Maternal alcohol consumption, alcohol metabolism genes, and the risk of oral clefts: a population-based case-control study in Norway, 1996-2001

Bone morphogenetic protein signaling pathway- Ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10 to 18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10 to 18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

The mediating role of abnormal ZEB1 methylation in the association between nickel exposure and non-syndromic orofacial cleft

Our previous study found a positive relationship between fetal nickel exposure and the risk of OFCs. The teratogenic mechanism of nickel is not clear. In this study, we aim to examine the mediating effect of DNA methylation on the association of nickel(Ni) exposure with NSOFC in fetuses. 10 cases and 10 controls was used for screening target gene by Illumina Infinium Methylation EPIC(850k) BeadChip. 36 cases and 78 controls was conducted to determine DNA methylation level of selected gene in umbilical cord blood by Mass spectrometry assay. Mediation analysis was used to evaluate the potential mediating effect of selected gene methylation on the relation between concentrations of Ni and the risk for NSOFC. In the discovery stage, ZEB1 gene was identified to be hypermethylated in both nickel exposure and NSOFC group for validation. In the verification stage, the overall average methylation level of ZEB1 was significant higher in NSOFC cases(median = 8.70, interquartile range(IQR): 5.75-11.53) as compared to controls (median = 5.35, IQR: 4.30-7.78). The risk for NSOFC was increased by 1.43-fold with hypermethylation of ZEB1. Significant correlation was observed between concentrations of Ni in umbilical cord and methylation level of ZEB1. The hypermethylation of ZEB1 had a mediating effect by 20.47 % of total effect of Ni on NSOFC risk. Hypermethylation of ZEB1 is associated with the risk for NSOFC and may partially explain the association between Ni exposure and NSOFC risk. Our findings provide new insights into the epigenetic mechanisms underlying NSOFC and suggesting potential targets for future therapeutic interventions.

Organotin exposure and DNA methylation in non-syndromic cleft lip and palate: Integrating findings from case-control studies and animal experiments

Human exposure to organotin is common but little is known about the adverse pregnancy outcomes. This study aimed to explore the association between organotin exposure and the risk of non-syndromic cleft lip with or without cleft palate (NSCL/P) and to explore the underlying mechanism. Placental samples (109 NSCL/P cases and 128 controls) were analyzed for 8 organotin concentrations, and subsequent animal experiments were conducted by administering tributyltin (TBT) during critical developmental periods. DNA methylation BeadChip analysis (12 NSCL/P and 12 controls), bisulfite Sequencing analysis (3 NSCL/P and 3 controls mice), and RNA sequencing were performed to explore epigenetic mechanisms. Logistic regression, LASSO regression, support vector machine, random forest, and mediation effect analysis were utilized to identify key genes related to TBT and NSCL/P. Only tributyltin met the detection criteria for further analysis among 8 compounds. The median levels of TBT in cases (8.93 ng/g) were statistically significantly higher than those in controls (5.33 ng/g). Excessive TBT exposure in maternal placenta was associated with an increased risk of NSCL/P (OR = 6.44, 95 % CI, 2.91-14.25) in humans, showing a dose-response relationship (p for trend <0.05). 288 differentially methylated CpG sites in 129 genes were identified between cases and controls. Tributyltin was associated with FGFR2 and SCD hypomethylation, which were identified as potential key genes associated with NSCL/P. Mediation analysis suggested that DNA methylation of FGFR2 and SCD may mediate the impact of TBT on NSCL/P occurrence. TBT exposure during the critical period in mice (GD8.5-GD15.5) can induce progeny NSCL/P. Altered FGFR2 and SCD hypomethylation and gene expression observed in response to TBT exposure in fetal mice. Excessive TBT exposure was associated with increased risks of human NSCL/P. TBT exposure can induce NSCL/P in fetal mice. FGFR2 and SCD were implicated in NSCL/P pathogenesis, potentially mediated by DNA methylation alterations.

Bone Morphogenetic Protein signaling pathway - ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10-18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10-18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

Highlights

Bmp pathway mutants are ethanol sensitive resulting in palate defects. Ethanol disrupts Bmp-dependent palate development independent of gata3 . Timing of ethanol sensitivity suggests ethanol disrupts Bmp-dependent epithelial morphogenesis.

Orofacial Clefts: Genetics of Cleft Lip and Palate

Orofacial clefting is considered one of the commonest birth defects worldwide. It presents as cleft lip only, isolated cleft palate or cleft lip and palate. The condition has a diverse genetic background influenced by gene-gene and gene-environment interaction, resulting in two main types, syndromic and nonsyndromic orofacial clefts. Orofacial clefts lead to significant physiological difficulties that affect feeding, speech and language development and other developmental aspects, which results in an increased social and financial burden on the affected individuals and their families. The management of cleft lip and palate is solely based on following a multidisciplinary team approach. In this narrative review article, we briefly summarize the different genetic causes of orofacial clefts and discuss some of the common syndromes and the approach to the management of orofacial clefts.

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-alcohol interactions in birth defects

Most human birth defects are thought to result from complex interactions between combinations of genetic and environmental factors. This is true even for conditions that, at face value, may appear simple and straightforward, like fetal alcohol spectrum disorders (FASD). FASD describe the full range of structural and neurological disruptions that result from prenatal alcohol exposure. While FASD require alcohol exposure, evidence from human and animal model studies demonstrate that additional genetic and/or environmental factors can influence the embryo's susceptibility to alcohol. Only a limited number of alcohol interactions in birth defects have been identified, with many sensitizing genetic and environmental factors likely yet to be identified. Because of this, while unsatisfying, there is no definitively "safe" dose of alcohol for all pregnancies. Determining these other factors, as well as mechanistically characterizing known interactions, is critical for better understanding and preventing FASD and requires combined scrutiny of human and model organism studies.

