with significant G × S interactions and the CP phenotype. We found significant association for LTBP1 in cell cultured fibroblasts in female probands (p = 0.0013) but not in males. Taken altogether, we show there are sex-specific risks for CP that are otherwise undetectable in a combined sex cohort, and LTBP1 is a candidate risk gene, particularly in females.

Genome-wide study of gene-by-sex interactions identifies risks for cleft palate

Structural birth defects affect 3-4% of all live births and, depending on the type, tend to manifest in a sex-biased manner. Orofacial clefts (OFCs) are the most common craniofacial structural birth defects and are often divided into cleft lip with or without cleft palate (CL/P) and cleft palate only (CP). Previous studies have found sex-specific risks for CL/P, but these risks have yet to be evaluated in CP. CL/P is more common in males and CP is more frequently observed in females, so we hypothesized there would also be sex-specific differences for CP. Using a trio-based cohort, we performed sex-stratified genome-wide association studies (GWAS) based on proband sex followed by a genome-wide gene-by-sex (GxS) interaction testing. There were 13 loci significant for GxS interactions, with the top finding in LTBP1 (RR=3.37 [2.04 - 5.56], p=1.93x10 -6 ). LTBP1 plays a role in regulating TGF-B bioavailability, and knockdown in both mice and zebrafish lead to craniofacial anomalies. Further, there is evidence for differential expression of LTBP1 between males and females in both mice and humans. Therefore, we tested the association between the imputed genetically regulated gene expression of genes with significant GxS interactions and the CP phenotype. We found significant association for LTBP1 in cell cultured fibroblasts in female probands (p=0.0013) but not in males. Taken altogether, we show there are sex-specific risks for CP that are otherwise undetectable in a combined sex cohort, and LTBP1 is a candidate risk gene, particularly in females.

Publicly funded healthcare costs associated with orofacial clefts for children born in Alberta, Canada between 2002 and 2018

BACKGROUND

Orofacial clefts (OFCs) include cleft palate (CP), cleft lip (CL), and cleft lip with cleft palate (CLP) and require multidisciplinary healthcare services. Alberta, Canada has a publicly funded, universal access healthcare system. This study determined publicly funded healthcare costs for children with an OFC and compared these costs to children without congenital anomalies.

METHODS

This retrospective population-based cohort analysis used the Alberta Congenital Anomalies Surveillance System to identify children born between 2002 and 2018 with an isolated OFC. They were matched 1:1 to a reference cohort based on sex and year of birth. The study population included 1614 children, from birth to 17 years of age linked to administrative databases to estimate annual inpatient and outpatient costs. Average annual all-cause costs were compared using two-sample independent t tests.

RESULTS

The mean total cleft-related costs per patient were highest for children with CLP ($74,138 CAD, standard deviation (SD) $43,447 CAD), followed by CP ($53,062 CAD, SD $74,366 CAD), and CL ($35,288 CAD, SD $49,720 CAD). The mean total all-cause costs per child were statistically significantly higher (p < .001) in children with an OFC ($56,305 CAD, SD $57,744 CAD) compared to children without a congenital anomaly ($18,600 CAD, SD $61,300 CAD).

CONCLUSIONS

Despite public health strategies to mitigate risk factors, the trend for OFCs has remained stable in Alberta, Canada for over 20 years. The costs reported are useful to other jurisdictions for comparison, and to families, healthcare professionals, service planners, and policy makers.

Unilateral Cleft lip and Palate: Long-Term Results of the Malek Technique

To review at 18 years-old the results of surgery and follow-up of children born in our hospital with unilateral cleft lip and palate (uCLP). They were operated at the time by the same surgeon, following the same primary surgical procedure (Malek).

Retrospective cohort study.

Tertiary Children's Hospital.

All children born with uCLP between 1996 and 2001 and operated in our hospital. Syndromic children were excluded.

Results of the primary surgery, ear-nose-throat interventions, maxillo-facial surgery and final phonatory results.

Seventy-nine files of children born with a cleft were reviewed: 34 were taken into consideration for uCLP: 15 right and 19 left. They were operated in two stages, following the inverse Malek procedure. Sixty per cent had a fistula. Eighty-eight percent had grommets. Ninety-seven percent had an alveolar graft at a median age of nine (5-10) and 22% underwent a Le Fort osteotomy. Seven percent were operated for a pharyngeal flap, 29% for a secondary lip surgery at a mean age of 12.8 and 29% for a late rhinoplasty at a mean age of 14.8 years. A median of 5.7 multidisciplinary consultations was realized with a median number of general anesthesia of 7.1 (4-13).

This retrospective study shows that the Malek procedure for children born with uCLP is related to a high risk of fistula but good long-term phonatory results. Twenty percent of children were operated for a Le Fort procedure and one-third for a secondary lip procedure and rhinoplasty.

