Genetic Factors and Orofacial Clefting

Prenatal diagnosis of cleft lip and/or palate: What do we tell prospective parents?

Cleft lip and/or palate (CL/CP) is the most common congenital craniofacial anomaly and parents often ask, "how did this happen?" Patients and families may benefit from access to a multidisciplinary team (MDT) from prenatal diagnosis into early adulthood. Multiple factors can contribute to the development of a cleft. We discuss the epidemiology and risk factors that increase the likelihood of having a newborn with a cleft. The purpose of this article is to review the prenatal investigations involved in the diagnosis and workup of these patients in addition to postpartum treatment, prognostic factors, and counseling families regarding future recurrence risk.

Outcomes of permanent canines on the cleft side after secondary alveolar grafting using different materials in complete unilateral cleft lip and palate

The prevalence of impaction of the permanent canine on the cleft side (PCCS) ranges from 12-35% after alveolar bone grafting (ABG). PCCSs usually develop above other permanent teeth in the alveolar process, gradually becoming vertical until they reach the occlusal plane. The type of cleft, hypodontia of lateral incisor on the cleft side, slower PCCS root development, and genetic factors are predictors of impaction and/or its ectopic eruption. To compare the behavior of PCCS in individuals with complete unilateral cleft lip and palate (UCLP) subjected to secondary alveolar grafting (SAG) with different materials. This retrospective longitudinal study analyzed 120 individuals undergoing SAG with iliac crest bone, rhBMP-2, and mandibular symphysis. The individuals were selected at a single center and equally divided into three groups. Panoramic radiographs were analyzed by the Dolphin Imaging 11.95 software to measure PCCS angulation and PCCS height from the occlusal plane at two different timepoints. No statistical significance was found between grafting materials (P=0.416). At T1, the PCCS height from the occlusal plane was greater for rhBMP-2 and mandibular symphysis compared to iliac crest bone. The lateral incisor on the cleft side was not related to success or lack of eruption of PCCS (P=0.870). Impaction rates of PCCS were similar for the materials studied. Absence of the lateral incisor on the cleft side did not prevent spontaneous eruption of PCCSs.

Surgical rehabilitation of cleft lip and/or palate: evaluation of the Brazilian public health system

OBJECTIVE

To evaluate the surgical rehabilitation of cleft lip and/or palate by the Brazilian public health system.

METHODS

Retrospective, analytical and comparative ecological study, with information on hospital procedures performed on individuals with cleft lip and/or palate in Centers authorized by the Brazilian public health system, between the years 2008 and 2020. The information was collected in databases Ministry of Health data.

RESULTS

Between 2008 and 2020, there was an increase of 8 (36.4%) qualified Centers in Brazil, currently having 30 Centers in 100% of the geographic regions. The surgical procedures performed totaled 68,716; with multiple surgeries being the most frequent. Complete cleft lip and palate was the most frequent type in hospital admissions. The public financial resources invested in the surgical rehabilitation of cleft lip and palate in the qualified Lip and Palate Malformation Treatment Centers were US$ 39,693 million, making an average value per procedure of US$ 577.64.

CONCLUSIONS

In Brazil, public health system performed and financed, over the years 2008 and 2020, an important volume of surgical procedures for cleft lip and/or palate, which presented a polarization in the Southeast region but with a slight tendency expansion to other regions of the country. The most performed surgical procedures were multiple surgeries and mostly for individuals with cleft lip and palate. The amounts paid showed a heretogeneous distribution in the national territory.

LEVEL OF EVIDENCE

Level 5: Report containing program evaluation data.

Environmental Factors at the Periconceptional Period and the Occurrence of Cleft Lip and Palate in a Midwest Brazil Population: A Case-Control Study

OBJECTIVE

To investigate the association between periconceptional environmental exposures and the occurrence of cleft lips and palates.