Condylar Changes after Maxillary Expansion in Children with Cleft Lip and Palate—A Three-Dimensional Retrospective Study

Background: The presence of posterior crossbite can trigger aesthetic and functional changes as mandibular asymmetry in individuals, contributing to asymmetrical muscle function. Mandibular asymmetry and respective condyle adaptation may be an etiological factor in temporomandibular disorder. This study aims to evaluate the effects of maxillary expansion on the position and angulation of the condyles as well as the intercondylar distance in children with cleft lip and palate. Methods: Twenty-five individuals with cleft lip and palate who underwent maxillary expansion were selected. Condylar changes were evaluated by cone beam computed tomography using the Pullinger and Hollender formula. To determine the statistically significant differences between the variables, the Student t-test and the Benjamini–Hochberg correction method for multiple comparisons were used. Results: No statistically significant differences between angulation and condylar position before and after maxillary expansion were found. The intercondylar distance tended to increase in growing individuals with cleft lip and palate after maxillary expansion. Conclusions: Intercondylar distance shows a tendency to increase after expansion regardless of the cleft phenotype. No differences were found in angulation and condylar position with the changes in occlusion resulting from maxillary expansion.

Evidence of detrimental effects of prenatal alcohol exposure on offspring birthweight and neurodevelopment from a systematic review of quasi-experimental studies

BACKGROUND

Systematic reviews of prenatal alcohol exposure effects generally only include conventional observational studies. However, estimates from such studies are prone to confounding and other biases.

OBJECTIVES

To systematically review the evidence on the effects of prenatal alcohol exposure from randomized controlled trials (RCTs) and observational designs using alternative analytical approaches to improve causal inference.

SEARCH STRATEGY

Medline, Embase, Web of Science, PsychINFO from inception to 21 June 2018. Manual searches of reference lists of retrieved papers.

SELECTION CRITERIA

RCTs of interventions to stop/reduce drinking in pregnancy and observational studies using alternative analytical methods (quasi-experimental studies e.g. Mendelian randomization and natural experiments, negative control comparisons) to determine the causal effects of prenatal alcohol exposure on pregnancy and longer-term offspring outcomes in human studies.

DATA COLLECTION AND ANALYSIS

One reviewer extracted data and another checked extracted data. Risk of bias was assessed using customized risk of bias tools. A narrative synthesis of findings was carried out and a meta-analysis for one outcome.

MAIN RESULTS

Twenty-three studies were included, representing five types of study design, including 1 RCT, 9 Mendelian randomization and 7 natural experiment studies, and reporting on over 30 outcomes. One study design-outcome combination included enough independent results to meta-analyse. Based on evidence from several studies, we found a likely causal detrimental role of prenatal alcohol exposure on cognitive outcomes, and weaker evidence for a role in low birthweight.

CONCLUSION

None of the included studies was judged to be at low risk of bias in all domains, results should therefore be interpreted with caution.

SYSTEMATIC REVIEW REGISTRATION

This study is registered with PROSPERO, registration number CRD42015015941.

Association between selected alkaline earth elements concentrations in umbilical cord and risk for cleft lip with or without cleft palate

The relationship between alkaline earth elements in utero exposure and the risk of cleft lip with or without cleft palate (CL ± P) remains unclear. We aimed to investigate the associations between the concentration of alkaline earth elements in umbilical cord and risk for CL ± P. A case-control study was carried out in this study, including 78 cases and 142 controls. Association between each metals and the risk of CL ± P were evaluated with conventional logistic regression, bayesian kernel machine regression and weighted quantile sum regression models. Logistic regression model indicated that in utero exposure to higher levels of Barium was associated with increasing risk for CL ± P (odds ratio = 2.79, 95% confidence interval, 1.22-6.38) and for cleft lip with cleft palate (odds ratio = 3.94, 95% confidence interval, 1.45-10.72). Bayesian kernel machine regression model showed the statistical association between the metals mixture and risk difference of CL ± P, and barium was associated with CL ± P risk when all other metals were held fixed at the 25th percentiles (risk difference = 1.07, 95% confidence interval, 1.01-1.14). In weighted quantile sum model, barium accounted for most of the weight index in the combined effect of the metals mixture. The weighted quantile sum index showed that a quartile increase in the index resulted in an increase odds of 1.69 (95% confidence interval, 1.16-2.46) for CL ± P and of 2.11 (95% confidence interval, 1.34-3.35) for CLP. No associations were found in the three statistical models between Calcium, Magnesium and Strontium and the risks of CL ± P. In conclusion, in utero exposure to mixtures of alkaline earth elements was associated with an increased risk for CL ± P, of which barium was likely to be important factors in the development.

Evaluating shared genetic influences on nonsyndromic cleft lip/palate and oropharyngeal neoplasms

It has been hypothesised that nonsyndromic cleft lip/palate (nsCL/P) and cancer may share aetiological risk factors. Population studies have found inconsistent evidence for increased incidence of cancer in nsCL/P cases, but several genes (e.g., CDH1, AXIN2) have been implicated in the aetiologies of both phenotypes. We aimed to evaluate shared genetic aetiology between nsCL/P and oral cavity/oropharyngeal cancers (OC/OPC), which affect similar anatomical regions. Using a primary sample of 5,048 OC/OPC cases and 5,450 controls of European ancestry and a replication sample of 750 cases and 336,319 controls from UK Biobank, we estimate genetic overlap using nsCL/P polygenic risk scores (PRS) with Mendelian randomization analyses performed to evaluate potential causal mechanisms. In the primary sample, we found strong evidence for an association between a nsCL/P PRS and increased odds of OC/OPC (per standard deviation increase in score, odds ratio [OR]: 1.09; 95% confidence interval [CI]: 1.04, 1.13; p = .000053). Although confidence intervals overlapped with the primary estimate, we did not find confirmatory evidence of an association between the PRS and OC/OPC in UK Biobank (OR 1.02; 95% CI: 0.95, 1.10; p = .55). Mendelian randomization analyses provided evidence that major nsCL/P risk variants are unlikely to influence OC/OPC. Our findings suggest possible shared genetic influences on nsCL/P and OC/OPC.

