A Study on Environmental Factors for Nonsyndromic Cleft Lip and/or Palate

Awareness, Knowledge, and Attitude Assessment of Cleft Lip With or Without Palate Management Among Vietnamese Dental and Medical Students: A Cross-Sectional Study

Background Cleft lip and/or palate (CL/P) are congenital malformations that require multidisciplinary treatment and in-depth knowledge for effective management, especially in countries like Vietnam, where the incidence rate is 1.4 per 1,000 live births. This study aimed to develop and validate a questionnaire to assess the awareness, knowledge, and attitudes of undergraduate medical and dental students at Hanoi Medical University, Vietnam, regarding CL/P management. Materials and methods The questionnaire was administered using Google Forms (Google LLC, USA). The study participants were 284 (55.6%) dental students and 227 (44.4%) medical students at Hanoi Medical University, Vietnam. The questionnaire comprised four sections: general information, awareness, knowledge, and attitude assessments. Results In the awareness assessment, 97.5% of students were aware of CL/P. However, 84.1% and 66.5% of medical and dental students, respectively, lacked confidence in their current knowledge. Confidence levels increased gradually from third-year to final-year students. Regarding etiology, most students believed genetic factors were the primary cause of CL/P, followed by environmental factors. The most commonly chosen treatment methods were oral, maxillofacial, and plastic surgeries. Dental students showed more interest in CL/P and felt a greater need for additional training in CL/P treatment and management than medical students. Both dental and medical students favored early intervention. However, 19.4% of students were unsure about the optimal time to begin treatment, with this uncertainty being more prevalent among medical students (26%) than among dental students (14.1%) (p<0.001). Conclusion This study emphasizes the need for improved education among undergraduate students, especially medical students, to improve CL/P management.

Parental Smoking and the Risk of Birth Defects in Offspring in China: A Systematic Review and meta-Analysis

OBJECTIVE

A meta-analysis of case-control studies was conducted to assess the risk of birth defects in offspring in China associated with maternal active and passive smoking and paternal smoking.

METHODS

Four electronic databases were searched for qualified research up to December 2023. A Random-effect model or fixed-effect model was used to calculate the overall comprehensive risk estimates; and the relationship between parental smoking and the risk of birth defects in different periods of pregnancy. Subgroup and sensitivity analyses were performed to explore possible sources of heterogeneity.

RESULTS

Sixty-two qualified studies involving 137,574 cases and 8,770,837 controls were included. Overall, maternal active smoking (OR = 2.19; 95% confidence interval (CI): 1.72-2.79; p < 0.01) and passive smoking (OR = 2.59,95% CI: 2.24-2.99; p < 0.01) as well as paternal active smoking (OR = 1.47,95% CI: 1.34-1.62; p < 0.01) were significantly associated with birth defect risk. The sources of heterogeneity were explored by subgroup analysis. Subgroup analysis showed that the risk of congenital heart disease in offspring was increased in paternal and maternal active smoking (OR = 2.97, 95% CI: 2.01-4.39; OR = 1.51, 95% CI: 1.30-1.74), respectively. Sensitivity analysis yielded consistent results.

CONCLUSION

Maternal active and passive smoking and paternal active smoking are risk factors for birth defects in offspring. Parents should be encouraged to quit smoking during the perinatal period and pregnancy.

An intercontinental comparison of the influence of smoking on the occurrence of nonsyndromic cleft lip and palate: a meta-analysis and systematic review

BACKGROUND

The influence of smoking on nonsyndromic clefts has been a topic of research for many years. However, few studies have investigated the effect of smoking on causing clefts in different gene pools.

METHODS

A meta-analysis was conducted of case-control studies related to smoking. Keywords such as "clefts," "cleft lip," "cleft palate," "orofacial cleft," and "smoking" were used to search the MEDLINE, Embase, and Cochrane databases.

RESULTS

In total, 51 articles were reviewed. The RevMan software was utilized for the analysis, and the Mantel-Haenszel method was employed to pool the odds ratios (ORs) and 95% confidence intervals. Although the overall OR, a measure of the association between exposure and outcome, was higher for smokers than for non-smokers, this association was significantly stronger in individuals from Asia and South America (1.73), and lowest in Europe (1.31). Among active and passive smokers in Asia, the OR was approximately 0.93, indicating an equivalent impact from both types of smoking.