METHODS

This case-control study analyzed 150 mothers of children with cleft lips and palates living in the same city as 250 mothers whose children did not present with this malformation (controls). Environmental exposure data were gathered through a questionnaire (Latin American Collaborative Study of Congenital Malformations methodology).

RESULTS

Multivariate analysis revealed that monthly income below minimum wage, having another malformed child, other diseases in the first gestational trimester (urinary infection), use of pesticides in home gardens, and pesticide use in farms close to the home were risk factors associated with the malformation, whereas taking vitamins was a protective factor.

CONCLUSION

Maternal and paternal exposure to pesticides is associated with cleft lip and palate in Mato Grosso State, Brazil.

Dental anomalies in non-syndromic orofacial clefts: a clinical approach

Orofacial clefts (OC) represent some of the most common congenital malformations and affect multiple structures in the craniofacial region. There are a wide range of morphological OC types within the spectrum of both non-syndromic OC (NSOC) and syndromic OC, including cleft lip (CL); cleft lip and palate (CLP) and cleft palate (CP). Here, we describe the most frequent dental anomalies seen in the permanent dentition of individuals with NSOC, comparing them between the three main cleft types (CL, CLP, CP). We present these findings from the perspective of prevalence relating to each anomaly, as well as the clinical characteristics and potential impact in the rehabilitation process. The investigation of dental anomalies associated with NSOC is important, helping to expand the phenotypic characterization of NSOC, improve initial diagnostics and establish appropriate rehabilitation and counseling.

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.

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.

A Microphysiological Approach to Evaluate Effectors of Intercellular Hedgehog Signaling in Development

Paracrine signaling in the tissue microenvironment is a central mediator of morphogenesis, and modeling this dynamic intercellular activity in vitro is critical to understanding normal and abnormal development. For example, Sonic Hedgehog (Shh) signaling is a conserved mechanism involved in multiple developmental processes and strongly linked to human birth defects including orofacial clefts of the lip and palate. SHH ligand produced, processed, and secreted from the epithelial ectoderm is shuttled through the extracellular matrix where it binds mesenchymal receptors, establishing a gradient of transcriptional response that drives orofacial morphogenesis. In humans, complex interactions of genetic predispositions and environmental insults acting on diverse molecular targets are thought to underlie orofacial cleft etiology. Consequently, there is a need for tractable in vitro approaches that model this complex cellular and environmental interplay and are sensitive to disruption across the multistep signaling cascade. We developed a microplate-based device that supports an epithelium directly overlaid onto an extracellular matrix-embedded mesenchyme, mimicking the basic tissue architecture of developing orofacial tissues. SHH ligand produced from the epithelium generated a gradient of SHH-driven transcription in the adjacent mesenchyme, recapitulating the gradient of pathway activity observed in vivo. Shh pathway activation was antagonized by small molecule inhibitors of epithelial secretory, extracellular matrix transport, and mesenchymal sensing targets, supporting the use of this approach in high-content chemical screening of the complete Shh pathway. Together, these findings demonstrate a novel and practical microphysiological model with broad utility for investigating epithelial-mesenchymal interactions and environmental signaling disruptions in development.

Multifactorial Genetic and Environmental Hedgehog Pathway Disruption Sensitizes Embryos to Alcohol-Induced Craniofacial Defects

BACKGROUND

Prenatal alcohol exposure (PAE) is perhaps the most common environmental cause of human birth defects. These exposures cause a range of structural and neurological defects, including facial dysmorphologies, collectively known as fetal alcohol spectrum disorders (FASD). While PAE causes FASD, phenotypic outcomes vary widely. It is thought that multifactorial genetic and environmental interactions modify the effects of PAE. However, little is known of the nature of these modifiers. Disruption of the Hedgehog (Hh) signaling pathway has been suggested as a modifier of ethanol teratogenicity. In addition to regulating the morphogenesis of craniofacial tissues commonly disrupted in FASD, a core member of the Hh pathway, Smoothened, is susceptible to modulation by structurally diverse chemicals. These include environmentally prevalent teratogens like piperonyl butoxide (PBO), a synergist found in thousands of pesticide formulations.

