The MSX1 allele 4 homozygous child exposed to smoking at periconception is most sensitive in developing nonsyndromic 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.

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.

Msx1 Heterozygosity in Mice Enhances Susceptibility to Phenytoin-Induced Hypoxic Stress Causing Cleft Palate

OBJECTIVE

Cleft palate is among the most frequent congenital defects in humans. While gene-environment multifactorial threshold models have been proposed to explain this cleft palate formation, only a few experimental models have verified this theory. This study aimed to clarify whether gene-environment interaction can cause cleft palate through a combination of specific genetic and environmental factors.

METHODS

Msx1 heterozygosity in mice (Msx1^+/-) was selected as a genetic factor since human MSX1 gene mutations may cause nonsyndromic cleft palate. As an environmental factor, hypoxic stress was induced in pregnant mice by administration of the antiepileptic drug phenytoin, a known arrhythmia inducer, during palatal development from embryonic day (E) 11 to E14. Embryos were dissected at E13 for histological analysis or at E17 for recording of the palatal state.

RESULTS

Phenytoin administration downregulated cell proliferation in palatal processes in both wild-type and Msx1^+/- embryos. Bone morphogenetic protein 4 (Bmp4) expression was slightly downregulated in the anterior palatal process of Msx1^+/- embryos. Although Msx1^+/- embryos do not show cleft palate under normal conditions, phenytoin administration induced a significantly higher incidence of cleft palate in Msx1^+/- embryos compared to wild-type littermates.

CONCLUSION

Our data suggest that cleft palate may occur because of the additive effects of Bmp4 downregulation as a result of Msx1 heterozygosity and decreased cell proliferation upon hypoxic stress. Human carriers of MSX1 mutations may have to take more precautions during pregnancy to avoid exposure to environmental risks.

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

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

Influence of Second-Hand Smoke and Prenatal Tobacco Smoke Exposure on Biomarkers, Genetics and Physiological Processes in Children-An Overview in Research Insights of the Last Few Years

Children are commonly exposed to second-hand smoke (SHS) in the domestic environment or inside vehicles of smokers. Unfortunately, prenatal tobacco smoke (PTS) exposure is still common, too. SHS is hazardous to the health of smokers and non-smokers, but especially to that of children. SHS and PTS increase the risk for children to develop cancers and can trigger or worsen asthma and allergies, modulate the immune status, and is harmful to lung, heart and blood vessels. Smoking during pregnancy can cause pregnancy complications and poor birth outcomes as well as changes in the development of the foetus. Lately, some of the molecular and genetic mechanisms that cause adverse health effects in children have been identified. In this review, some of the current insights are discussed. In this regard, it has been found in children that SHS and PTS exposure is associated with changes in levels of enzymes, hormones, and expression of genes, micro RNAs, and proteins. PTS and SHS exposure are major elicitors of mechanisms of oxidative stress. Genetic predisposition can compound the health effects of PTS and SHS exposure. Epigenetic effects might influence in utero gene expression and disease susceptibility. Hence, the limitation of domestic and public exposure to SHS as well as PTS exposure has to be in the focus of policymakers and the public in order to save the health of children at an early age. Global substantial smoke-free policies, health communication campaigns, and behavioural interventions are useful and should be mandatory.

The Primary Care Pediatrician and the Care of Children With Cleft Lip and/or Cleft Palate

Orofacial clefts, specifically cleft lip and/or cleft palate (CL/P), are among the most common congenital anomalies. CL/P vary in their location and severity and comprise 3 overarching groups: cleft lip (CL), cleft lip with cleft palate (CLP), and cleft palate alone (CP). CL/P may be associated with one of many syndromes that could further complicate a child's needs. Care of patients with CL/P spans prenatal diagnosis into adulthood. The appropriate timing and order of specific cleft-related care are important factors for optimizing outcomes; however, care should be individualized to meet the specific needs of each patient and family. Children with CL/P should receive their specialty cleft-related care from a multidisciplinary cleft or craniofacial team with sufficient patient and surgical volume to promote successful outcomes. The primary care pediatrician at the child's medical home has an essential role in making a timely diagnosis and referral; providing ongoing health care maintenance, anticipatory guidance, and acute care; and functioning as an advocate for the patient and a liaison between the family and the craniofacial/cleft team. This document provides background on CL/P and multidisciplinary team care, information about typical timing and order of cleft-related care, and recommendations for cleft/craniofacial teams and primary care pediatricians in the care of children with CL/P.