Rare variant modifier analysis identifies variants in SEC24D associated with orofacial cleft subtypes

As one of the most common structural birth defects, orofacial clefts (OFCs) have been studied for decades, and recent studies have demonstrated that there are genetic differences between the different phenotypic presentations of OFCs. However, the contribution of rare genetic variation genome-wide to different subtypes of OFCs has been understudied, with most studies focusing on common genetic variation or rare variation within targeted regions of the genome. Therefore, we used whole-genome sequencing data from the Gabriella Miller Kids First Pediatric Research Program to conduct a gene-based burden analysis to test for genetic modifiers of cleft lip (CL) vs cleft lip and palate (CLP). We found that there was a significantly increased burden of rare variants in SEC24D in CL cases compared to CLP cases (p = 6.86 [Formula: see text] 10-7). Of the 15 variants within SEC24D, 53.3% were synonymous, but overlapped a known craniofacial enhancer. We then tested whether these variants could alter predicted transcription factor binding sites (TFBS), and found that the rare alleles destroyed binding sites for 9 transcription factors (TFs), including Pax1 (p = 0.0009), and created binding sites for 23 TFs, including Pax6 (p = 6.12 [Formula: see text] 10-5) and Pax9 (p = 0.0001), which are known to be involved in normal craniofacial development, suggesting a potential mechanism by which these synonymous variants could have a functional impact. Overall, this study indicates that rare genetic variation may contribute to the phenotypic heterogeneity of OFCs and suggests that regulatory variation may also contribute and warrant further investigation in future studies of genetic variants controlling risk to OFC.

Characterization of 554 Mexican Patients With Nonsyndromic Cleft Lip and Palate: Descriptive Study

Orofacial clefts are one of the most common birth defects and the most common craniofacial malformation worldwide. The most common orofacial clefts (OFCs) are congenital cleft lip with or without cleft palate (CL ± P) and isolated cleft palate (CP). The incidence of OFCs varies depending on region and ethnicity; however, it affects approximately 1 in 600 newborns worldwide. In most cases, CL ± P and CP are multifactorial congenital malformations, where both exogenous and genetic factors play an important role. The objective of this study was to describe the frequency of potential risk factors associated with the development of CL ± P and CP in Mexican population. Patients were referred for multisystemic treatment, from private and public institutions in different regions of the country (center, north, and south). Sociodemographic information, prenatal and parental history were obtained through direct interviews with the patients or the patients' mothers in the case of underaged patients. Referred patients were invited to participate in the study. No interventions were applied for this study. The relationship between these factors and the prevalence of CL ± P and CP was studied. A total of 554 patients were included, the majority with CLP (30% to 7%), statistically significant differences were found for folic acid ( P = 0.02) consumption. Familial aggregation did not reach statistical significance for first-degree family members ( P = 0.34) but was significant for second-degree family members ( P = 0.007). More risk factors associated with CL ± P and CP may still be unknown, prompting more epidemiological research and research in other little-studied areas, such as; specific genetic factors in Mexican population.

Antimicrobial Peptides and Interleukins in Cleft Soft Palate

Cleft palate is one of the most common and well-studied congenital anomalies; however, the role of protective tissue factors in its pathophysiology is still debated. The aim of our study was to evaluate interleukin and antimicrobial peptide appearance and distribution in cleft palate. Eight soft palate samples were obtained during veloplasty procedures. Immunohistochemical staining was applied to detect HBD-2-, HBD-3-, HBD-4-, LL-37-, IL-10-, and CD-163-positive cells via light microscopy. For statistical evaluation, the Mann-Whitney U test and Spearman's rank correlation coefficient were used. A significant difference between study groups was observed for HBD-2 and IL-10 in epithelial and connective tissue as well as HBD-4 in connective tissue. The number of HBD-3-positive cells was moderate in the patients, and few were observed in the controls. The number of LL-37-positive cells varied from a moderate amount to a numerous amount in both study groups, whilst CD-163 marked a moderate number of positive cells in patients, and a few-to-moderate amount was observed in the controls. Numerous correlations between studied factors were revealed in cleft tissues. The increase in antimicrobial peptides HBD-2 and HBD-4 and anti-inflammatory cytokine IL-10 suggested a wide compensatory elevation of the local immune system against cleft-raised tissue changes. The correlations between the studied factors (HBD-2, HBD-3, HBD-4, LL-37, and IL-10) proved the synergistic involvement of common local defense factors in postnatal cleft palate morphopathogenesis.

Variation of Tooth Crown Size in Cleft Lip and Palate Patients

AIM

This study aims to compare the mesiodistal (MD) and buccolingual (BL) tooth crown size (TCS) of adult patients with cleft lip and palate (CL/P) and patients without CL/P.

MATERIALS AND METHODS

The sample of this study consisted of 146 adult patients, of both genders, of which 73 were included in the case group (with CL/P) and 73 were included in the control group (without CL/P). Data regarding gender and age and cleft type were collected. In addition, dental models were evaluated to obtain the TCS in the maximum distance of the MD and BL dimensions of all erupted permanent teeth (except third molars). The results were submitted to statistical analysis with a significance level of 0.05.