CONCLUSION

This analysis indirectly suggests that restriction measures targeting both active and passive smoking are crucial in Asia.

Characteristics of Factors Influencing the Occurrence of Cleft Lip and/or Palate: A Case Analysis and Literature Review

INTRODUCTION

Cleft lip with or without cleft palate (CL/P) stands as the most common congenital facial anomaly, stemming from multifactorial causes.

OBJECTIVE

Our study aimed to ascertain the prevalence and characteristics of cleft palates, identify associated risk factors to inform prevention and prenatal detection for early intervention, and assess postoperative rehabilitation protocols for cleft palates.

DESIGN

This study employs a retrospective descriptive and clinical approach.

PATIENTS

The study includes 103 children with cleft palates treated at the Department of Head and Neck Surgery Clinic for Children and Young Adults, Department of Clinical Pediatrics, University of Warmia and Mazury.

METHODS

We conducted a thorough evaluation of records, considering variables such as sex, cleft type, maternal occupation, parental education, and family history of clefts. Data analysis was carried out using R software version GPL-3 and ordinal logistic regression analyses.

RESULTS

Notably, children born to mothers who experienced significant stress during pregnancy exhibited a 9.4-fold increase in the odds of having bilateral cleft palates. Conversely, no substantial evidence was found to support the influence of the child's sex, birth order, body mass, maternal exposure to workplace toxins, infections, or drug toxicity on the dependent variable.

CONCLUSIONS

Our findings suggest that children with parents who have a history of clefts and those with less educated mothers are more likely to develop bilateral cleft palates. Additionally, children born to mothers experiencing stress during pregnancy face an increased risk of bilateral cleft palates. It is important to note that there is a paucity of literature on rehabilitation following various cleft palate surgical techniques in children.

Oral Cleft and Maternal History of Spontaneous Abortion: A Case-Control Study

To investigate and compare the occurrence of previous spontaneous abortion among mothers of children with nonsyndromic oral clefts (NSOC) and mothers of children without NSOC; to understand if previous spontaneous abortion could be a risk factor for the occurrence of NSOC in subsequent pregnancies.

Case-control study.

Nonsyndromic oral clefts is an important public health problem. In the context of investigating risk factors for the occurrence of this malformation, previous spontaneous abortion have been considered in the etiology at NSOC.

There were 1004 participants. In the case group 502 mothers of children with NSOC, and in the control group 502 mothers of children without NSOC or any other malformation or syndrome.

A standardized questionnaire was utilized to interview the maternal history of spontaneous abortion.

The data were evaluated using descriptive statistics, and comparisons were performed using the Chi-square test, adopting a significance level of 5%.

The prevalence of maternal history of spontaneous abortion was 16.3% in the case group and 15.9% in the control group. Comparing the groups there was no statistical difference (p-value = 0.93). Analyzing the occurrence of previous spontaneous abortion, separating the case group according to the type of cleft in the child, no statistical differences were observed when comparing these groups between them.

Maternal history of spontaneous abortion was not associated with NSOC, not representing an independent risk factor for NSOC in the Brazilian population.

Genetic Inheritance Models of Non-Syndromic Cleft Lip with or without Palate: From Monogenic to Polygenic

Non-syndromic cleft lip with or without palate (NSCL/P) is a prevalent birth defect that affects 1/500-1/1400 live births globally. The genetic basis of NSCL/P is intricate and involves both genetic and environmental factors. In the past few years, various genetic inheritance models have been proposed to elucidate the underlying mechanisms of NSCL/P. These models range from simple monogenic inheritance to more complex polygenic inheritance. Here, we present a comprehensive overview of the genetic inheritance model of NSCL/P exemplified by representative genes and regions from both monogenic and polygenic perspectives. We also summarize existing association studies and corresponding loci of NSCL/P within the Chinese population and highlight the potential of utilizing polygenic risk scores for risk stratification of NSCL/P. The potential application of polygenic models offers promising avenues for improved risk assessment and personalized approaches in the prevention and management of NSCL/P individuals.