METHODS

Here, we characterize multifactorial genetic and environmental interactions using a zebrafish model of craniofacial development.

RESULTS

We show that loss of a single allele of shha sensitized embryos to both alcohol- and PBO-induced facial defects. Co-exposure of PBO and alcohol synergized to cause more frequent and severe defects. The effects of this co-exposure were even more profound in the genetically susceptible shha heterozygotes.

CONCLUSIONS

Together, these findings shed light on the multifactorial basis of alcohol-induced craniofacial defects. In addition to further implicating genetic disruption of the Hh pathway in alcohol teratogenicity, our findings suggest that co-exposure to environmental chemicals that perturb Hh signaling may be important variables in FASD and related craniofacial disorders.

Innovative Molecular and Cellular Therapeutics in Cleft Palate Tissue Engineering

Clefts of the lip and/or palate are the most prevalent orofacial birth defects occurring in about 1:700 live human births worldwide. Early postnatal surgical interventions are extensive and staged to bring about optimal growth and fusion of palatal shelves. Severe cleft defects pose a challenge to correct with surgery alone, resulting in complications and sequelae requiring life-long, multidisciplinary care. Advances made in materials science innovation, including scaffold-based delivery systems for precision tissue engineering, now offer new avenues for stimulating bone formation at the site of surgical correction for palatal clefts. In this study, we review the present scientific literature on key developmental events that can go awry in palate development and the common surgical practices and challenges faced in correcting cleft defects. How key osteoinductive pathways implicated in palatogenesis inform the design and optimization of constructs for cleft palate correction is discussed within the context of translation to humans. Finally, we highlight new osteogenic agents and innovative delivery systems with the potential to be adopted in engineering-based therapeutic approaches for the correction of palatal defects. Impact statement Tissue-engineered scaffolds supplemented with osteogenic growth factors have attractive, largely unexplored possibilities to modulate molecular signaling networks relevant to driving palatogenesis in the context of congenital anomalies (e.g., cleft palate). Constructs that address this need may obviate current use of autologous bone grafts, thereby avoiding donor-site morbidity and other regenerative challenges in patients afflicted with palatal clefts. Combinations of biomaterials and drug delivery of diverse regenerative cues and biologics are currently transforming strategies exploited by engineers, scientists, and clinicians for palatal cleft repair.

Genetic variants of microRNA processing genes and risk of non-syndromic orofacial clefts

OBJECTIVE

MicroRNA (miRNA) processing genes play important roles in the craniofacial development. The aim of this study was to explore the associations between single nucleotide polymorphisms (SNPs) of miRNA processing genes with the risk of non-syndromic orofacial clefts (NSOC).

METHODS

We genotyped 12 potentially functional SNPs from seven miRNA processing genes (GEMIN3, DROSHA, DGCR8, GEMIN4, PIWIL1, XPO5, and DICER) in a case-control study of 602 NSOC cases and 605 controls.

RESULTS

Two SNPs were associated with the susceptibility of CL/P: rs10719 in DROSHA led to an increased risk of cleft lip with or without palate (CL/P) (GA/AA: p = .024, OR = 1.33, 95% CI = [1.04, 1.70]; GG + GA/AA: p = .037, OR = 1.29, 95% CI = [1.02, 1.63]), while rs493760 in DROSHA (CC/TT: p = .049, OR = 0.58, 95% CI = [0.34, 0.99]) could reduce the risk of CL/P. In addition, rs10719 (A)-rs493760 (C) haplotype contributed to a decreased risk of CL/P (OR = 0.77, 95% CI = [0.63, 0.94]), whereas the rs10719 (G)-rs493760 (C) haplotype contributed to the increased risk of cleft palate only (CPO) (OR = 2.70, 95% CI = [1.15, 6.35]). However, there was no difference observed in these SNPs after the Bonferroni correction.