Maternal smoking during pregnancy and birth defects in children: a systematic review with meta-analysis

This systematic review aimed to investigate the association between maternal smoking during pregnancy and birth defects in children. We performed an electronic search of observational studies in the databases ovid MEDLINE (1950 to April 2010), LILACS and SciELO. We included 188 studies with a total of 13,564,914 participants (192,655 cases). Significant positive associations were found between maternal smoking and birth defects in the following body systems: cardiovascular (OR: 1.11; 95%CI: 1.03-1.19), digestive (OR: 1.18; 95%CI: 1.07-1.30), musculoskeletal (OR: 1.27; 95%CI: 1.16-1.39) and face and neck (OR: 1.28; 95%CI: 1.19-1.37). The strength of association between maternal smoking and birth defects measured by the OR (95%CI) is significantly related to the amount of cigarettes smoked daily (χ2 = 12.1; df = 2; p = 0.002). In conclusion, maternal smoking during pregnancy is associated with congenital malformations in children and this association is dose-dependent.

Nicotine Exposure During Pregnancy Results in Persistent Midline Epithelial Seam With Improper Palatal Fusion

INTRODUCTION

Nonsyndromic cleft palate is a common birth defect (1:700) with a complex etiology involving both genetic and environmental risk factors. Nicotine, a major teratogen present in tobacco products, was shown to cause alterations and delays in the developing fetus.

METHODS

To demonstrate the postpartum effects of nicotine on palatal development, we delivered three different doses of nicotine (1.5, 3.0, and 4.5mg/kg/d) and sterile saline (control) into pregnant BALB/c mice throughout their entire pregnancy using subcutaneous micro-osmotic pump. Dams were allowed to deliver (~day 21 of pregnancy) and neonatal assessments (weight, length, nicotine levels) were conducted, and palatal tissues were harvested for morphological and molecular analyses, as well as transcriptional profiling using microarrays.

RESULTS

Consistent administration of nicotine caused developmental retardation, still birth, low birth weight, and significant palatal size and shape abnormality and persistent midline epithelial seam in the pups. Through microarray analysis, we detected that 6232 genes were up-regulated and 6310 genes were down-regulated in nicotine-treated groups compared to the control. Moreover, 46% of the cleft palate-causing genes were found to be affected by nicotine exposure. Alterations of a subset of differentially expressed genes were illustrated with hierarchal clustering and a series of formal pathway analyses were performed using the bioinformatics tools.

CONCLUSIONS

We concluded that nicotine exposure during pregnancy interferes with normal growth and development of the fetus, as well results in persistent midline epithelial seam with type B and C patterns of palatal fusion.

IMPLICATIONS

Although there are several studies analyzing the genetic and environmental causes of palatal deformities, this study primarily shows the morphological and large-scale genomic outcomes of gestational nicotine exposure in neonatal mice palate.The previous version was incorrect. New authors Ali Nawshad, Hasan Otu, Janki Sharma, and Elizabeth Sheldon have been included in this version; the funding and acknowledgement sections have been updated accordingly; the article title, some text, and one supplementary data file have been edited; and the corresponding author has been changed. The original corresponding author regrets these earlier errors.