Predisposing factors of non-syndromic cleft lip and cleft palate in the northern Thai population: A 10-year retrospective case-control study

The most common congenital anomaly is orofacial cleft, which is categorized into two main types: cleft lip with or without cleft palate (CL/P) and cleft palate only (CPO). One of the most accepted etiologies is multifactorial (gene-environment). This study aimed to identify the amendable risk factors of an orofacial cleft in Northern Thailand. A retrospective case-control study in Maharaj Nakorn Chiang Mai Hospital was conducted from 2011 to 2020. One hundred and seventeen cases of CL/P and CPO were included. Forty-nine normal children were enrolled in a time-matched control group. Exploratory survey data on maternal exposures were collected. Multivariate logistic regression was used to estimate the adjusted association between maternal exposures and CL/P, and CPO occurrence. Multivariate analysis identified three predisposing factors that increased the risk of CL/P and CPO. The first factor was caffeine consumption with a total amount of 560 mg/week (adjusted OR: 7.59; 95% CI: 2.48-23.23; p < 0.001). The second factor was any smoker or passive smoking (adjusted OR: 8.47; 95% CI: 1.63-43.92; p = 0.011). The third factor was a low socioeconomic status (income of lower than 270 USD/month; adjusted OR: 4.05; 95% CI: 1.07-15.27; p = 0.039). From the 10-year study in Northern Thailand: caffeine consumption, exposure to cigarette smoke, and low socioeconomic status were identified as associated negative factors for orofacial clefts. We propose that preconceptional counseling for risk reduction should be emphasized in reducing the mother's exposure to these factors. Future investigations in large multicenter populations are suggested.

COVID-19 related risk factors and their association with non-syndromic orofacial clefts in five Arab countries: a case-control study

BACKGROUND

The environmental etiology of non-syndromic orofacial clefts (NSOFCs) is still under research. The aim of this case-control study is to assess COVID-19 associated factors that may be related to the risk of NSOFC in five Arab countries. These factors include COVID-19 infection, COVID-19 symptoms, family member or friends infected with COVID-19, stress, smoking, socioeconomic status and fear of COVID-19.

METHODS

The study took place in governmental hospitals in five Arab countries from November 2020 to November 2021. Controls are matched in the month of delivery and site of recruitment. A clinical examination was carried out using LASHAL classification. Maternal exposure to medication, illnesses, supplementation, COVID-19 infection during their pregestation and 1st trimester periods were evaluated using a validated questionnaire. Maternal exposure to stress was assessed using the Life Events scale, fear of covid-19 scale, family member or friend affected with covid-19 infection, pregnancy planning and threatened abortion.

RESULTS

The study recruited 1135 infants (386 NSOFC and 749 controls). Living in urban areas, maternal exposure to medications 3-months pregestation, maternal exposure to any of the prenatal life events and maternal fear of COVID-19 significantly increased the risk of having a child with NSOFC. On the other hand, mothers exposed to supplementation 3-months pregestation, mothers suspected of having COVID-19 infection, family members or friends testing positive with COVID-19 significantly decreased the risk of having a child with NSOFC.

CONCLUSIONS

This study suggests that NSOFC may be associated with maternal exposure to lifetime stress and COVID-19 fear in particular, with no direct effect of the COVID-19 infection itself. This highlights the importance of providing psychological support for expecting mothers during stressful events that affect populations such as the COVID-19 pandemic, in addition to the usual antenatal care.

Maternal Common Cold or Fever During Pregnancy and the Risk of Orofacial Clefts in the Offspring: A Systematic Review and Meta-analysis

The common cold and/or an associated fever during pregnancy have/has been suspected to harm the developing fetus. We sought possible correlations between a maternal common cold or fever during pregnancy and the risk of orofacial clefts in the offspring.

We systematically searched PubMed and Embase using appropriate keywords, and we checked the reference lists of retrieved articles. We used random-effects models to estimate overall relative risks.

Incidence of orofacial clefts.

We included 13 case-control studies. Modest but statistically significant associations were found between a maternal common cold and cleft lip with or without a cleft palate (CL/CP) (odds ratio [OR] 2.17; 95% confidence interval [CI] 1.66-2.83) and a cleft palate only (CPO) (OR 3.08; 95% CI 1.5-6.34). Furthermore, maternal fever was also associated with an increased risk of CL/CP (OR 1.91, 95% CI 1.3-2.8) and CPO (OR 1.48, 95% CI 0.83-2.63) in the offspring. Further analyses of maternal influenza (alone) yielded similar results.