CONCLUSION

Taken together, our results provided the potential evidence that rs10719 and rs493760 might contribute to the risk of CL/P and suggested potential genetic basis and mechanisms of CL/P. The lack of association between these SNPs and CPO might be due to the limited sample size of CPO subgroup.

A cross-sectional analysis of the prevalence of tooth agenesis and structural dental anomalies in association with cleft type in non-syndromic oral cleft patients

Background

The aim of this study was to investigate the prevalence of tooth agenesis, microdontia, and tooth malformation among non-syndromic oral cleft patients and their potential association with cleft type and gender.

Methods

Intraoral records and radiographs of 154 patients (97 males and 57 females) were examined. The variables assessed were tooth agenesis, microdontia, dental malformations, and cleft types. The statistics included chi-square and Fisher’s exact tests as well as logistic regression to assess any mutual effects of gender and cleft type on the dental variables.

Results

Tooth agenesis occurred in 50% of the sample and microdontia in 18%. Non-statistically significant odds ratios for the association of gender and cleft type with tooth agenesis were obtained. Tooth agenesis was substantially higher at the unilateral right CL + P and the bilateral CL + P in quadrant 1 and at the unilateral left CL + P and bilateral CL + P in quadrant 2. It was also higher, at the isolated cleft palate (CP) in quadrants 3 and 4. These results were attributed to teeth 22 (31.8%) and 12 (21.6%) in the maxilla and to teeth 35 (6.1%) and 45 (5.4%) in the mandible. In unilateral CL + P patients, the cleft quadrant that presented tooth agenesis was associated with the side of the cleft.

Conclusions

Interdisciplinary treatment of the oral cleft patients should take into consideration the high prevalence of tooth agenesis and their association with the different cleft types. The most frequently affected teeth by cleft are by far the upper lateral incisors. Results indicate that tooth agenesis appears to be a genetically controlled anomaly related to the orofacial cleft development through various genetic links and not caused by the cleft disruptive process.

Sonic hedgehog regulation of Foxf2 promotes cranial neural crest mesenchyme proliferation and is disrupted in cleft lip morphogenesis

Cleft lip is one of the most common human birth defects, yet our understanding of the mechanisms that regulate lip morphogenesis is limited. Here, we show in mice that sonic hedgehog (Shh)-induced proliferation of cranial neural crest cell (cNCC) mesenchyme is required for upper lip closure. Gene expression profiling revealed a subset of Forkhead box (Fox) genes that are regulated by Shh signaling during lip morphogenesis. During cleft pathogenesis, reduced proliferation in the medial nasal process mesenchyme paralleled the domain of reduced Foxf2 and Gli1 expression. SHH ligand induction of Foxf2 expression was dependent upon Shh pathway effectors in cNCCs, while a functional GLI-binding site was identified downstream of Foxf2 Consistent with the cellular mechanism demonstrated for cleft lip pathogenesis, we found that either SHH ligand addition or FOXF2 overexpression is sufficient to induce cNCC proliferation. Finally, analysis of a large multi-ethnic human population with cleft lip identified clusters of single-nucleotide polymorphisms in FOXF2 These data suggest that direct targeting of Foxf2 by Shh signaling drives cNCC mesenchyme proliferation during upper lip morphogenesis, and that disruption of this sequence results in cleft lip.

Bone morphogenetic protein type I receptor inhibition induces cleft palate associated with micrognathia and cleft lower lip in mice

BACKGROUND

Gain-of- and loss-of-function studies have demonstrated that changes in bone morphogenetic protein (BMP) signaling during embryo development cause craniofacial malformations, including cleft palate. It remains uncertain whether BMP signaling could be targeted pharmacologically to affect craniofacial morphogenesis.