Higher risk of orofacial clefts in children born to mothers with angina pectoris: a population-based case-control study

Previously an unexpected association of maternal angina pectoris (MAP) during pregnancy with a higher risk of orofacial clefts in their children was found. There were three objectives of this study: (i) to evaluate the validity of MAP-diagnoses in the previous study and the recent history of mothers with MAP in a follow-up study; (ii) to estimate the prevalence of other congenital abnormalities in the offspring of mothers with MAP; and (iii) to analyze the possible effect of confounders for the risk of orofacial clefts. The large dataset of population-based Hungarian Case-Control Surveillance System of Congenital Abnormalities, 1980-1996 was evaluated including 22 843 cases with congenital abnormalities and 38 151 controls without any defect. Twenty-two cases (0.10%) and 12 controls (0.03%) were born to mothers with medically recorded MAP (odds ratio [OR] with 95% confidence interval [CI]: 3.7, 1.8-7.3). Of 22 cases, six had isolated cleft lip ± palate (OR with 95% CI: 13.3, 4.9-35.9) and two were affected with isolated cleft palate (OR with 95% CI: 10.5, 2.3-47.6). The diagnosis of MAP was confirmed in seven women visited at home in 2009-2010, two had recent myocardial infarction and five were smokers. There was no higher risk for other congenital abnormalities. In conclusion the higher risk of orofacial clefts was confirmed in the children of mothers with MAP and smoking may trigger the genetic predisposition of both MAP and orofacial clefts. However, the number of cases was limited and therefore further studies are needed to confirm or reject this theoretically and practically important observation.

Association of JARID2 polymorphisms with non-syndromic orofacial clefts in northern Chinese Han population

OBJECTIVES

Non-syndromic orofacial clefts (NSOC) are the most common human craniofacial malformation in all worldwide populations. Recently, the jumoji AT-rich interaction domain 2 (JARID2) had been reported to be a novel candidate gene for non-syndromic cleft lip with or without cleft palate (CL/P). The SNPs rs2076056, rs2237138 and rs2299043 in JARID2 were highly significant in Italian families.

MATERIAL AND METHODS

In the current research, a case-control study was conducted to examine the association between these three SNPs and NSOC in a northern Chinese Han population. Genotyping of the three SNPs were performed using SNaPshot minisequencing technique.

RESULTS

Distribution of rs2237138 genotypes in CL/P group was different from those in the control group (P = 0.04), but significant results did not persist after Benjamini and Hochberg false discovery rate (FDR) correction for multiple tests. Further logistic regression analysis showed that rs2237138 GG genotypes were associated with decreased CL/P susceptibility (OR = 0.34, 95% CI = 0.13-0.84), compared with the AA wild-type homozygote. For the haplotype CGT, a statistically difference was identified between the CL/P group and controls (P = 0.04). And carriers of GAT haplotype were considered to be less frequent among cleft palate only group as compared to controls (P = 0.02). However, both of the haplotypes association did not remain statistically significant after Benjamini and Hochberg FDR correction.

CONCLUSION

We got a weak association between these polymorphisms and NSOC in both single-marker and haplotype analyses. Our data further strengthen the conclusion that JARID2 polymorphisms are associated with NSOC susceptibility.

Classifying Common Oral Clefts: A New Approach after Descriptive Registration

Objective

Using the Dutch Oral Cleft Registration, which records the morphology and topography of common oral clefts, a new classification based on the (patho)embryology of the primary and secondary palates was tested.

Design

Prospective observational study.

Setting

The fifteen cleft palate teams in the Netherlands register patients to the national registry.

Patients

All unoperated patients with common oral clefts reported between 1997 and 2006 inclusive were included.

Main Outcome Measures

The classification is based on the pathoembryological events that ultimately result in various subphenotypes of common oral clefts. Patients within the three categories cleft lip/alveolus (CL/A), cleft lip/alveolus and palate (CL/AP), and cleft palate (CP) were divided into three subgroups: fusion defects, differentiation defects, and fusion and differentiation defects. A timetable was constructed to relate the type of clefting to the time of derailment during embryonic development.

Results

3512 patients were included. Patients with CL/A showed 22% fusion defects, 75% differentiation defects, and 3% fusion and differentiation defects. CL/AP patients and CP patients mostly showed fusion defects (70% and 89%, respectively). We were able to relate almost all (over 90%) cleft subphenotypes to specific weeks in embryonic development.

Conclusions

This classification provides new cleft subgroups that may be used for clinical and fundamental research. The subphenotypes of these subgroups originate from different time frames during embryonic development and different cell biological mechanisms, thereby enabling more accurate data for, e.g., gene identification and/or environmental factors.