Although evidence of heterogeneity should be carefully evaluated, our findings suggest that maternal common cold or fever during pregnancy may be associated with a greater risk of CL/CP or CPO in the offspring. Future cohort studies using valid assessments of maternal common cold exposure during pregnancy that consider the severity of fever are needed to clarify the contribution of maternal common cold or fever status to the risk of orofacial clefts in children.

Maternal stress as a risk factor for non-syndromic orofacial clefts: Systematic review and meta-analysis

Background

Non-syndromic orofacial clefts (NSOFC) are among the most common congenital malformations. Several studies have investigated the association between stress and NSOFC; however, they have reported different and heterogeneous results. Therefore, this systematic review was conducted to investigate the association between maternal periconceptional stress and non-syndromic orofacial clefts in infants.The research question was "Is maternal periconceptional stress an etiological factor for non-syndromic orofacial clefts in infants"?

Methods

Search strategy, inclusion/exclusion criteria, and data extraction from studies reporting periconceptional maternal exposure to stress and NSOFC were implemented without language restrictions. The risks of bias in the identified studies was assessed, and this information was used in the sensitivity analyses to explain heterogeneity. A meta-analysis of the extracted data was performed.

Results

Twelve eligible studies were included. Forest plot for meta-analysis of the association between maternal periconceptional exposure to stress and NSOFC among studies with adjustment for potential confounders showed a statistically significant association with an increased risk of NSOFC (odds ratio [OR]:1.17; P = 0.03), which was apparent for both cleft lip with and without palate (OR:2.07; P = 0.007) and cleft palate (OR:1.72; P = 0.003). There was a substantial heterogeneity between studies, which improved when analyzing only studies that were adjusted for potential confounders.

Conclusion

Based on the currently available evidence, maternal exposure to periconceptional stress could be considered a risk factor for NSOFCs. Therefore, we strongly recommend research investigating the effect of stress caused by the coronavirus disease-2019 pandemic on the incidence of clefts.

Maternal Cigarette Smoking and Cleft Lip and Palate: A Systematic Review and Meta-Analysis

A systematic review and meta-analysis to determine the association between active maternal smoking and cleft lip and palate etiology.

Medline, Embase, Web of Science and the Cochrane Library from inception to November, 2020.

Observational studies of cigarette smoking habits in pregnant women. Outcomes included cleft lip and/or palate, cleft lip  ±  palate and cleft palate only.

Publication bias analyses were performed and the Newcastle Ottawa scales were used to assess study quality. Fixed or random effect models were used in the meta-analysis, dependent on risk of statistical heterogeneity.

Forty-five studies were eligible for inclusion of which 11 were cohort and 34 were case-control studies. Sixteen studies were of sufficient standard for inclusion in the meta-analysis. The summary odds ratio for the association between smoking and cleft lip and/or palate was 1.42 (95%CI 1.27-1.59) with a population attributable fraction of 4% (95%CI 3%-5%). There was limited evidence to show a dose-response effect of smoking.

This review reports a moderate association between maternal smoking and orofacial cleft but the overall quality of the conventional observational studies included was poor. There is a need for high quality and novel research strategies to further define the role of smoking in the etiology of cleft lip and palate.

The genetic factors contributing to the risk of cleft lip-cleft palate and their clinical utility

Cleft lip and cleft palate (CL/P) are among the most common congenital malformations in neonates and have syndromic or nonsyndromic forms. Nonsyndromic forms of malformation are being reported to be associated with chromosomal DNA modification by teratogenic exposure and to complex genetic contributions of multiple genes. Syndromic forms are shown to be related to chromosomal aberrations or monogenic diseases. There is a growing body of data illustrating the association of several genes with risk of developing this malformation, including genetic defects in T-box transcription factor-22 (TBX22), interferon regulatory factor-6 (IRF6), and poliovirus receptor-like-1 (PVRL1), responsible for X-linked cleft palate, cleft lip/palate-ectodermal dysplasia syndrome, and Van der Woude and popliteal pterygium syndromes, respectively. Genetic variants in MTR, PCYT1A, ASS1, SLC 25A13, GSTM1, GSTT1, SUMO1 BHMT1, and BHMT2 are being reported to be linked with CL/P risk. The etiology of nonsyndromic CLP is still remained to be unknown, although mutations in candidate genes have been found. Here, we provide an overview about the potential variants to be associated with CL/P for identification of the relative risk of CLP with respect to the basis of genetic background and environmental factors (e.g., dietary factors, alcohol use).