METHODS

Pregnant C57Bl/6J mice were treated with the BMP type I receptor inhibitor LDN-193189 at the dose of 3, 6, or 9 mg/kg twice a day by intraperitoneal injection from embryonic day 10.5 (E10.5) to E15.5. At E16.5, embryos were investigated by facial measurement analysis and histology to determine the optimal concentration for malformation. Subsequent embryonic phenotypes were analyzed in detail by histology, whole-mount skeletal staining, micro-computed tomography, and palatal organic culture. We further used immunohistochemistry to analyze protein expression of the BMP-mediated canonical and noncanonical signaling components.

RESULTS

The optimal concentration of LDN-193189 was determined to be 6 mg/kg. In utero, LDN-193189 exposures induced partial clefting of the anterior palate or complete cleft palate, which was attributed to a reduced cell proliferation rate in the secondary palate, and delayed palatal elevation caused by micrognathia. Analysis of signal transduction in palatal shelves at E12.5 and E13.5 identified a significant reduction of BMP/Smad signaling (p-Smad1/5/8) and unchanged BMP noncanonical signaling (p-p38, p-Erk1/2) after treatment with LDN-193189.

CONCLUSION

The results of this study indicate that LDN-193189 can be used to manipulate BMP signaling by selectively targeting the BMP/Smad signaling pathway to affect palatal morphogenesis and produce phenotypes mimicking those caused by genetic mutations. This work established a novel mouse model for teratogen-induced cleft palate. Birth Defects Research (Part A) 106:612-623, 2016. © 2016 Wiley Periodicals, Inc.

Epidemiology, Etiology, and Treatment of Isolated Cleft Palate

Isolated cleft palate (CPO) is the rarest form of oral clefting. The incidence of CPO varies substantially by geography from 1.3 to 25.3 per 10,000 live births, with the highest rates in British Columbia, Canada and the lowest rates in Nigeria, Africa. Stratified by ethnicity/race, the highest rates of CPO are observed in non-Hispanic Whites and the lowest in Africans; nevertheless, rates of CPO are consistently higher in females compared to males. Approximately fifty percent of cases born with cleft palate occur as part of a known genetic syndrome or with another malformation (e.g., congenital heart defects) and the other half occur as solitary defects, referred to often as non-syndromic clefts. The etiology of CPO is multifactorial involving genetic and environmental risk factors. Several animal models have yielded insight into the molecular pathways responsible for proper closure of the palate, including the BMP, TGF-β, and SHH signaling pathways. In terms of environmental exposures, only maternal tobacco smoke has been found to be strongly associated with CPO. Some studies have suggested that maternal glucocorticoid exposure may also be important. Clearly, there is a need for larger epidemiologic studies to further investigate both genetic and environmental risk factors and gene-environment interactions. In terms of treatment, there is a need for long-term comprehensive care including surgical, dental and speech pathology. Overall, five main themes emerge as critical in advancing research: (1) monitoring of the occurrence of CPO (capacity building); (2) detailed phenotyping of the severity (biology); (3) understanding of the genetic and environmental risk factors (primary prevention); (4) access to early detection and multidisciplinary treatment (clinical services); and (5) understanding predictors of recurrence and possible interventions among families with a child with CPO (secondary prevention).

Long-term effects of oral clefts on health care utilization: a sibling comparison

Oral clefts are among the most common birth defects affecting thousands of newborns each year, but little is known about their potential long-term consequences. In this paper, we explore the impact of oral clefts on health care utilization over most of the lifespan. To account for time-invariant unobservable parental characteristics, we compare affected individuals with their own unaffected siblings. The analysis is based on unique data comprising the entire cohort of individuals born with oral clefts in Denmark tracked until adulthood in administrative register data. We find that children with oral clefts use more health services than their unaffected siblings. Additional results show that the effects are driven primarily by congenital malformation-related hospitalizations and intake of anti-infectives. Although the absolute differences in most health care utilization diminish over time, affected individuals have slightly higher utilization of some health care services in adulthood (particularly for diseases of the nervous and respiratory system). These results have important implications for affected individuals, their families, and their health professionals.