Genome-wide analysis of parent-of-origin effects in non-syndromic orofacial clefts

Parent-of-origin (PofO) effects, such as imprinting are a phenomenon where the effect of variants depends on parental origin. Conventional association studies assume that phenotypic effects are independent of parental origin, and are thus severely underpowered to detect such non-Mendelian effects. Risk of orofacial clefts is influenced by genetic and environmental effects, the latter including maternal-specific factors such as perinatal smoking and folate intake. To identify variants showing PofO effects in orofacial clefts we have used a modification of the family-based transmission disequilibrium test to screen for biased transmission from mothers and fathers to affected offspring, biased ratios of maternal versus paternal transmission, and biased frequencies of reciprocal classes of heterozygotes among offspring. We applied these methods to analyze published genome-wide single-nucleotide polymorphism (SNP) data from ∼2500 trios mainly of European and Asian ethnicity with non-syndromic orofacial clefts, followed by analysis of 64 candidate SNPs in a replication cohort of ∼1200 trios of European origin. In our combined analysis, we did not identify any SNPs achieving conventional genome-wide significance (P<5 × 10(-8)). However, we observed an overall excess of loci showing maternal versus paternal transmission bias (P=0.013), and identified two loci that showed nominally significant effects in the same direction in both the discovery and replication cohorts, raising the potential for PofO effects. These include a possible maternal-specific transmission bias associated with rs12543318 at 8q21.3, a locus identified in a recent meta-analysis of non-syndromic cleft (maternal-specific P=1.5 × 10(-7), paternal-specific P=0.17). Overall, we conclude from this analysis that there are subtle hints of PofO effects in orofacial clefting.

Evidence of gene-environment interaction for two genes on chromosome 4 and environmental tobacco smoke in controlling the risk of nonsyndromic cleft palate

Nonsyndromic cleft palate (CP) is one of the most common human birth defects and both genetic and environmental risk factors contribute to its etiology. We conducted a genome-wide association study (GWAS) using 550 CP case-parent trios ascertained in an international consortium. Stratified analysis among trios with different ancestries was performed to test for GxE interactions with common maternal exposures using conditional logistic regression models. While no single nucleotide polymorphism (SNP) achieved genome-wide significance when considered alone, markers in SLC2A9 and the neighboring WDR1 on chromosome 4p16.1 gave suggestive evidence of gene-environment interaction with environmental tobacco smoke (ETS) among 259 Asian trios when the models included a term for GxE interaction. Multiple SNPs in these two genes were associated with increased risk of nonsyndromic CP if the mother was exposed to ETS during the peri-conceptual period (3 months prior to conception through the first trimester). When maternal ETS was considered, fifteen of 135 SNPs mapping to SLC2A9 and 9 of 59 SNPs in WDR1 gave P values approaching genome-wide significance (10(-6)<P<10(-4)) in a test for GxETS interaction. SNPs rs3733585 and rs12508991 in SLC2A9 yielded P = 2.26×10(-7) in a test for GxETS interaction. SNPs rs6820756 and rs7699512 in WDR1 also yielded P = 1.79×10(-7) and P = 1.98×10(-7) in a 1 df test for GxE interaction. Although further replication studies are critical to confirming these findings, these results illustrate how genetic associations for nonsyndromic CP can be missed if potential GxE interaction is not taken into account, and this study suggest SLC2A9 and WDR1 should be considered as candidate genes for CP.

Rehabilitative treatment of cleft lip and palate: experience of the Hospital for Rehabilitation of Craniofacial Anomalies/USP (HRAC/USP)--Part 1: overall aspects

Cleft lip and palate is the most common among craniofacial malformations and causes several esthetic and functional implications that require rehabilitation. This paper aims to generally describe the several aspects related to this complex pathology and the treatment protocol used by the Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo (HRAC-USP) along 40 years of experience in the treatment of individuals with cleft lip and palate.