Population Attributable Fractions of Modifiable Risk Factors for Nonsyndromic Orofacial Clefts: A Prospective Cohort Study From the Japan Environment and Children's Study

Background

Population impact of modifiable risk factors on orofacial clefts is still unknown. This study aimed to estimate population attributable fractions (PAFs) of modifiable risk factors for nonsyndromic cleft lip with or without cleft palate (CL±P) and cleft palate only (CP) in Japan.

Methods

We conducted a prospective cohort study using data from the Japan Environment and Children’s Study, which recruited pregnant women from 2011 to 2014. We estimated the PAFs of maternal alcohol consumption, psychological distress, maternal active and passive smoking, abnormal body mass index (BMI) (<18.5 and ≥25 kg/m²), and non-use of a folic acid supplement during pregnancy for nonsyndromic CL±P and CP in babies.

Results

A total of 94,174 pairs of pregnant women and their single babies were included. Among them, there were 146 nonsyndromic CL±P cases and 41 nonsyndromic CP cases. The combined adjusted PAF for CL±P of the modifiable risk factors excluding maternal alcohol consumption was 34.3%. Only maternal alcohol consumption was not associated with CL±P risk. The adjusted PAFs for CL±P of psychological distress, maternal active and passive smoking, abnormal BMI, and non-use of a folic acid supplement were 1.4% (95% confidence interval [CI], −10.7 to 15.1%), 9.9% (95% CI, −7.0 to 26.9%), 10.8% (95% CI, −9.9 to 30.3%), 2.4% (95% CI, −7.5 to 14.0%), and 15.1% (95% CI, −17.8 to 41.0%), respectively. We could not obtain PAFs for CP due to the small sample size.

Conclusions

We reported the population impact of the modifiable risk factors on CL±P, but not CP. This study might be useful in planning the primary prevention of CL±P.

Uranium concentration in umbilical cord may increase the risk for orofacial clefts

BACKGROUND

Orofacial clefts (OFCs) are common kind of congenital malformations. The teratogenicity of uranium (U) has been documented in animal study that maternal exposure to U can increase incidence of external malformations including cleft palate. However, there is limited evidence of the association of in utero exposure to U with OFCs risk in humans.

OBJECTIVE

This study aimed to investigate the association between in utero exposure to U and the risk of OFCs and its subtypes.

METHOD

All subjects were from a case-control study in Shanxi Province, northern China. Eighty-four OFCs cases and 142 healthy controls were included in this study. We used U concentration in umbilical cord as biomarkers to represent intrauterine exposure, which was detected by inductively coupled plasma mass spectrometry. Unconditional logistic regression was used to investigated the association between U level and the risk of OFCs and its subtypes.

RESULTS

The median of U concentration in umbilical cord is 0.745 ng/g in case group and 0.455 ng/g in control group. When the U concentration was divided into two categories, high level of U exposure increased the risk of OFCs (OR: 2.08, 95% CI: 1.13-3.86) and its subtype cleft lip with cleft palate (CLP) (OR: 2.72, 95% CI: 1.21-6.14). When divided into three categories, high level of U elevated the risk for OFCs (OR: 2.40, 95% CI: 1.14-5.06) and CLP (OR: 3.04, 95% CI: 1.20-7.74). Meanwhile, a dose-response relationship between the U concentration and the risk of total OFCs (P for trend = 0.009) and CLP (P for trend = 0.007) was found.

CONCLUSION

Our study found that in utero exposure to high level of U was associated with increased risk of OFCs and its subtype CLP.

The causal web of foetal alcohol spectrum disorders: a review and causal diagram

Foetal alcohol spectrum disorders (FASDs) are a leading cause of developmental disability. Prenatal alcohol use is the sole necessary cause of FASD, but it is not always sufficient. Multiple factors influence a child's susceptibility to FASD following prenatal alcohol exposure. Much of the FASD risk factor literature has been limited to discussions of association, rather than causation. While knowledge of predictor variables is important for identifying who is most at risk of FASD and for targeting interventions, causal knowledge is important for identifying effective mechanisms for prevention and intervention programmes. We conducted a systematic search and narrative synthesis of the evidence and used this to create a causal diagram (directed acyclic graph; DAG) to describe the causal pathways to FASD. Our results show that the aetiology of FASD is multifaceted and complex. FASD risk is determined by a range of lifestyle, sociodemographic, maternal, social, gestational, and genetic factors. The causal diagram that we present in this review provides a comprehensive summary of causal risk factors for FASD and can be used as a tool to inform data collection and statistical modelling strategies to minimise bias in future studies of FASD.

Animal models of gene-alcohol interactions

Most birth defects arise from complex interactions between multiple genetic and environmental factors. However, our current understanding of how these interactions and their contributions affect birth defects remains incomplete. Human studies are limited in their ability to identify the fundamental causes of birth defects due to ethical and practical limitations. Animal models provide a great number of resources not available to human studies and they have been critical in advancing our understanding of birth defects and the complex interactions that underlie them. In this review, we discuss the use of animal models in the context of gene-environment interactions that underlie birth defects. We focus on alcohol which is the most common environmental factor associated with birth defects. Prenatal alcohol exposure leads to a wide range of cognitive impairments and structural deficits broadly termed fetal alcohol spectrum disorders (FASD). We discuss the broad impact of prenatal alcohol exposure on the developing embryo and elaborate on the current state of gene-alcohol interactions. Additionally, we discuss how animal models have informed our understanding of the genetics of FASD. Ultimately, these topics will provide insight into the use of animal models in understanding gene-environment interactions and their subsequent impact on birth defects.