Clinical and Descriptive Study of Orofacial Clefts in Colombia: 2069 Patients From Operation Smile Foundation

OBJECTIVE

To describe the population of patients with cleft lip and/or palate (CL/P) in terms of cleft phenotypes, gender, age, ethnic group, family history, clinical presentation (syndromic vs nonsyndromic), some environmental and behavioral factors, and some clinical features.

DESIGN

Descriptive retrospective study.

SETTING

Patients attending the genetics counseling practice in Operation Smile Foundation, Bogotá, Colombia, for over 8 years.

PARTICIPANTS

No screening was conducted. All patients requiring clinical genetics assessment in Operation Smile Foundation were included in the study.

RESULTS

Left cleft lip and palate (CLP) and nonsyndromic forms were the most frequent types of malformations in this population. Psychomotor retardation and heart disease were the most frequent comorbidities in these patients. A low proportion of mothers exposed to passive smoking during pregnancy was observed and low birth weight accounted for an important number of cases. Aarskog, velocardiofacial, and orofaciodigital syndromes were the most frequent syndromic forms of CLP in this population.

CONCLUSIONS

In this study, the most frequent type of CL/P was the nonsyndromic complete left CLP. Aarskog, velocardiofacial, and orofaciodigital syndromes were the most frequent syndromic forms of CL/P in this population.

Maternal genotypes of folate/one-carbon metabolism gene variants and nonsyndromic cleft lip with or without cleft palate risk in Chile

The aim of this study was to evaluate, in a case-control design, the association between maternal genotypes for variants in 23 genes involved in folate/one-carbon metabolism and nonsyndromic cleft lip with or without cleft palate (NSCL/P) in a Chilean population. After applying several filters to an Illumina array, we extracted 175 single nucleotide polymorphisms (SNPs) from 150 mothers of NSCL/P cases and 150 control women. Association was evaluated using computed odds ratio (OR) with a 95% confidence interval (95% CI) in additive, recessive, and dominant models. After multiple comparison correction, only SNP rs4451422 (A>C), located 237 bp downstream of the gene encoding the human folylpolyglutamate synthetase (FPGS), maintained a significant association with NSCL/P in the offspring (OR 3.03; 95% CI 1.69-5.26). The variant rs4451422 is associated with a decrease in FPGS expression according to database annotation. Our results lead to a new hypothesis that a lower activity of FPGS enzyme reduces intracellular folate levels and increases the risk of an offspring having NSCL/P.

Family history in non-syndromic orofacial clefts: Is there a pattern?

OBJECTIVE

To survey the frequency and pattern of family history for non-syndromic orofacial clefts (NSOFC). Initial hypothesis: more complex forms have a higher frequency of positive family history.

MATERIALS AND METHODS

A retrospective study was carried with 2,668 subjects with three different types of clefts (CL Group (cleft lip), CLP Group (cleft lip and palate), and CP group (cleft palate)); family history information was collected. The Chi-square (X² ) and Z-test were used.

RESULTS

A positive family history was found in 31% of the sample. The CLP Group had highest percentage and highest proportion of affected relatives, being these factors statistically significant when compared to the CP Group. Comparisons between the CLP Male and CL Male with CP Male were statistically significant. First-degree kinship was the most frequently found.

CONCLUSIONS

The initial hypothesis was confirmed, subjects with CLP had the highest percentage of positive family history, the highest proportion of affected relatives and had more affected relatives in comparison with CP. It is more common to find affected relatives in the CLP Male and CL Male groups when compared with CP Male. CLP and CP groups present a pattern of occurrence of the type of cleft in the family.