Maternal smoking in pregnancy and birth defects: a systematic review based on 173 687 malformed cases and 11.7 million controls

BACKGROUND

There is uncertainty over whether maternal smoking is associated with birth defects. We conducted the first ever comprehensive systematic review to establish which specific malformations are associated with smoking.

METHODS

Observational studies published 1959–2010 were identified (Medline), and included if they reported the odds ratio (OR) for having a non-chromosomal birth defect among women who smoked during pregnancy compared with non-smokers. ORs adjusted for potential confounders were extracted (e.g. maternal age and alcohol), otherwise unadjusted estimates were used. One hundred and seventy-two articles were used in the meta-analyses: a total of 173 687 malformed cases and 11 674 332 unaffected controls.

RESULTS

Significant positive associations with maternal smoking were found for: cardiovascular/heart defects [OR 1.09, 95% confidence interval (CI) 1.02–1.17]; musculoskeletal defects (OR 1.16, 95% CI 1.05–1.27); limb reduction defects (OR 1.26, 95% CI 1.15–1.39); missing/extra digits (OR 1.18, 95% CI 0.99–1.41); clubfoot (OR 1.28, 95% CI 1.10–1.47); craniosynostosis (OR 1.33, 95% CI 1.03–1.73); facial defects (OR 1.19, 95% CI 1.06–1.35); eye defects (OR 1.25, 95% CI 1.11–1.40); orofacial clefts (OR 1.28, 95% CI 1.20–1.36); gastrointestinal defects (OR 1.27, 95% CI 1.18–1.36); gastroschisis (OR 1.50, 95% CI 1.28–1.76); anal atresia (OR 1.20, 95% CI 1.06–1.36); hernia (OR 1.40, 95% CI 1.23–1.59); and undescended testes (OR 1.13, 95% CI 1.02–1.25). There was a reduced risk for hypospadias (OR 0.90, 95% CI 0.85–0.95) and skin defects (OR 0.82, 0.75–0.89). For all defects combined the OR was 1.01 (0.96–1.07), due to including defects with a reduced risk and those with no association (including chromosomal defects).

CONCLUSIONS

Birth defects that are positively associated with maternal smoking should now be included in public health educational materials to encourage more women to quit before or during pregnancy.

Genetic studies in the Nigerian population implicate an MSX1 mutation in complex oral facial clefting disorders

BACKGROUND

Orofacial clefts are the most common malformations of the head and neck, with a worldwide prevalence of 1 in 700 births. They are commonly divided into CL(P) and CP based on anatomic, genetic, and embryologic findings. A Nigerian craniofacial anomalies study (NigeriaCRAN) was set up in 2006 to investigate the role of gene-environment interaction in the origin of orofacial clefts in Nigeria.

SUBJECTS AND METHODS

DNA isolated from saliva from Nigerian probands was used for genotype association studies and direct sequencing of cleft candidate genes: MSX1 , IRF6 , FOXE1, FGFR1 , FGFR2 , BMP4 , MAFB, ABCA4 , PAX7, and VAX1 , and the chromosome 8q region.

RESULTS

A missense mutation A34G in MSX1 was observed in nine cases and four HapMap controls. No other apparent causative variations were identified. Deviation from Hardy Weinberg equilibrium (HWE) was observed in these cases (p = .00002). A significant difference was noted between the affected side for unilateral CL (p = .03) and bilateral clefts and between clefts on either side (p = .02). A significant gender difference was also observed for CP (p = .008).

CONCLUSIONS

Replication of a mutation previously implicated in other populations suggests a role for the MSX1 A34G variant in the development of CL(P).