RESULTS

In the upper arch, the central incisors (CI) were smaller in the case group for the MD and BL dimensions (p < 0.05). The lateral incisors (LI) and canine (C) were smaller only in the BL width (p < 0.05) and the second molars (SM), were smaller only in the MD dimensions. In the lower arch, there were significant differences only in the BL width between groups, the CI and LI presented smaller measurements in CL/P patients, while the left first molar (FM) and right first premolar (FPM) were larger (p < 0.05) than in patients without CL/P.

CONCLUSION

Patients with CL/P have different sizes in certain teeth compared to patients without CL/P.

CLINICAL RELEVANCE

Cleft lip and palate patients usually present important dental anomalies; thereby, the knowledge about trends in tooth size variations in CL/P patients can aid in dental and orthodontic treatment planning to obtain a stable, functional, and esthetic occlusion.

Rare genetic variants in SEC24D modify orofacial cleft phenotypes

As one of the most common structural birth defects, orofacial clefts (OFCs) have been studied for decades, and recent studies have demonstrated that there are genetic differences between the different phenotypic presentations of OFCs. However, the contribution of rare genetic variation genome-wide to different subtypes of OFCs has been understudied, with most studies focusing on common genetic variation or rare variation within targeted regions of the genome. Therefore, we used whole-genome sequencing data from the Gabriella Miller Kids First Pediatric Research Program to conduct a gene-based burden analysis to test for genetic modifiers of cleft lip (CL) vs cleft lip and palate (CLP). We found that there was a significantly increased burden of rare variants in SEC24D in CL cases compared to CLP cases (p=6.86×10-7). Of the 15 variants within SEC24D, 53.3% were synonymous, but overlapped a known craniofacial enhancer. We then tested whether these variants could alter predicted transcription factor binding sites (TFBS), and found that the rare alleles destroyed binding sites for 9 transcription factors (TFs), including Pax1 (p=0.0009), and created binding sites for 23 TFs, including Pax6 (p=6.12×10-5) and Pax9 (p= 0.0001), which are known to be involved in normal craniofacial development, suggesting a potential mechanism by which these synonymous variants could have a functional impact. Overall, this study demonstrates that rare genetic variation contributes to the phenotypic heterogeneity of OFCs and suggests that regulatory variation may also contribute and warrant further investigation in future studies of genetic variants controlling risk to OFC.

MicroRNAs and Gene Regulatory Networks Related to Cleft Lip and Palate

Cleft lip and palate is one of the most common congenital birth defects and has a complex etiology. Either genetic or environmental factors, or both, are involved at various degrees, and the type and severity of clefts vary. One of the longstanding questions is how environmental factors lead to craniofacial developmental anomalies. Recent studies highlight non-coding RNAs as potential epigenetic regulators in cleft lip and palate. In this review, we will discuss microRNAs, a type of small non-coding RNAs that can simultaneously regulate expression of many downstream target genes, as a causative mechanism of cleft lip and palate in humans and mice.

Modifiable Risk Factors of Non-Syndromic Orofacial Clefts: A Systematic Review

OFCs (orofacial clefts) are among the most frequent congenital defects, but their etiology has yet to be clarified. OFCs affect different structures and functions with social, psychological and economic implications in children and their families. Identifying modifiable risk factors is mandatory to prevent the occurrence of non-syndromic OFCs (NSOFCs). PubMed, Cochrane Library, Scopus and Web of Science were searched from 1 January 2012 to 25 May 2022 and a total of 7668 publications were identified. Studies focusing on the risk factors of NSOFCs were selected, leading to 62 case-control and randomized clinical trials. Risk factors were categorized into non-modifiable and modifiable. The first group includes genetic polymorphisms, gender of the newborn, ethnicity, and familiarity. Within the second group, risk factors that can only be modified before conception (consanguinity, parental age at conception, socio-economical and educational level, area of residency and climate), and risk factors modifiable before and after conception (weight, nutritional state, acute and chronic diseases, psychophysical stress, licit and illicit drugs, alcohol, smoke, pollutants and contaminants) have been distinguished. This study provides a wide overview of the risk factors of NSOFCs, focusing on modifiable ones, to suggest new perspectives in education, prevention, medical interventions and clinical research.

Gene×environment associations in orofacial clefting

This chapter reviews the evidence of gene×environment interactions (G×E) in the etiology of orofacial cleft birth defects (OFCs), specifically cleft lip (CL), cleft palate (CP), and cleft lip with or without cleft palate (CL/P). We summarize the current state of our understanding of the genetic architecture of nonsyndromic OFCs and the evidence that maternal exposures during pregnancy influence risk of OFCs. Further, we present possible candidate gene pathways for these exposures including metabolism of folates, metabolism of retinoids, retinoic acid receptor signaling, aryl hydrocarbon receptor signaling, glucocorticoid receptor signaling, and biotransformation and transport. We review genes in these pathways with prior evidence of association with OFCs, genes with evidence from prior candidate gene G×E studies, and genes identified from genome-wide searches specifically for identifying G×E. Finally, we suggest future directions for G×E research in OFCs.