Analysis of potential oral cleft risk factors in the Kosovo population

The aim of this study was to analyze the association of potential risk factors such as positive family cleft history, smoking, use of drugs during pregnancy, and parental age with oral clefts in offspring within the Kosovo population. We conducted a population-based case-control study of live births in Kosovo from 1996 to 2005. Using a logistic regression model, 244 oral cleft cases were compared with 488 controls. We have excluded all syndromic clefts. Heredity increases the risk of clefts in newborns [odds ratio (OR) = 8.25, 95% confidence interval (CI) 3.12-23.52]. Clefts were also associated with smoking (OR = 1.87, 95% CI 0.75-4.08), use of drugs during pregnancy (OR = 2.25, 95% CI 0.82-5.12), increasing maternal age (OR = 1.83, 95% CI 1.42-2.49), and increasing paternal age (OR = 1.3, 95% CI 1.2- 1.4). We found heredity to be the most important factor for cleft occurrence in Kosovar newborns. Another significant potential risk factor for occurrence of clefts is the parental age. We found the use of drugs and smoking during pregnancy to be less significant.

Genomic expression in non syndromic cleft lip and palate patients: A review

Cleft lip and palate are common congenital anomalies with significant medical, psychological, social, and economic ramifications, affecting one in seven hundred live births. Genetic causes of non syndromic cleft lip and/or palate (NSCLP) include chromosomal rearrangements, genetic susceptibility to teratogenic exposures, and complex genetic contributions of multiple genes. Development of the orofacial clefts in an individual will depend on the interaction of several moderately effecting genes with environmental factors. Several candidate genes have been genotyped in different population types, using case parent trio or case control design; also genes have been sequenced and SNPs have been reported. Quantitative and molecular analysis have shown linkage and association studies to be more relevant. Recent literature search shows genome wide association studies using microarray. The aim of this paper was to review the approaches to identify genes associated with NSCLP and to analyze their differential expressions. Although no major gene has been confirmed, a lot of research is ongoing to provide an understanding of the pathophysiology of the orofacial clefts.

Definition of critical periods for Hedgehog pathway antagonist-induced holoprosencephaly, cleft lip, and cleft palate

The Hedgehog (Hh) signaling pathway mediates multiple spatiotemporally-specific aspects of brain and face development. Genetic and chemical disruptions of the pathway are known to result in an array of structural malformations, including holoprosencephaly (HPE), clefts of the lip with or without cleft palate (CL/P), and clefts of the secondary palate only (CPO). Here, we examined patterns of dysmorphology caused by acute, stage-specific Hh signaling inhibition. Timed-pregnant wildtype C57BL/6J mice were administered a single dose of the potent pathway antagonist vismodegib at discrete time points between gestational day (GD) 7.0 and 10.0, an interval approximately corresponding to the 15^th to 24^th days of human gestation. The resultant pattern of facial and brain dysmorphology was dependent upon stage of exposure. Insult between GD7.0 and GD8.25 resulted in HPE, with peak incidence following exposure at GD7.5. Unilateral clefts of the lip extending into the primary palate were also observed, with peak incidence following exposure at GD8.875. Insult between GD9.0 and GD10.0 resulted in CPO and forelimb abnormalities. We have previously demonstrated that Hh antagonist-induced cleft lip results from deficiency of the medial nasal process and show here that CPO is associated with reduced growth of the maxillary-derived palatal shelves. By defining the critical periods for the induction of HPE, CL/P, and CPO with fine temporal resolution, these results provide a mechanism by which Hh pathway disruption can result in “non-syndromic” orofacial clefting, or HPE with or without co-occurring clefts. This study also establishes a novel and tractable mouse model of human craniofacial malformations using a single dose of a commercially available and pathway-specific drug.