Clinical and functional data implicate the Arg(151)Ser variant of MSX1 in familial hypodontia

Multiple previous reports confirm that several missense alleles of MSX1 exhibit Mendelian inheritance of an oligodontia phenotype (agenesis of more than six secondary teeth besides third molars). However, the extent to which missense MSX1 alleles contribute to common, multifactorial disorders is less certain. It is still not yet clear whether multiple non-synonomous MSX1-coding variants identified among patients with oral clefting are merely neutral polymorphisms or whether any of these might represent real mutations with mild effects. The present work steps toward resolving these issues for at least one MSX1 allele: R151S, previously identified in a single Japanese proband with unilateral cleft lip and palate. Candidate gene sequencing within a patient cohort demonstrating mild tooth agenesis (loss of six or less secondary teeth besides third molars, hypodontia), secondarily identified this same MSX1 variant, functioning as a mildly deleterious, moderately penetrant allele. Four of five heterozygous R151S individuals from one Japanese family exhibited the hypodontia phenotype. The in vitro functional assays of the variant protein display partial repression activity with normal nuclear localization. These data establish that the MSX1-R151S allele is a low-frequency, mildly deleterious allele for familial hypodontia that alone is insufficient to cause oral facial clefting. Yet, as this work also establishes its hypomorphic nature, it suggests that it may in fact contribute to the likelihood of common birth disorder phenotypes, such as partial tooth agenesis and oral facial clefting. Nevertheless, the exact mechanism in which differential pleiotropy is manifested will need further and deeper clinical and functional analyses.

No evidence of HAND2 involvement in nonsyndromic cleft lip with or without cleft palate

Craniofacial morphogenesis is determined by multistep processes involving signalling molecules and transcription factors, which are organised into highly coordinated pathways. Derailment from this intricate network can lead to congenital malformations. Cells migrate from neural crests to populate different structures, such as branchial arches, involved in embryonal orofacial development. The EDN1 pathway is involved in branchial arch development. Gene knockout and knockdown experiments on EDN1 or its downstream effector dHAND resulted in mice that were characterised by craniofacial defects and cleft palate. Our aim was to evaluate whether the transcription factor HAND2 could be implicated in non-syndromic cleft lip with or without cleft palate (CL/P) aetiology. A sample study composed of 39 multiplex Italian pedigrees was enrolled to test linkage between two microsatellite flanking HAND2 locus and CL/P. No evidence of linkage between HAND2 and CL/P was obtained. Indeed, formal levels of exclusion were obtained with different inheritance models. Investigation results did not support a role of HAND2 in CL/P aetiology. Nevertheless a minor contribute of the gene in clefting could not be ruled out.

IRF6 polymorphisms are associated with nonsyndromic orofacial clefts in a Chinese Han population

IRF6 plays an important role in orofacial development. In the present study, we genotyped two polymorphisms (rs642961 and rs2235371) within the IRF6 locus and estimated their associations with risk of nonsyndromic orofacial clefts (NSOC), including the subgroups, in a hospital-based case-control study in a Chinese Han population. In the single locus analyses, we found rs642961 AG and AG/AA genotypes were associated with increased risk of NSOC, especially cleft lip with or without cleft palate (CL/P) and cleft lip with cleft palate (CLP), while significantly decreased risks were associated with rs2235371 CT and CT/TT genotypes. When examining the combined effects of these two polymorphisms and using the rs642961 A and rs2235371 C alleles as the risk alleles, we found genotypes containing 2-4 risk alleles conferred high risk to NSOC, CL/P, and CLP. Furthermore, to test whether rs642961 could modulate IRF6 expression in vivo, we surgically collected lip skin tissues within the adjacent region of lip cleft site and found rs642961 genotypes were associated with differential levels of IRF6 mRNA and protein expression in an allele-dosage manner, providing the first evidence that rs642961 affected IRF6 expression in vivo. Taken together, these findings confirm the contribution of IRF6 genetic variants in the etiology of NSOC in a Chinese Han population.

Validation of the NVSCA Registry for Common Oral Clefts: Study Design and First Results

Objective

Since 1997 the Dutch Association for Cleft Palate and Craniofacial Anomalies (NVSCA) has maintained a national registry of congenital craniofacial anomalies. This study validates data on three common oral cleft categories (cleft lip/alveolus = CL/A; cleft lip/alveolus and palate = CL/AP; and cleft palate = CP) and general items.

Design

Retrospective observational study.

Setting

All 15 Dutch cleft palate teams registered presurgery patients with common oral clefts (n = 2553) from 1997 to 2003.