Investigation of exposure to heavy metals (Hg, Pb, Cd, Co, and Cr) as the cause of congenital anomaly cases (orofacial cleft) in infants

Orofacial cleft (OFC) is one of the most common congenital defects, with worldwide cases occurring in approximately 1:700 to 1:1000 births. This incidence is among the highest birth defects in Indonesia, and the incidence rate in Bandung Regency (14.69%) is the second-highest in West Java province. The purpose of this study was to analyze the association of heavy metal factors that accumulate in infants to the risk of OFC in Bandung Regency. The method was used by testing heavy metals Hg, Pb, Cd, Co, and Cr in infant blood. The total sample were 54 samples, where the case respondent of 32 and 22 respondents as the control group. Blood samples were analyzed using ICP-MS Agilent 7900. The correlation using statistic analyze namely chi-square analysis (bivariate) and multiple logistic regression (multivariate). The results showed that there was a significant difference in the concentration of heavy metals Hg, Pb, and Cd as well as an increase in Pb and Cd in the infant's blood which was thought to be significantly associated with the risk of OFC.

Effect of Embryonic Alcohol Exposure on Craniofacial and Skin Melanocyte Development: Insights from Zebrafish (Danio rerio)

Alcohol is a common addictive substance and prenatal alcohol exposure could cause fetal alcohol spectrum disorder (FASD) and can lead to various birth defects. The small teleost zebrafish (Danio rerio) has been identified as a fine animal model in developmental biology and toxicological research. Zebrafish models are widely used to study the harmful effects of alcohol and limited studies are available on the craniofacial and skin malformations associated with FASD. The present study attempts to investigate the effect of alcohol on early zebrafish embryonic development. The effects of prenatal alcohol exposure on neural crest cell-derived organ formation, including pharyngeal dentition, palatal bones and skin melanocytes were analysed. Whole-mount cartilage and bone staining and imaging techniques were applied to determine the effects of alcohol on the above-mentioned structures. The tooth size and shape were affected by alcohol exposure, but the number of teeth in the pharyngeal dentition was not affected. Only first-generation teeth showed size differences. The alcohol-exposed ethmoid bone, which is homologous to the human hard palate, was smaller and less dense in cell arrangement compared with the control medial ethmoid bone. The skin pigmentation defects included reduced melanocyte density, melanin contraction, smaller melanocyte surface area and aberrations in melanosome dispersion, revealing that alcohol significantly influenced and downregulated each and every step of the melanocyte developmental process. This descriptive study summarises the effects of alcohol on the development of neural crest cell-derived structures and highlights the importance of zebrafish in studying the phenotypic characteristics of fetal alcohol spectrum disorder.

Environmental factors in non-syndromic orofacial clefts: A review based on meta-analyses results

Non-syndromic orofacial clefts (NSOFCs) are prevalent birth defects with a complex etiology where several interacting genetic and environmental factors have been observed. This narrative review describes maternal exposures that have been significantly associated with protective effects or risk factors. The statistically significant information reported here was found in meta-analysis studies, taking advantage of their precision in defining intervention effects and their management of heterogeneity between studies. In addition, I propose a hypothesis explaining the biological basis for the results of the meta-analyses. This review aims to improve the evidence available in parent counseling, to prevent the occurrence of orofacial clefts by suggesting lifestyle changes.

Novel risk factors for craniofacial microsomia and assessment of their utility in clinic diagnosis

Craniofacial microsomia (CFM, OMIM%164 210) is one of the most common congenital facial abnormalities worldwide, but it's genetic risk factors and environmental threats are poorly investigated, as well as their interaction, making the diagnosis and prenatal screening of CFM impossible. We perform a comprehensive association study on the largest CFM cohort of 6074 samples. We identify 15 significant (P < 5 × 10-8) associated genomic loci (including eight previously reported) and decipher 107 candidates based on multi-omics data. Gene Ontology term enrichment found that these candidates are mainly enriched in neural crest cell (NCC) development and hypoxic environment. Single-cell RNA-seq data of mouse embryo demonstrate that nine of them show dramatic expression change during early cranial NCC development whose dysplasia is involved in pathogeny of CFM. Furthermore, we construct a well-performed CFM risk-predicting model based on polygenic risk score (PRS) method and estimate seven environmental risk factors that interacting with PRS. Single-nucleotide polymorphism-based PRS is significantly associated with CFM [P = 7.22 × 10-58, odds ratio = 3.15, 95% confidence interval (CI) 2.74-3.63], and the top fifth percentile has a 6.8-fold CFM risk comparing with the 10th percentile. Father's smoking increases CFM risk as evidenced by interaction parameter of -0.324 (95% CI -0.578 to -0.070, P = 0.011) with PRS. In conclusion, the newly identified risk loci will significantly improve our understandings of genetics contribution to CFM. The risk prediction model is promising for CFM prediction, and father's smoking is a key environmental risk factor for CFM through interacting with genetic factors.