Maternal periconceptional folic acid supplementation reduced risks of non-syndromic oral clefts in offspring

Maternal periconceptional folic acid supplementation (FAS) has been documented to be associated with decreased risk of nonsyndromic oral clefts (NsOC). However, the results remain inconclusive. In this population-based case–control study of 807 singletons affected by NsOC and 8070 healthy neonates who were born between October 2010 and September 2015 in Chengdu, China, we examined the association of maternal FAS with the risk of nonsyndromic cleft lip with or without cleft palate (NsCL/P), and cleft palate (NsCP). Unconditional logistic regression analysis was used to estimate the crude and adjusted odds ratios (ORs) and 95% confidential intervals (CI). Significant associations were found between maternal periconceptional FAS and decreased risk of NsCL/P (aOR = 0.41, 95% CI 0.33–0.51). This protective effect was also detected for NsCL (aOR = 0.42, 95% CI 0.30–0.58) and NsCLP (aOR = 0.41, 95% CI 0.31–0.54). Both maternal FAS started before and after the last menstrual period (LMP) were inversely associated with NsCL/P (before LMP, aOR = 0.43, 95% CI 0.33–0.56; after LMP, aOR = 0.41, 95% CI 0.33–0.51). The association between NsCP and maternal FAS initiating before LMP was also found (aOR = 0.52, 95% CI 0.30–0.90). The findings suggest that maternal periconceptional FAS can reduce the risk of each subtype of NsCL/P in offspring, while the potential effect on NsCP needs further investigations.

Cleft Lip and/or Palate and Associated Risks in Lower-Middle-Income Countries: A Systematic Review

OBJECTIVE

To identify and review published data on the risks associated with cleft lip and/or palate (CL/P) in lower-middle-income countries (LMICs).

DESIGN

A systematic review of literature was performed on electronic databases using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols. Literature on risks associated with CL/P in LMICs, from 2010 to 2020, were included.

RESULTS

Seventeen studies met the inclusion criteria. All studies adopted an observational study design. Biological and environmental risks were identified. Maternal and paternal age (n = 7) and low socioeconomic status (n = 5) were the most prominently associated environmental risk factors. A strong association was identified between family history of cleft (n = 7) and CL/P occurrence.

CONCLUSION

Environmental risk factors are now being investigated more than biological risk factors in LMICs, aiding health care workers in the early identification of possible cumulative effects of risks in CL/P. Contextually relevant tools are recommended to promote early identification of at-risk infants.

Orofacial clefts embryology, classification, epidemiology, and genetics

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

Seasonal Influence on the Numbers of Gender-Related Orofacial Cleft Conceptions in the Netherlands

BACKGROUND

In the multifactorial etiology of orofacial clefts (OFCs), environmental factors play an important role. To trace the influence of these factors, the timing of the cell biological mechanisms that occur during embryological development of the primary and secondary palates must be taken into account. That is, the fusion process of the facial and palatal processes, respectively, followed by their differentiation into bone and musculature, which take place during the first trimester of pregnancy. During this period, harmful seasonal influences such as viral infections and vitamin deficiencies could induce OFC in the embryo.

AIMS

The aim of this study is to find out whether a seasonal conception period with an increased risk of OFC development exists, particularly gender related.

METHODS

This was a retrospective cross-sectional study on children with OFC born in the Netherlands from 2006 to 2016. Total conception rates of live births in the Netherlands were used as a control group. χ² tests were performed to analyze monthly and seasonal differences. Males and females, positive and negative family history and subphenotype groups based on fusion and/or differentiation (F- and/or D-) defects, and their timing in embryogenesis were analyzed separately.

RESULTS

In total, 1653 children with OFC, 1041 males and 612 females, were analyzed. Only males with FD-defects showed a significant seasonal variation with an increase in conceptions during spring, most often in May.

CONCLUSIONS

Males with FD-defects showed a significant seasonal variation with an increase in conceptions during spring. No other seasonal trends could be demonstrated.

Gene-Environment Interplay and MicroRNAs in Cleft Lip and Cleft Palate

Cleft lip (CL) with/without cleft palate (CP) (hereafter CL/P) is the second most common congenital birth defect, affecting 7.94 to 9.92 children per 10,000 live births worldwide, followed by Down syndrome. An increasing number of genes have been identified as affecting susceptibility and/or as causative genes for CL/P in mouse genetic and chemically-induced CL and CP studies, as well as in human genome-wide association studies and linkage analysis. While marked progress has been made in the identification of genetic and environmental risk factors for CL/P, the interplays between these factors are not yet fully understood. This review aims to summarize our current knowledge of CL and CP from genetically engineered mouse models and environmental factors that have been studied in mice. Understanding the regulatory mechanism(s) of craniofacial development may not only advance our understanding of craniofacial developmental biology, but could also provide approaches for the prevention of birth defects and for tissue engineering in craniofacial tissue regeneration.