Association Between Cleft Lip and/or Cleft Palate and Family History of Cancer: A Case-Control Study

BACKGROUND

Cleft lip and/or cleft palate (CL ± P) are among the most common congenital anomalies. Nevertheless, their etiologies remain poorly understood. Several studies have demonstrated increased rates of cancer among patients with CL ± P and their relatives, as well as increased risk of CL ± P among family members of cancer survivors. In addition, a number of possible genetic associations between cancer and CL ± P have been identified. However, these studies are limited by confounding factors that may be prevalent in these patients, such as tobacco exposure and perinatal complications.The purpose of this study was to quantitatively evaluate the association between family history of cancer and development of CL ± P in the child.

METHODS

A case-control study was conducted at the Cleft Hospital and the Bashir Hospital in Gujrat, Pakistan from December 2015 to December 2016. All new cases of CL ± P at the Cleft Hospital were included. Sociodemographically similar patients without congenital malformations at the Bashir Hospital served as controls. Risk factors associated with CL ± P were identified through bivariate analyses. Multiple logistic regressions were performed to calculate adjusted odds ratios of developing CL ± P.

RESULTS

There were 137 patients with CL ± P and 147 controls in the study. The following factors were statistically significantly associated with development of cleft: history of cancer in the family (P < 0.001), complications during pregnancy (P = 0.02), maternal hypertension during pregnancy (P = 0.01), mother not on any medications (P < 0.001), consanguineous marriage (parents are first or second cousins) (P = 0.03), lower socioeconomic status (P < 0.001), having a parent who smokes (P = 0.001), and history of miscarriage (P = 0.01). After adjustment for these variables, having a history of cancer in the family was independently associated with a 5.19 times increased odds of the child being born with CL ± P (95% confidence interval [CI], 1.57-17.03). Middle-class socioeconomic status (compared with lower) (odds ratio [OR], 0.36; 95% CI, 0.16-0.83), having a smoking parent (OR, 2.12; 95% CI, 1.05-4.28), and history of miscarriage (OR, 4.60; 95% CI, 1.21-17.54) were also statistically significantly associated with CL ± P within this model.

CONCLUSIONS

This study provides evidence for a relationship between CL ± P and cancer that has been adjusted for confounders traditionally associated with patients with CL ± P, thereby supporting the evidence of shared environmental and/or genetic etiologies.

Oxidative stress and DNA damage in the mechanism of fetal alcohol spectrum disorders

This review covers molecular mechanisms involving oxidative stress and DNA damage that may contribute to morphological and functional developmental disorders in animal models resulting from exposure to alcohol (ethanol, EtOH) in utero or in embryo culture. Components covered include: (a) a brief overview of EtOH metabolism and embryopathic mechanisms other than oxidative stress; (b) mechanisms within the embryo and fetal brain by which EtOH increases the formation of reactive oxygen species (ROS); (c) critical embryonic/fetal antioxidative enzymes and substrates that detoxify ROS; (d) mechanisms by which ROS can alter development, including ROS-mediated signal transduction and oxidative DNA damage, the latter of which leads to pathogenic genetic (mutations) and epigenetic changes; (e) pathways of DNA repair that mitigate the pathogenic effects of DNA damage; (f) related indirect mechanisms by which EtOH enhances risk, for example by enhancing the degradation of some DNA repair proteins; and, (g) embryonic/fetal pathways like NRF2 that regulate the levels of many of the above components. Particular attention is paid to studies in which chemical and/or genetic manipulation of the above mechanisms has been shown to alter the ability of EtOH to adversely affect development. Alterations in the above components are also discussed in terms of: (a) individual embryonic and fetal determinants of risk and (b) potential risk biomarkers and mitigating strategies. FASD risk is likely increased in progeny which/who are biochemically predisposed via genetic and/or environmental mechanisms, including enhanced pathways for ROS formation and/or deficient pathways for ROS detoxification or DNA repair.

Association between selected essential trace element concentrations in umbilical cord and risk for cleft lip with or without cleft palate: A case-control study

A deficiency or excess of zinc (Zn), selenium (Se), cobalt (Co), molybdenum (Mo), or manganese (Mn) may interfere with fetal organogenesis. However, the impact of these essential trace elements on the occurrence of cleft lip with or without cleft palate (CL ± P) remains to be elucidated. We aimed to investigate the associations between the amounts of Zn, Se, Co, Mo, and Mn in umbilical cord tissue and risk for CL ± P. This case-control study included 200 controls without congenital malformations and 88 CL ± P cases. Zn, Se, Co, Mo, and Mn concentrations in the umbilical cord were determined using inductively coupled plasma mass spectrometry. Information was collected on demographics, lifestyle behaviors, and dietary intake. The median concentrations of Zn in cases of CL ± P and cleft lip with cleft palate (CLP), of Se in cases of CL ± P and cleft lip only (CLO), and of Co in cases of CLO were lower than in the controls. In utero exposure to higher levels of Zn was associated with reduced risk for CL ± P (OR = 0.44, 95% CI, 0.20-0.93) and for CLP (OR = 0.35, 95% CI, 0.14-0.86), and a higher level of Se was associated with reduced risk for CL ± P and CLO, with ORs of 0.47 (95% CI, 0.23-0.95) and 0.22 (95% CI, 0.08-0.67), respectively. By contrast, higher levels of Mo in the umbilical cord were associated with 2.52-fold (95% CI, 1.23-5.20) and 2.59-fold (95% CI, 1.12-5.95) higher risk for CL ± P and CLP, respectively. No association was found between Co or Mn and risk for CL ± P. In conclusion, in utero exposure to higher levels of Zn and Se was associated with reduced risk for CL ± P, but higher levels of Mo were associated with increased risk for CL ± P.