Environmental mechanisms of orofacial clefts

Orofacial clefts (OFCs) are among the most common birth defects and impart a significant burden on afflicted individuals and their families. It is increasingly understood that many nonsyndromic OFCs are a consequence of extrinsic factors, genetic susceptibilities, and interactions of the two. Therefore, understanding the environmental mechanisms of OFCs is important in the prevention of future cases. This review examines the molecular mechanisms associated with environmental factors that either protect against or increase the risk of OFCs. We focus on essential metabolic pathways, environmental signaling mechanisms, detoxification pathways, behavioral risk factors, and biological hazards that may disrupt orofacial development.

Identification of novel susceptibility loci for non-syndromic cleft lip with or without cleft palate

Although several genome‐wide association studies (GWAS) of non‐syndromic cleft lip with or without cleft palate (NSCL/P) have been reported, more novel association signals are remained to be exploited. Here, we performed an in‐depth analysis of our previously published Chinese GWAS cohort study with replication in an extra dbGaP case‐parent trios and another in‐house Nanjing cohort, and finally identified five novel significant association signals (rs11119445: 3’ of SERTAD4, P = 6.44 × 10⁻¹⁴; rs227227 and rs12561877: intron of SYT14, P = 5.02 × 10⁻¹³ and 2.80 × 10⁻¹¹, respectively; rs643118: intron of TRAF3IP3, P = 4.45 × 10⁻⁶; rs2095293: intron of NR6A1, P = 2.98 × 10⁻⁵). The mean (standard deviation) of the weighted genetic risk score (wGRS) from these SNPs was 1.83 (0.65) for NSCL/P cases and 1.58 (0.68) for controls, respectively (P = 2.67 × 10⁻¹⁶). Rs643118 was identified as a shared susceptible factor of NSCL/P among Asians and Europeans, while rs227227 may contribute to the risk of NSCL/P as well as NSCPO. In addition, sertad4 knockdown zebrafish models resulted in down‐regulation of sox2 and caused oedema around the heart and mandibular deficiency, compared with control embryos. Taken together, this study has improved our understanding of the genetic susceptibility to NSCL/P and provided further clues to its aetiology in the Chinese population.

Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio)

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.

A comprehensive analysis of AHRR gene as a candidate for cleft lip with or without cleft palate

Cleft lip and palate (CL/P) is among the most common congenital malformations and affects 1 in 700 newborns. CL/P is caused by genetic and environmental factors (maternal smoking, alcohol or drug use and others). Many genes and loci were associated with cleft lip/palate but the amount of heterogeneity justifies identifying new causal genes and variants. AHRR (Aryl-Hydrocarbon Receptor Repressor) gene has recently been related to CL/P however, few functional studies analyze the genotypephenotype interaction of AHRR with CL/P. Several studies associate the molecular pathway of AHRR to CL/P which indicates this gene as a functional candidate in CL/P etiology.

METHODS

Systematic Literature Review was performed using PUBMED database with the keywords cleft lip, cleft palate, orofacial cleft, AHRR and synonyms. SLR resulted in 37 included articles.

RESULTS

AHRR is a positional and functional candidate gene for CL/P. In silico analysis detected interactions with other genes previously associated to CL/P like ARNT and CYP1A1. AHRR protein regulates cellular toxicity through TCDD mediated AHR pathway. Exposure to TCDD in animal embryos is AHR mediated and lead to cleft palate due to palate fusion failure and post fusion rupture. AHRR regulates cellular growth and differentiation, fundamental to lip and palatogenesis. AHRR decreases carcinogenesis and recently a higher tumor risk has been described in CL/P patients and families. AHRR is also a smoking biomarker due to changed methylation sites found in smokers DNA although folate intake may partially revert these methylation alterations. This corroborates the role of maternal smoking and lack of folate supplementation as risk factors for CL/P.

CONCLUSION

This research identified the importance of AHRR in dioxin response and demonstrated an example of genetic and environmental interaction, indispensable in the development of many complex diseases.

ANTENATAL EVENTS AMONGST MOTHERS OF BABIES WITH OROFACIAL CLEFTS

BACKGROUND

Exogenous factors occurring in the antenatal period could be contributory to the formation of orofacial cleft. This study sought to determine the antenatal events in mothers that may have contributed to orofacial cleft deformity of their children.

METHODOLOGY

It was a prospective observational cross sectional study of consenting mothers of babies with orofacial cleft who met the inclusion criteria. The study instrument was a questionnaire.

RESULTS

Seventy-two mothers participated in the study. Most of these mothers were below 35 years of age and more than half, 43 (59.7%) were of the low-intermediate socioeconomic status. Although majority, 70 (97.2) of the mothers had antenatal care, the mean gestational age at commencement of antenatal care was 4 months. Almost all, 69 (95.8%) mothers had ultrasound scans however the detection of the orofacial cleft was in only 2 (2.8%) mothers. The commonest medication taken was haematinics, 26 (36.1%). Herbal medication, 15 (20.8%) and antimalarial, 12 (16.7%) were the other drugs more frequently taken. The mean age of pregnancy at commencement of these medications was 3.6 months.