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.

Folate intake, markers of folate status and oral clefts: An updated set of systematic reviews and meta-analyses

BACKGROUND

There has been a longstanding debate about the role of folate in the etiology of orofacial clefts (OFCs). Studies of different measures of nutritional intake or folate status have been done to investigate the possible role of folate in the prevention of OFC. Only one knowledge synthesis has attempted to bring together different types of evidence. The aim of the present work was to update it.

METHODS

Evidence for associations between OFC and dietary folate, supplement use, folic acid fortification, biomarkers of folate status, and variants of MTHFR (C677T and A1298C) were included. Potentially eligible articles were systematically identified from PubMed, Medline, Embase, and Web of Science (2007-2020) and combined using random-effects meta-analysis when appropriate. Quality assessments were conducted using the Newcastle-Ottawa scale and Cochrane's risk of bias tool.

RESULTS

Sixty-four studies published since the previous knowledge synthesis were identified, with eight of these identified through a supplementary search from October, 2018 to August, 2020. There was an inverse association between folic acid-containing supplement use before or during pregnancy and cleft lip with or without cleft palate (CL/P) (OR 0.60, 95% CI 0.51-0.69), with considerable between-study heterogeneity. The prevalence of CL/P showed a small decline post-folic acid fortification in seven studies (OR 0.94, 95% CI 0.86-1.02). No association was found between OFC and genetic markers of folate status. The coronavirus-19 pandemic has threatened food availability globally and therefore there is a need to maintain and even enhance surveillance concerning maternal intake of folate and related vitamins.

CONCLUSIONS

The risk of non-syndromic OFC was reduced among pregnant women with folic acid-containing supplements during the etiologically relevant period. However, high heterogeneity between included studies, incomplete reporting of population characteristics and variation in timing of exposure and supplement types mean that conclusions should be drawn with caution.

Association of Genetic Polymorphisms of GREM1 Gene with Susceptibility to Non-Syndromic Cleft Lip with or without Cleft Palate in an Iranian Population

Background: Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is common congenital birth anomaly with multifactorial etiology. The GREM1 gene has been proposed to play a role in oral clefts development.Objective: The aim of the present study was to evaluate the correlation between GREM1 polymorphisms and the risk of NSCL/P in an Iranian population.Methods: Genotyping of rs7162202, rs12915554, rs3743105, rs1129456, and rs10318 polymorphisms of GREM1 gene in 150 NSCL/P and 152 healthy subjects was determined by the PCR-RFLP or T-ARMS-PCR.Results: The findings showed that the rs12915554 variant significantly increased the risk of NSCL/P in heterozygous (OR = 4.20, 95%CI = 2.46-7.11, p < 0.0001, AC vs AA), and allele (OR = 3.17, 95%CI = 2.00-5.08, p < 0.0001, C vs A) genetic models. The rs3743105 polymorphism was correlated with reduced risk of NSCL/P in heterozygous (OR = 0.49, 95%CI = 0.29-0.83, p = 0.008, AG vs GG) and dominant (OR = 0.54, 95%CI = 0.33-0.89, p = 0.018, GA + AA vs GG) genetic models. The rs1129456 variant was positively associated with the risk of NSCL/P in heterozygous (OR = 2.91, 95%CI = 1.12-7.38, p = 0.028, AT vs AA) and allele (OR = 2.80, 95%CI = 2.80-6.95, p = 0.031, T vs C). The rs10318 polymorphism significantly reduced NSCL/P risk in homozygous (OR = 0.20, 95%CI = 0.06-0.67, p = 0.013, TT vs CC), dominant (OR = 0.57, 95%CI = 0.36-0.91, p = 0.019, CT + CC vs CC), recessive (OR = 0.24, 95%CI = 0.07-0.76, p = 0.031, TT vs CT + CC), and allele (OR = 0.57, 95%CI = 0.38-0.84, p = 0.005, T vs C). No correlation was observed between rs7162202 polymorphism and NSCL/P.Conclusion: The findings support that GREM1 polymorphisms are involved in NSCL/P susceptibility in an Iranian population.

Assessment of the correlation between various risk factors and orofacial cleft disorder spectrum: a retrospective case-control study

Background

Orofacial clefts (OFCs) comprise a wide range of malformations, including cleft lip, cleft palate, and cleft lip with cleft palate, which can vary in terms of etiology, severity, and disease burden.