A comparison of DNA methylation in newborn blood samples from infants with and without orofacial clefts

Background

Isolated orofacial clefts are among the most common congenital birth defects. Although the underlying biological mechanisms remain largely unknown, clefts are thought to be complex disorders influenced by genetic, environmental, and potentially epigenetic factors.

Methods

In blood samples from 2- to 3-day-old infants (n = 747) collected in a nationwide population-based study of orofacial clefts in Norway, we measured DNA methylation profiles for more than 450,000 CpGs and then conducted epigenome-wide association analyses (EWAS). We tested methylation profile difference at each CpG between controls (n = 436) and each of the cleft subtypes (92 cleft lip only, CLO; 84 cleft palate only, CPO; 132 cleft lip and palate, CLP). We also compared controls to various combinations of case groups and compared case subtypes to each other. Finally, using the EWAS results, we searched for larger differentially methylated regions (DMRs) associated with orofacial clefts.

Results

In EWAS comparing controls to individual cleft subtypes, we found no significant associations at a Bonferroni P value threshold of 10⁻⁷. After pooling case groups, we found two significantly differentially methylated CpGs: cg09696939 near gene BICC1 is associated with CLO+CLP (P = 9.58 × 10⁻⁸); cg26985354 in gene CLASRP is associated with CPO+CLP (P = 7.38 × 10⁻⁸). In DMR analysis, we identified a total of 56 significant regions when comparing controls to individual cleft subtypes (10 for CLO, 6 for CPO, 41 for CLP). Only one DMR is shared among the three cleft groups. In combined case group analysis, we found 26 DMRs for CLP+CLO, 31 for CLP+CPO, and 37 when all subtypes are combined. Finally, in case-case comparisons of subtypes, we identified 10 DMRs when comparing CLP to CPO, 9 in CLP compared to CLO, and 13 in CLP compared to CPO.

Conclusions

We identified two individual CpGs and multiple DMRs that differ between controls and cleft case subtypes. Although we find some evidence for the possible role of DNA methylation in etiology of orofacial clefts, our study does not support previous reports of widespread differences in blood DNA methylation between babies with and without facial clefts.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0638-9) contains supplementary material, which is available to authorized users.

Disruption of Hedgehog Signaling by Vismodegib Leads to Cleft Palate and Delayed Osteogenesis in Experimental Design

The function of hedgehog signaling has previously been shown to be crucial for craniofacial development. In this study, we treated C57/BL6J mice with the hedgehog pathway inhibitor vismodegib by oral gavage to establish a stable vismodegib-induced cleft palate model. At E10.5 and E12.5, mice in the experimental group were treated with 100 mg/kg of vismodegib, whereas mice in the control group were treated with solvent. The treated pregnant mice were sacrificed on E13.5, E14.5, E15.5, and E16.5. Palatal shelf growth was evaluated via histological and immunohistochemical analyses as well as palatal organ culture. Immunohistochemical staining was performed to examine the expression of osteogenic proteins in the palatal tissue. A high proportion of the mice administered 2 doses of 100 mg/kg of vismodegib displayed a cleft palate. Histologic examination revealed severely retarded palatal shelf growth and thickened epithelium in the experimental group. Vismodegib exposure induced complete cleft palate, which was attributed to a reduced cell proliferation rate in the palatal mesenchyme along the anterior-posterior axis. Moreover, this model also showed delayed ossification in the region of palatine bone with downregulation of Indian hedgehog (Ihh) protein. Our results suggest that vismodegib can be used to inhibit hedgehog signaling to affect palatal morphogenesis. Under treatment with this exogenous inhibitor, the cell proliferation rate of the palatal shelves and the osteogenic potential of the hard palate were decreased, which likely contributed to the complete cleft palate.

Gene-environment interactions in development and disease

Developmental geneticists continue to make substantial jumps in our understanding of the genetic pathways that regulate development. This understanding stems predominantly from analyses of genetically tractable model organisms developing in laboratory environments. This environment is vastly different from that in which human development occurs. As such, most causes of developmental defects in humans are thought to involve multifactorial gene-gene and gene-environment interactions. In this review, we discuss how gene-environment interactions with environmental teratogens may predispose embryos to structural malformations. We elaborate on the growing number of gene-ethanol interactions that might underlie susceptibility to fetal alcohol spectrum disorders. WIREs Dev Biol 2017, 6:e247. doi: 10.1002/wdev.247 For further resources related to this article, please visit the WIREs website.

Environmental factors related to the occurrence of oral clefts in a Brazilian subpopulation

Background:

A cross-sectional study was conducted at the Craniofacial Rehabilitation Center in the General Hospital of the University of Cuiabá, Cuiabá city, Mato Grosso, Brazil.

Materials and Methods:

Poisson regression model was used to analyze the relationship between antenatal factors and the occurrence of oral clefts in 116 patients.

Results:

Oral clefts were more common in males (64.66%) and White race (46.02%). The mean age of the children was 21.91 months. The most common type of cleft was cleft lip and palate (CLP, 55.17%). Maternal and paternal smoking in the first trimester of pregnancy and parity were significantly associated with the occurrence of CLP. Parent's age, educational level, and occupation did not interfere in the occurrence of oral clefts. There was also no significant association between maternal illness, medication use, alcohol consumption, and maternal exposure to chemicals in the first trimester of pregnancy and the occurrence of clefts in this population.

Conclusion:

The analysis of the environmental factors present during the pregnancy of children with oral clefts revealed a significant association between parity (second onward), maternal smoking, and paternal smoking and the occurrence of CL and/or palate in this population.