Association between Maternal MTHFR Polymorphisms and Nonsyndromic Cleft Lip with or without Cleft Palate in Offspring, A Meta-Analysis Based on 15 Case-Control Studies

Background

The methylenetetrahydrofolate reductase (MTHFR) is thought to be involved in the development of nonsyndromic cleft lip with or without cleft palate (NSCL/P). However, conflicting results have been obtained when evaluating the association between maternal MTHFR C677T and A1298C polymorphisms and the risk of NSCL/P. In light of this gap, a meta-analysis of all eligible case-control studies was conducted in the present study.

Materials and Methods

A total of 15 case-control studies were ultimately identified after a comprehensive literature search and Hardy-Weinberg equilibrium (HWE) examination. Cochrane’s Q test and index of heterogeneity (I²) indicated no obvious heterogeneity among studies.

Results

Fixed or random-effects models were used to calculate the pooled odds ratios (ORs). The results showed that the TT genotype in mothers increased the likelihood of having NSCL/P offspring 1.25 times (95% CI: 1.047-1.494) more than the CC homozygotes. Meanwhile, maternal TT genotype increased the risk of producing NSCL/P offspring in recessive model (OR=1.325, 95% CI: 1.124-1.562). However, the CT heterozygote and the CT+TT dominant models had no association with NSCL/P offspring compared with the CC wild-type homozygote model. Subgroup analyses based on ethnicity indicated that maternal TT genotype increased the likelihood of having NSCL/P offspring in Whites (OR=1.308, 95% CI: 1.059-1.617) and Asians (OR=1.726, 95% CI: 1.090-2.733) in recessive model. Also, subgroup analyses based on source of control showed that mothers with the 677TT genotype had a significantly increased susceptibility of having NSCL/P children in hospital based population (HB) when compared with CC homozygotes (OR=1.248, 95% CI: 1.024-1.520) and un- der the recessive model (OR=1.324, 95% CI: 1.104-1.588). Furthermore, maternal A1298C polymorphism had no significant association with producing NSCL/P offspring (dominant model OR=0.952, 95% CI: 0.816-1.111, recessive model OR=0.766, 95% CI: 0.567-1.036).

Conclusion

MTHFR C677T polymorphism is associated with the risk of generating NSCL/P offspring, and being a 677TT homozygote is a risk factor. MTHFR A1298C polymorphism was not associated with generating NSCL/P offspring. However, further work should be performed to confirm these findings.

The prevalence of specific dental anomalies in a group of Saudi cleft lip and palate patients

Objective

The aims of this study were to investigate the prevalence and distribution of dental anomalies in a group of Saudi subjects with cleft lip and palate (CLP), to examine potential sex-based associations of these anomalies, and to compare dental anomalies in Saudi subjects with CLP with published data from other population groups.

Design

This retrospective study involved the examination of pre-treatment records obtained from three CLP centers in Riyadh, Saudi Arabia, in February and March 2010. The pre-treatment records of 184 subjects with cleft lip and palate were identified and included in this study. Pre-treatment maxillary occlusal radiographs of the cleft region, panoramic radiographs, and orthodontic study models of subjects with CLP were analyzed for dental anomalies.

Results

Orthopantomographs and occlusal radiographs may not be reliable for the accurate evaluation of root malformation anomalies. A total of 265 dental anomalies were observed in the 184 study subjects. Hypodontia was observed most commonly (66.8%), followed by microdontia (45.6%), intra-oral ectopic eruption (12.5%), supernumerary teeth (12.5%), intra-nasal ectopic eruption (3.2), and macrodontia (3.2%). No gender difference in the prevalence of these anomalies was observed.

Conclusions

Dental anomalies were common in Saudi subjects with CLP type. This will complicate the health care required for the CL/P subjects. This study was conducted to epidemiologically explore the prevalence of dental anomalies among Saudi Arabian subjects with CLP.