CONCLUSION

Although uptake of antenatal service was common practice among mothers of babies with orofacial clefts in this study, no antenatal predisposing factors were identified.

Maternal multivitamin intake and orofacial clefts in offspring: Japan Environment and Children's Study (JECS) cohort study

OBJECTIVES

Orofacial clefts are common birth defects with a lack of strong evidence regarding their association with maternal nutrition. We aimed to determine whether a relationship exists between maternal nutrient or multivitamin intake and orofacial clefts.

DESIGN

This is a prospective, population-based nationwide cohort study.

SETTING

The study was conducted in 15 regional centres, consisting of local administrative units and study areas.

PARTICIPANTS

A total of 98 787 eligible mother-child pairs of the Japan Environment and Children's Study were included.

INTERVENTION

Exposures were maternal nutrition and the use of supplemental multivitamins in mothers.

PRIMARY AND SECONDARY OUTCOME MEASURES

Outcomes were the occurrence of any orofacial cleft at birth. Multinomial logistic regression analyses were used to evaluate the association between maternal multivitamin intake and the incidence of orofacial clefts.

RESULTS

Of the 98 787 children, 69 (0.07%) were diagnosed with cleft lip alone, 113 (0.11%) were diagnosed with cleft lip and palate, and 52 (0.05%) were diagnosed with cleft palate within 1 month after birth. Regarding the total orofacial cleft outcome, statistically significant point estimates of relative risk ratios (RR) were determined for multivitamin intake before pregnancy (RR=1.71; 95% CI 1.06 to 2.77) and during the first trimester (RR=2.00; 95% CI 1.18 to 3.37), but the association was not significant for multivitamin intake after the first trimester (RR=1.34; 95% CI 0.59 to 3.01). Maternal micronutrient intake via food was not associated with the incidence of orofacial clefts in offspring.

CONCLUSIONS

Intake of multivitamin supplements shortly before conception or during the first trimester of pregnancy was found to be associated with an increased incidence of orofacial clefts at birth. Pregnant women and those intending to become pregnant should be advised of the potential risks of multivitamin supplementation.

The prevalence of non-syndromic orofacial clefts and associated congenital heart diseases of a tertiary hospital in Riyadh, Saudi Arabia

Background

Orofacial clefts are considered one of the most common birth defects and are frequently associated with other malformations. Congenital heart disease is one of the most prevalent congenital malformation.

Objective

To investigate the prevalence of congenital heart diseases associated with non-syndromic orofacial clefts in the Saudi population.

Methods

Electronic files of non-syndromic orofacial cleft patients who visited the Oral and Maxillofacial Surgery Department in King Abdulaziz Medical City of Riyadh, Saudi Arabia from January 2015 to December 2018 were retrospectively reviewed. Data were recorded in an excel sheet and analyzed using SPSS via frequency tests.

Results

In the cleft children identified, the prevalence of non-syndromic orofacial clefts was (77%). Orofacial clefts showed a male predominance (62%). The most common orofacial phenotype was unilateral cleft lip and palate (34%). The prevalence of associated congenital malformations with orofacial clefts was (41%). The most prevalent congenital malformation was congenital heart disease (35%), mainly found in unilateral cleft lip and palate patients (33%). The prevalence of associated congenital heart disease with orofacial clefts was (19%). The most frequent type of congenital heart disease was atrial septal defect (37%).

Conclusion

This study highlights the recognition of the associated congenital heart disease with non-syndromic orofacial cleft patients. Global screening protocols designed for newborns with non-syndromic orofacial cleft are needed to eliminate late diagnosis of critical congenital heart diseases which might present operative risks of anesthesia and/or surgical procedures.

A Bibliometric Analysis of Cleft Lip and Palate-Related Publication Trends From 2000 to 2017

OBJECTIVE

Cleft lip and palate (CLP) is the most common human cranial and maxillofacial birth defect. The aim of this bibliometric analysis was to provide an overview of the development of CLP-related research.

METHOD

Cleft lip and palate-related studies published from 2000 to 2017 were retrieved from the Science Citation Index Expanded core database. Publication date, journal, authors, first authors, keywords, and citations were extracted and quantitatively analyzed using Bibliographic Item Co-Occurrence Matrix Builder software. The word matrix and co-occurrence matrix were established, and the co-citation analysis, keyword clustering, and social network analysis (SNA) of highly cited papers were completed.

RESULTS

A total of 9040 articles were retrieved from the 18 years of publications that were searched. The number of documents steadily increased over the period of interest, with a slight decrease in 2016 and 2017. This article separately examined the top most cited papers and high-frequency keywords from 3 time periods: 2000 to 2005, 2006 to 2011, and 2011 to 2017. The strategy coordinates of citation reflect TGF-β3, MSX1 gene, technique for cleft lip repair, TTF2, P63, IRF6 gene, FGF signaling, PVRL1, TGFBR2, and BMP4 gene as areas of research interest in the field. Moreover, the SNA of keywords highlighted new research topics: meta-analysis, cone beam computed tomography, tooth agenesis, case-control study, association study, micrognathia, DiGeorge syndrome, NSCL/P, UCLP, GWAS, MTHFR, and CLPTM1L.