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

Using individual participant data from six population-based case–control studies, we conducted pooled analyses to examine maternal alcohol consumption and the risk of clefts among >4600 infants with cleft lip only, cleft lip with cleft palate, or cleft palate only and >10,000 unaffected controls. We examined two first-trimester alcohol measures: average number of drinks/sitting and maximum number of drinks/sitting, with five studies contributing to each analysis. Study-specific odds ratios (ORs) were estimated using logistic regression and pooled to generate adjusted summary ORs. Across studies, 0.9–3.2 % of control mothers reported drinking an average of 5+ drinks/sitting, while 1.4–23.5 % reported drinking a maximum of 5+ drinks/sitting. Compared with non-drinkers, mothers who drank an average of 5+ drinks/sitting were more likely to deliver an infant with cleft lip only (pooled OR 1.48; 95 % confidence intervals 1.01, 2.18). The estimate was higher among women who drank at this level 3+ times (pooled OR 1.95; 1.23, 3.11). Ever drinking a maximum of 5+ drinks/sitting and non-binge drinking were not associated with cleft risk. Repeated heavy maternal alcohol consumption was associated with an increased risk of cleft lip only in offspring. There was little evidence of increased risk for other cleft types or alcohol measures.

The Genetics of Fetal Alcohol Spectrum Disorders

The term "fetal alcohol spectrum disorders" (FASD) defines the full range of ethanol (EtOH)-induced birth defects. Numerous variables influence the phenotypic outcomes of embryonic EtOH exposure. Among these variables, genetics appears to play an important role, yet our understanding of the genetic predisposition to FASD is still in its infancy. We review the current literature that relates to the genetics of FASD susceptibility and gene-EtOH interactions. Where possible, we comment on potential mechanisms of reported gene-EtOH interactions. Early indications of genetic sensitivity to FASD came from human and animal studies using twins or inbred strains, respectively. These analyses prompted searches for susceptibility loci involved in EtOH metabolism and analyses of candidate loci, based on phenotypes observed in FASD. More recently, genetic screens in animal models have provided an additional insight into the genetics of FASD. Understanding FASD requires that we understand the many factors influencing phenotypic outcome following embryonic EtOH exposure. We are gaining ground on understanding some of the genetics behind FASD, yet much work remains to be carried out. Coordinated analyses using human patients and animal models are likely to be highly fruitful in uncovering the genetics behind FASD.

Association between maternal smoking, gender, and cleft lip and palate

Introduction

Cleft lip and/or palate (CL/P) represent the most common congenital anomalies of the face.

Objective

To assess the relationship between maternal smoking, gender and CL/P.

Methods

This is an epidemiological cross-sectional study. We interviewed 1519 mothers divided into two groups: Cases: mothers of children with CL/P (n = 843) and Controls: mothers of children without CL/P (n = 676). All mothers were classified as smoker or non-smoker subjects during the first trimester of pregnancy. To determine an association among maternal smoking, gender, and CL/P, odds ratios were calculated and the adjustment was made by a logistic regression model.

Results

An association between maternal smoking and the presence of cleft was observed. There was also a strong association between male gender and the presence of cleft (OR = 3.51; 95% CI 2.83–4.37). By binary logistic regression analysis, it was demonstrated that both variables were independently associated with clefts. In a multivariate analysis, male gender and maternal smoking had a 2.5- and a 1.5-time greater chance of having a cleft, respectively.

Conclusion

Our findings are consistent with a positive association between maternal smoking during pregnancy and CL/P in male gender. The results support the importance of smoking prevention and introduction of cessation programs among women with childbearing potential.

Adjusting for bias due to incomplete case ascertainment in case-control studies of birth defects

Case-control studies of birth defects might be subject to selection bias when there is incomplete ascertainment of cases among pregnancies that are terminated after a prenatal diagnosis of the defect. We propose a simple method to estimate inverse probability of selection weights (IPSWs) for cases ascertained from both pregnancies that end in termination and those that do not end in termination using data directly available from the National Birth Defects Prevention Study and other published information. The IPSWs can then be used to adjust for selection bias analytically. We can also allow for uncertainty in the selection probabilities through probabilistic bias analysis. We provide an illustrative example using data from National Birth Defects Prevention Study (1997-2009) to examine the association between prepregnancy obesity (body mass index, measured as weight in kilograms divided by height in meters squared, of ≥30 vs. <30) and spina bifida. The unadjusted odds ratio for the association between prepregnancy obesity and spina bifida was 1.48 (95% confidence interval: 1.26, 1.73), and the simple selection bias-adjusted odds ratio was 1.26 (95% confidence interval: 1.04, 1.53). The probabilistic bias analysis resulted in a median adjusted odds ratio of 1.22 (95% simulation interval: 0.97, 1.47). The proposed method provides a quantitative estimate of the IPSWs and the bias introduced by incomplete ascertainment of cases among terminated pregnancies conditional on a set of assumptions.

Ancestral experience as a game changer in stress vulnerability and disease outcomes

Stress is one of the most powerful experiences to influence health and disease. Through epigenetic mechanisms, stress may generate a footprint that propagates to subsequent generations. Programming by prenatal stress or adverse experience in parents, grandparents, or earlier generations may thus be a critical determinant of lifetime health trajectories. Changes in regulation of microRNAs (miRNAs) by stress may enhance the vulnerability to certain pathogenic factors. This review explores the hypothesis that miRNAs represent stress-responsive elements in epigenetic regulation that are potentially heritable. Recent findings suggest that miRNAs are key players linking adverse early environments or ancestral stress with disease risk, thus they represent useful predictive disease biomarkers. Since miRNA signatures of disease are potentially heritable, big data management platforms will be vital to harness multi-generational information and capture succinct yet potent biomarkers capable of directing preventative treatments. This feature would offer a unique window of opportunity to advance personalized medicine.

Oral clefting in china over the last decade: 205,679 patients

Background:

China is the most populated country and has one of the highest prevalences of oral clefting. The present study reports the epidemiology and surgical procedures performed on the largest reported cohort of individuals with clefting in China.