Objective(s)

This study aimed to evaluate the correlation between various risk factors and orofacial cleft disorder spectrum in newborns.

Study design

A total of 323 cases and 400 controls were enrolled in this study and evaluated in terms of the maternal history of abortion or miscarriage, child’s sex, maternal and paternal age, maternal history of systemic disease, history of medication therapy during pregnancy, birth order, consanguineous marriage, and complications during pregnancy.

Results

Analysis of the results suggested that consanguineous marriage, a maternal history of abortion/miscarriage, and complications during pregnancy could potentially increase the risk of OFCs in children (P < 0.05). However, the analyses revealed that the other variables could not potentially increase the risk of OFCs (P > 0.05).

Conclusion(s)

Multiple cofactors may simultaneously contribute to the formation of such abnormalities; therefore, a comprehensive, multidisciplinary care program is necessary to ensure a successful pregnancy period and the birth of a healthy newborn.

Levels of uranium and thorium in maternal scalp hair and risk of orofacial clefts in offspring

Uranium and thorium are common radioactive elements that exist in the environment. However, few environmental epidemiological studies have focused on their possible effects on congenital malformations. Here, we explored the association between uranium and thorium concentrations in maternal scalp hair grown from 3 months before to 3 months after conception, namely during the periconceptional period and the risk of orofacial clefts (OFCs) in offspring. Our study included 153 women whose pregnancies were affected by OFCs (cases) and 601 women who delivered infants without birth defects (controls) from four provinces in China. Face-to-face interviews were used to collect sociodemographic characteristics with a structured questionnaire. Concentrations of uranium and thorium in maternal scalp hair grown during the periconceptional period were detected using inductively coupled plasma-mass spectrometry. The risk of OFCs in association with higher concentrations of the two radioactive elements was estimated using odds ratios (ORs) and 95% confidence intervals (CIs) while adjusting for potential confounding factors. The levels of uranium and thorium in maternal hair were in agreement with the published literature. After adjusting for several confounders, the ORs of thorium in the highest, upper, and lower quartile versus the lowest quartile were 2.63 (95% CI, 1.41-4.92), 1.98 (95% CI, 1.03-3.79), and 2.73 (95% CI, 1.46-5.12), respectively. No association was found between levels of uranium and the risk of OFCs. Maternal periconceptional exposure to thorium may be a risk factor for OFCs in offspring.

Association of single nucleotide polymorphisms in TPM1 rs11071720, rs3803499, rs12148828, and rs1972041 with the risk of nonsyndromic cleft lip with or without cleft palate in a sample of the Iranian population, a preliminary report

Several lines of evidence support an association between tropomyosin 1 (TPM1) and the risk of nonsyndromic cleft lip with or without cleft palate (NSCL/P). The present study aimed to investigate the association between TPM1 polymorphisms and the risk of NSCL/P in an Iranian population. This case-control was done on 105 NSCL/P patients and 110 unrelated healthy controls. TPM1 rs11071720, rs3803499, rs12148828, and rs1972041 polymorphisms were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. The finding showed that rs11071720 polymorphism significantly increased the risk of NSCL/P in homozygous codominant (odds ratio [OR] = 2.54, 95% confidence interval [CI] = 1.14-5.69, p = 0.023, TT vs. CC), recessive (OR = 2.33, 95% CI = 1.06-5.18, p = 0.021, TT vs. CT + CC), and allele (OR = 1.53, 95% CI = 1.02-2.30, p = 0.030, T vs. C). The rs12148828 polymorphism was associated with protection against NSCL/P in codominant (OR = 0.27, 95% CI = 0.15-0.48, p < 0.001, TC vs. TT) and allele (OR = 0.38, 95% CI = 0.22-0.64, p < 0.001, C vs. T). Regarding rs3803499, the findings proposed that this polymorphism significantly increased the risk of NSCL/P in codominant (OR = 3.86, 95% CI = 1.19-12.56, p = 0.025, CC vs. TT) and recessive (OR = 3.74, 95% CI = 1.09-14.15, p = 0.018, CC vs. CT + TT). No significant association was practical between rs1972041 polymorphism and NSCL/P. In conclusion, the findings proposed that TPM1 polymorphisms may contribute to the etiology of NSCL/P in a sample of the Iranian population.