CONCLUSION

We conducted bibliometric research of CLP across an 18-year span. The results help to define an overall command of the latest topics in CLP and provide insight for launching new projects.

Choanal atresia and stenosis: Development and diseases of the nasal cavity

Proper craniofacial development in vertebrates depends on growth and fusion of the facial processes during embryogenesis. Failure of any step in this process could lead to craniofacial anomalies such as facial clefting, which has been well studied with regard to its molecular etiology and cellular pathogenesis. Nasal cavity invagination is also a critical event in proper craniofacial development, and is required for the formation of a functional nasal cavity and airway. The nasal cavity must connect the nasopharynx with the primitive choanae to complete an airway from the nostril to the nasopharynx. In contrast to orofacial clefts, defects in nasal cavity and airway formation, such as choanal atresia (CA), in which the connection between the nasal airway and nasopharynx is physically blocked, have largely been understudied. This is also true for a narrowed connection between the nasal cavity and the nasopharynx, which is known as choanal stenosis (CS). CA occurs in approximately 1 in 5,000 live births, and can present in isolation but typically arises as part of a syndrome. Despite the fact that CA and CS usually require immediate intervention, and substantially affect the quality of life of affected individuals, the etiology and pathogenesis of CA and CS have remained elusive. In this review I focus on the process of nasal cavity development with respect to forming a functional airway and discuss the cellular behavior and molecular networks governing this process. Additionally, the etiology of human CA is discussed using examples of disorders which involve CA or CS. This article is categorized under: Signaling Pathways > Cell Fate Signaling Comparative Development and Evolution > Model Systems Birth Defects > Craniofacial and Nervous System Anomalies.

[Oral health management for children]

Pediatric dentistry should focus not only on the treatment of various oral diseases during the entire growth and development of children but also on the early prevention, diagnosis, and intervention of various oral diseases in this process. Early identification and removal of risk factors or early intervention for common oral diseases is necessary to the implementation of oral health management for pregnant women, infants, preschool and school-age children, and adolescents with different general and oral physiological characteristics and common oral diseases. The treatment enables the growth and development of the teeth, as well as occlusion and facials along the normal trajectory, ultimately achieving the functional perfection and aesthetic coordination of the cranio-maxillary and occlusion.

Risk factors and comorbidities in Brazilian patients with orofacial clefts

Considering that environmental risk factors substantially contribute to the etiology of orofacial clefts and that knowledge about the characteristics and comorbidities associated with oral clefts is fundamental to promoting better quality of life, this study aimed to describe the risk factors, main characteristics, and comorbidities of a group of patients with cleft lip and/or cleft palate (CL/P) from Rio Grande do Norte (RN), Brazil. Data were obtained from 173 patients with CL/P using a form from the Brazilian database on Orofacial Clefts. Most patients were male with cleft lip and palate and had a normal size and weight at birth; presented few neonatal intercurrent events; and had anemia and respiratory and cardiovascular diseases as main associated comorbidities. They also required timely surgical rehabilitation and multidisciplinary care to stimulate their neuropsychomotor development. In addition, a high frequency of familial recurrence and of parental consanguinity was evidenced in the studied population, especially for the cleft lip and cleft palate type. Other relevant findings were the considerable maternal exposure to alcohol, infections, smoking, and hypertension, as well as low supplementation with vitamins and minerals and deliberate consumption of analgesics, antibiotics, and antihypertensives during pregnancy. Characterization of the CL/P patient profile is essential for the planning of health services and integration among the health professionals involved in the diagnosis and treatment of these malformations. Our results reinforce the need for additional research to confirm the association between environmental factors and the development of orofacial clefts.

Gene-gene interaction between MSX1 and TP63 in Asian case-parent trios with nonsyndromic cleft lip with or without cleft palate

BACKGROUND

Small ubiquitin-like modification, also known as sumoylation, is a crucial post-translational regulatory mechanisms involved in development of the lip and palate. Recent studies reported two sumoylation target genes, MSX1 and TP63, to have achieved genome-wide level significance in tests of association with nonsyndromic clefts. Here, we performed a candidate gene analysis considering gene-gene and gene-environment interaction for SUMO1, MSX1, and TP63 to further explore the etiology of nonsyndromic cleft lip with or without cleft palate (NSCL/P).

METHODS

A total of 130 single-nucleotide polymorphisms (SNPs) in or near SUMO1, MSX1, and TP63 was analyzed among 1,038 Asian NSCL/P trios ascertained through an international consortium. Conditional logistic regression models were used to explore gene-gene (G × G) and gene-environment (G × E) interaction involving maternal environmental tobacco smoke and multivitamin supplementation. Bonferroni correction was used for G × E analysis and permutation tests were used for G × G analysis.