Methods:

A retrospective review of patients who received cleft repair through Smile Train in China from 2000 to 2011 was conducted. Data on demographics, cleft characteristics, associated malformations, pregnancy and family history, and surgical technique were analyzed using SPSS (IBM, Chicago, Ill.).

Results:

A total of 205,679 patients underwent 209,169 cleft procedures. Cleft lip and palate (42.7%) was most common followed by isolated cleft palate (32.4%) and isolated cleft lip (24.9%). Males accounted for 63.5% of cases. The average age at initial surgery was 6.12 years. By 2011, this decreased to 1.8 years of age for lip repair and to 5.9 years of age for palate repair. The preferred techniques were rotation-advancement (55%) for unilateral lip repair and Von-Langenbeck (38%) and pushback (39%) for palate repair. The percentages of cases with associated anomalies and surgical complications were 12.8% and 0.36%, respectively.

Conclusions:

This study provides insight into cleft care in China as it reports the largest cohort of cleft patients treated by surgeons to date. Our results generally follow trends previously reported in China and developed countries. The male:female ratio for cleft palate patients was higher than expected. The average age at primary repair is higher than recommended, but seems to be decreasing.

Classification, epidemiology, and genetics of orofacial clefts

Orofacial clefts (OFCs) include a broad range of facial conditions that differ in cause and disease burden. In the published literature, there is substantial ambiguity in both terminology and classification of OFCs. This article discusses the terminology and classification of OFCs and the epidemiology of OFCs. Demographic, environmental, and genetic risk factors for OFCs are described, including suggestions for family counseling. This article enables clinicians to counsel families regarding the occurrence and recurrence of OFCs. Although much of the information is detailed, it is intended to be accessible to all health professionals for use in their clinical practices.

Genome-wide association study of maternal and inherited effects on left-sided cardiac malformations

Congenital left-sided lesions (LSLs) are serious, heritable malformations of the heart. However, little is known about the genetic causes of LSLs. This study was undertaken to identify common variants acting through the genotype of the affected individual (i.e. case) or the mother (e.g. via an in utero effect) that influence the risk of LSLs. A genome-wide association study (GWAS) was performed using data from 377 LSL case-parent triads, with follow-up studies in an independent sample of 224 triads and analysis of the combined data. Associations with both the case and maternal genotypes were assessed using log-linear analyses under an additive model. An association between LSLs and the case genotype for one intergenic SNP on chromosome 16 achieved genome-wide significance in the combined data (rs8061121, combined P = 4.0 × 10(-9); relative risk to heterozygote: 2.6, 95% CI: 1.9-3.7). In the combined data, there was also suggestive evidence of association between LSLs and the case genotype for a variant in the synaptoporin gene (rs1975649, combined P = 3.4 × 10(-7); relative risk to heterozygote: 1.6, 95% CI: 1.4-2.0) and between LSLs and the maternal genotype for an intergenic SNP on chromosome 10 (rs11008222, combined P = 6.3 × 10(-7); relative risk to heterozygote: 1.6, 95% CI: 1.4-2.0). This is the first GWAS of LSLs to evaluate associations with both the case and maternal genotypes. The results of this study identify three candidate LSL susceptibility loci, including one that appears to be associated with the risk of LSLs via the maternal genotype.

Genetics of cleft lip and cleft palate

Orofacial clefts are common birth defects and can occur as isolated, nonsyndromic events or as part of Mendelian syndromes. There is substantial phenotypic diversity in individuals with these birth defects and their family members: from subclinical phenotypes to associated syndromic features that is mirrored by the many genes that contribute to the etiology of these disorders. Identification of these genes and loci has been the result of decades of research using multiple genetic approaches. Significant progress has been made recently due to advances in sequencing and genotyping technologies, primarily through the use of whole exome sequencing and genome-wide association studies. Future progress will hinge on identifying functional variants, investigation of pathway and other interactions, and inclusion of phenotypic and ethnic diversity in studies.

Correlates of unprotected sexual intercourse among women who inject drugs or who have sexual partners who inject drugs in St Petersburg, Russia

OBJECTIVES

To assess risk for unintended pregnancy, this study describes the correlates of unprotected sexual intercourse (UPSI) among women who inject illicit drugs or who have sexual partners who inject drugs in St Petersburg, Russia.

METHODS

Data from a cross-sectional survey and biological test results collected between 2005 and 2008 from 202 Russian women (143 drug injectors and 59 non-drug injectors) were analysed. Multivariate regression was used to investigate the correlates of UPSI occurring at the women's last sexual act. Independent variables included socio-demographics, age at sexual debut, first sexual encounter perceived as involuntary, number of pregnancies and number of children for which the participant is the primary caretaker, heavy sporadic drinking (i.e. consuming more than five drinks in 2&emsp14;hours at least twice a month), at-risk drinking per the Alcohol Use Disorder Identification Test (AUDIT-C) score, and sexually transmitted infections (HIV-1, syphilis serology, Chlamydia trachomatis and Neisseria gonorrheae).

RESULTS

Sixty-seven percent of women reported UPSI at last intercourse. UPSI was independently associated with heavy sporadic drinking [odds ratio (OR) 2.8, 95% CI 1.2-6.6] and having been pregnant (OR 2.25, 95% CI 1.1-4.6).

CONCLUSIONS

Despite the high risk for HIV acquisition or transmission and unintended pregnancy, condom use among the study population is low. Programmes to investigate and improve contraceptive use, including condom use, among this vulnerable group of women are needed. Such programmes may require identifying and targeting female reproductive health concerns and problem drinking, particularly heavy sporadic drinking, rather than conventional measures of alcohol misuse.