Patients

A random sample of 250 cases was used; 13 cases were excluded.

Main Outcome Measures

The corresponding medical data were reviewed; these medical data served to validate the NVSCA registry data. Prevalence comparisons, 2 × 2 tables and validity measures were performed.

Results

The cleft categories most accurately recorded were CL/A and CP. Both categories had an observed agreement of 98%, kappa of 0.94, and a sensitivity and specificity of 97%. Cleft lip/alveolus and palate had an observed agreement of 95%, kappa of 0.89, a sensitivity of 90%, and a specificity of 99%. Regarding the general items, observed agreement and kappa were highest for adoption/foster child (99%; 0.76) and lowest for remarks about pregnancy (63%; 0.20). Sensitivity ranged from 25% (consanguinity) to 97% (white mother) and specificity was high for all items (93%) except for white father and mother (approximately 35%).

Conclusions

The NVSCA registry is a valuable tool for quality improvement and research because validity on all three common oral cleft categories is very good. Validity on the general items is reasonable to satisfying and appears to be related to the type of information.

Evidence of gene-environment interaction for the IRF6 gene and maternal multivitamin supplementation in controlling the risk of cleft lip with/without cleft palate

Although multiple genes have been identified as genetic risk factors for isolated, non-syndromic cleft lip with/without cleft palate (CL/P), a complex and heterogeneous birth defect, interferon regulatory factor 6 gene (IRF6) is one of the best documented genetic risk factors. In this study, we tested for association between markers in IRF6 and CL/P in 326 Chinese case-parent trios, considering gene-environment interaction for two common maternal exposures, and parent-of-origin effects. CL/P case-parent trios from three sites in mainland China and Taiwan were genotyped for 22 single nucleotide polymorphisms (SNPs) in IRF6. The transmission disequilibrium test was used to test for marginal effects of individual SNPs. We used PBAT to screen the SNPs and haplotypes for gene-environment (G×E) interaction and conditional logistic regression models to quantify effect sizes for SNP-environment interaction. After Bonferroni correction, 14 SNPs showed statistically significant association with CL/P. Evidence of G×E interaction was found for both maternal exposures, multivitamin supplementation and environmental tobacco smoke (ETS). Two SNPs showed evidence of interaction with multivitamin supplementation in conditional logistic regression models (rs2076153 nominal P=0.019, rs17015218 nominal P=0.012). In addition, rs1044516 yielded evidence for interaction with maternal ETS (nominal P=0.041). Haplotype analysis using PBAT also suggested interaction between SNPs in IRF6 and both multivitamin supplementation and ETS. However, no evidence for maternal genotypic effects or significant parent-of-origin effects was seen in these data. These results suggest IRF6 gene may influence risk of CL/P through interaction with multivitamin supplementation and ETS in the Chinese population.

A possible association of periodontal infectious diseases in pregnant women with isolated orofacial clefts in their children: A population-based case-control study

BACKGROUND

The aim of the study was to check the association of maternal periodontal infectious disease (MPID) during pregnancy and the possible risk for birth outcomes, mainly structural birth defects: congenital abnormalities (CAs) in their children.

METHODS

The population-based data set of the Hungarian Case-Control Surveillance System of Congenital Abnormalities, 1980-1996, was evaluated. The occurrence of medically recorded MPID in the prenatal maternity logbook was compared in 22,843 cases with different CAs and 38,151 matched controls without defects.

RESULTS

Twenty-one case mothers who had offspring with a CA (case group) and 17 pregnant women who delivered newborn infants without a CA (control group) had an MPID. However, of 21 cases, 6 had isolated cleft lip +/- palate (OR with 95% CI: 10.7, 4.2-27.3), and 2 were affected with isolated cleft palate (7.9, 1.8-34.2). Of these 8 cases, 6 had mothers with the exposure of MPID in the critical period of these orofacial clefts, 7 mothers were visited at home, and 6 were smokers during pregnancy.

CONCLUSIONS

The unexpected findings of the study showed a strong association of MPID during pregnancy with a higher risk of isolated orofacial clefts in their children.