RESULTS

While transmission disequilibrium tests and gene-environment interaction analysis showed no significant results, we did find signals of gene-gene interaction between SNPs near MSX1 and TP63. Three pairwise interactions yielded significant p values in permutation tests (rs884690 and rs9290890 with p = 9.34 × 10^-5 and empirical p = 1.00 × 10^-4 , rs1022136 and rs4687098 with p = 2.41 × 10^-4 and empirical p = 2.95 × 10^-4 , rs6819546 and rs9681004 with p = 5.15 × 10^-4 and empirical p = 3.02 × 10^-4 ).

CONCLUSION

Gene-gene interaction between MSX1 and TP63 may influence the risk of NSCL/P in Asian populations. Our study provided additional understanding of the genetic etiology of NSCL/P and underlined the importance of considering gene-gene interaction in the etiology of this common craniofacial malformation.

Maternal Smoking during Pregnancy Is Associated with Offspring Hypodontia

Little is known about environmental risk factors for hypodontia. The objective of this study was to investigate the association between hypodontia and common environmental risk factors, such as maternal smoking and alcohol and caffeine consumption during pregnancy. Eighty-nine hypodontia cases with 1 or more missing permanent lateral incisors and/or 1 or more missing premolars were enrolled in this clinic-based case-control study. Some 253 controls with no missing teeth were frequency matched to cases by age and sex. Hypodontia was diagnosed using panoramic radiographs. Sociodemographic data were collected from both the participants and their mothers, with maternal self-reported active and passive smoking, as well as alcohol and caffeine consumption during pregnancy, assessed by a questionnaire. Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated with logistic regression to assess the strength of association between risk factors and hypodontia. OR estimates were then adjusted for possible confounders, such as maternal age at delivery, sex and gestational age of the child, and household socioeconomic background. Significant associations were found between hypodontia and maternal cigarette use during pregnancy, as well as the number of cigarettes smoked per day. The consumption of 10 or more cigarettes per day during pregnancy was associated with greater odds of having a child with hypodontia (adjusted OR, 4.18; 95% CI, 1.48-11.80; P = 0.007). Observed associations between hypodontia, second-hand smoke, and alcohol and caffeine consumption were not statistically significant. Maternal smoking during pregnancy is associated with hypodontia. Larger samples and prospective observational study designs, however, are needed to investigate this association further.

Interaction between smoking and body mass index and risk of oral clefts

PURPOSE

To examine maternal smoking and body mass index (BMI) interactions in contributing to risk of oral clefts.

METHODS

We studied 4935 cases and 10,557 controls from six population-based studies and estimated a pooled logistic regression of individual-level data, controlling for study fixed effects and individual-level risk factors.

RESULTS

We found a significant negative smoking-BMI interaction, with cleft risk with smoking generally declining with higher BMI. For all clefts combined, the odds ratio for smoking was 1.61 (95% confidence interval [CI]: 1.39-1.86) at BMI 17 (underweight), 1.47 (95% CI: 1.34-1.62) at BMI 22 (normal weight), 1.35 (95% CI: 1.22-1.48) at BMI 27 (overweight), 1.21 (95% CI: 1.04-1.41) at BMI 33 (obese), and 1.13 (95% CI: 0.92-1.38) at BMI 37 (very obese). A negative interaction was also observed for isolated clefts and across cleft types but was more pronounced for cleft lip only and cleft palate only.

CONCLUSIONS

Our findings suggest that the risk of oral clefts associated with maternal smoking is largest among underweight mothers, although the smoking-BMI interaction is strongest for cleft lip only and cleft palate only. BMI was not protective for the effects of smoking; a clinically relevant increase in smoking-related cleft risk was still present among heavier women.

Genetic factors influencing risk to orofacial clefts: today's challenges and tomorrow's opportunities

Orofacial clefts include cleft lip (CL), cleft palate (CP), and cleft lip and palate (CLP), which combined represent the largest group of craniofacial malformations in humans with an overall prevalence of one per 1,000 live births. Each of these birth defects shows strong familial aggregation, suggesting a major genetic component to their etiology. Genetic studies of orofacial clefts extend back centuries, but it has proven difficult to define any single etiologic mechanism because many genes appear to influence risk. Both linkage and association studies have identified several genes influencing risk, but these differ across families and across populations. Genome-wide association studies have identified almost two dozen different genes achieving genome-wide significance, and there are broad classes of 'causal genes' for orofacial clefts: a few genes strongly associated with risk and possibly directly responsible for Mendelian syndromes which include orofacial clefts as a key phenotypic feature of the syndrome, and multiple genes with modest individual effects on risk but capable of disrupting normal craniofacial development under the right circumstances (which may include exposure to environmental risk factors). Genomic sequencing studies are now underway which will no doubt reveal additional genes/regions where variants (sequence and structural) can play a role in controlling risk to orofacial clefts. The real challenge to medicine and public health is twofold: to identify specific genes and other etiologic factors in families with affected members and then to devise effective interventions for these different biological mechanisms controlling risk to complex and heterogeneous birth defects such as orofacial clefts.