Identification of germline mutations in the cancer predisposing gene CDH1 in patients with orofacial clefts

Orofacial clefts (OFC) are among the most common birth defects worldwide. The etiology of non-syndromic OFC is still largely unknown. During embryonic development, the cell adhesion molecule E-cadherin, encoded by CDH1, is highly expressed in the median edge epithelium of the palate. Furthermore, in multiple families with CDH1 mutations, OFC cases are observed. To determine whether CDH1 is a causative gene for non-syndromic OFC and to assess whether CDH1 mutation screening in non-syndromic OFC patients enables identification of families at risk of cancer, direct sequencing of the full coding sequence of CDH1 was performed in a cohort of 81 children with non-syndromic OFC. Eleven children had heterozygous CDH1 sequence variants, 5 cases with 4 distinct missense mutations and 8 cases with 4 intronic variants. Using a combination of in silico predictions and in vitro functional assays, three missense mutations in four non-syndromic OFC patients were predicted to be damaging to E-cadherin protein function. The intronic variants including one tested in an in vitro assay appeared to be benign, showing no influence on splicing. Functionally relevant heterozygous CDH1 missense mutations were found in 4 out of 81 (5%) patients with non-syndromic OFC. This finding opens a new pathway to reveal the molecular basis of non-syndromic OFC. Cancer risk among carriers of these mutations needs to be defined.

Roles of BMP signaling pathway in lip and palate development

Cleft lip with or without cleft palate (CLP) and cleft palate only (CP) are severe disruptions affecting orofacial structures. Patients with orofacial clefts require complex interdisciplinary care, which includes nursing, plastic surgery, maxillofacial surgery, otolaryngology, speech therapy, audiology, psychological and genetic counseling, orthodontics and dental treatment, among others. Overall, treatment of clefts of the lip and palate entails a significant economic burden for families and society. Therefore, prevention is the ultimate objective and this will be facilitated by a complete understanding of the etiology of this condition. Here we review the current concepts regarding the genetic and environmental factors contributing to orofacial clefts and emphasize on the roles of BMP signaling pathway components in the normal and aberrant development of the lip and palate.

Genetic basis of susceptibility to teratogen induced birth defects

Birth defects remain the leading cause of infant death in US. The field of teratology has been focused on the causes and underlying mechanisms of birth defects for decades, yet our understanding of these critical issues remain unacceptably vague. Conclusions from years of animal and human studies made it clear that the vast majority of birth defects have multifactorial origins, with contributions from environmental and genetic factors. The environment comprises not only of the physical, biological, and chemical external environment surrounding the pregnant woman, but it also includes the internal environment of the woman's body that interact with the developing embryo in a complex fashion. The importance of maternal and embryonic genetic factors consisting of countless genetic variants/mutations that exist within every individual contribute to birth defect susceptibility is only now being more fully appreciated. This great complexity of the genome and its diversity within individuals and populations seems to be the principal reason why the same teratogenic exposure can induce severe malformation in one embryo, while fail to do so to other exposed embryos. As the interaction between genetic and environmental factors has long been recognized as the first "Principle of Teratology" by Wilson and Warkany [1965. Teratology: Principles and techniques. Chicago: University of Chicago Press], it is only recently that the appropriate investigative tools have been developed with which to fully investigate this fundamental principle. The introduction of high throughput technologies like whole genome sequencing or genome-wide association studies are promising to deliver an enormous amount of new data that will shed light on the genomic factors that contribute susceptibility to environmental teratogens. In this review, we attempt to summarize the epidemiological and experimental literature concerning birth defects whose phenotypic expression can be clearly related to the interactions between several select environmental factors and those genetic pathways in which they are most likely to have significant modifying effects. © 2011 Wiley-Liss, Inc.

Strain-specific vulnerability to alcohol exposure in utero via hippocampal parent-of-origin expression of deiodinase-III

Prenatal exposure to alcohol is thought to be the most prevalent nongenetic cause of a wide range of neurodevelopmental deficits. Insufficient thyroid hormone levels are one mechanism that hampers development of the alcohol-exposed brain, and we hypothesized that altered dosage of the imprinted thyroid hormone-inactivating gene deiodinase-III (Dio3) is responsible. To follow parent-of-origin allelic expression of Dio3 in the fetal and adult offspring of alcohol-consuming and control dams, we reciprocally crossed 2 polymorphic rat strains. In the frontal cortex, prenatal alcohol exposure altered imprinting patterns and total expression of Dio3 in the fetus and produced a permanent hypothyroid milieu in the adult. In the hippocampus, alcohol affected the paternal and total expression of Dio3 in the fetus and in the adult male, where thyroid hormone levels were concomitantly increased. Hippocampus-dependent behavioral deficits were identified exclusively in males, suggesting they are dependent on aberrant allelic Dio3 expression. None of these effects were observed in offspring of the reciprocal cross. Thus, genetic background and sex modify vulnerability to prenatal alcohol via brain region-specific expression of Dio3. This finding implies that phenotypic heterogeneity in human fetal alcohol spectrum disorder can be linked to genetic vulnerability in affected brain regions.

Genetics of nonsyndromic orofacial clefts

With an average worldwide prevalence of approximately 1.2/1000 live births, orofacial clefts are the most common craniofacial birth defects in humans. Like other complex disorders, these birth defects are thought to result from the complex interplay of multiple genes and environmental factors. Significant progress in the identification of underlying genes and pathways has benefited from large populations available for study, increased international collaboration, rapid advances in genotyping technology, and major improvements in analytic approaches. Here we review recent advances in genetic epidemiological approaches to complex traits and their applications to studies of nonsyndromic orofacial clefts. Our main aim is to bring together a discussion of new and previously identified candidate genes to create a more cohesive picture of interacting pathways that shape the human craniofacial region. In future directions, we highlight the need to search for copy number variants that affect gene dosage and rare variants that are possibly associated with a higher disease penetrance. In addition, sequencing of protein-coding regions in candidate genes and screening for genetic variation in noncoding regulatory elements will help advance this important area of research.