Identification of a novel heterozygous truncation mutation in exon 1 of ARHGAP29 in an Indian subject with nonsyndromic cleft lip with cleft palate

Objective:

Mutations in exon 1 of ARHGAP29, a RhoA specific GTPase have been identified in North American and Filipino subjects with nonsyndromic cleft palate and cleft lip with or without cleft palate. Since the genetic status of ARHGAP29 in Indian subjects with nonsyndromic oral clefts is not known, we designed the present study to investigate the occurrence of the above mutations in them.

Materials and Methods:

Total genomic DNA extracted from peripheral blood of 60 subjects with nonsyndromic cleft palate and cleft lip with or without cleft palate, and equal number of control healthy subjects were amplified with primers flanking exon 1 of ARHGAP29 gene and subjected to direct sequencing.

Results:

Sequencing analysis identified a nonsense mutation in exon 1 of ARHGAP29 that caused substitution of lysine to stop codon at codon position 32 in a subject with nonsyndromic cleft lip with cleft palate. The mutation, however, occurred in heterozygous condition. None of the other subjects carried mutation in this region.

Conclusion:

The study has thus identified a rare but novel truncation mutation in ARHGAP29 gene for the first time in nonsyndromic oral clefts.

Sirenomelia: a new type, showing VACTERL association with Thomas syndrome and a review of literature

Sirenomelia or "mermaid syndrome" is a rare congenital anomaly known since antiquity. This congenital anomaly is defined as a polymalformative syndrome that associates major muscle and skeleton abnormalities (unique lower limbs) with visceral abnormalities (unilateral or bilateral renal agenesis, anomalies of the abdominal vascularisation). This phenotype, typical of sirenomelia syndrome, may be more or less severe. The pathogenic mechanisms of this syndrome are still debated and its etiology remains unknown. We report here a new type of sirenomelia that we observed in a fetus belonging to the collection of the Department of Anatomy of Reims, which led us to perform a comprehensive review of the literature on the subject: this type has never been reported and cannot be classified according to the Stocker and Heifetz classification. Moreover, this case also presents a VACTERL association with Thomas syndrome.

Premaxillary characteristics in complete bilateral cleft lip and palate: A predictor for treatment outcome

Objectives:

The aim of the current study was to investigate how bilateral cleft lip and palate (BCLP) cases responded differently to presurgical orthopedics (PSO) and primary lip repair (LR) based on premaxillary characteristics. We suggest a clinically oriented descriptive classification for BCLP based on premaxillary characteristics.

Design and Setting:

A retrospective longitudinal comparative study where available records of all non-syndromic patients with complete BCLP attending the Cleft Clinic, affiliated to the Oral and Maxillofacial Surgery department, Ain-Shams University, Cairo, Egypt were assessed.

Sample Population and Methodology:

Twenty-two cases were collected over a 4-years period from 2008 to 2011 (15 boys and 7 girls). Model assessment was performed for serial models representing four stages of treatment; M1: Prior to start of PSO, M2: At the end of PSO, M3: One month after LR, M4: Three months after LR. The premaxillary and vomerine widths were measured on M1. Models (M1-M4) were assessed for changes in anteroposterior projection, anterior arch width, intercanine width and posterior arch width and results were statistically analyzed. Intra-and postoperative surgical findings during and after primary LR were recorded. The sample was divided into two groups based on the premaxillary size and characteristics; Group R: Rudimentary premaxilla and Group P: Prominent premaxilla.

Results:

There was a highly significant difference in premaxillary width between the two groups (P = 0.00), changes in anteroposterior projection of the premaxilla were significant one and three months after LR. Changes in maxillary anterior arch width, intercanine and posterior arch widths were non-significant between groups. Mean age difference between the two groups was only statistically significant at the stage of LR. Surgical differences were noted between the two groups. Postoperatively as compared to group R; group P showed more premaxillary bulge and show at rest, as well as more prolabial stretching. In addition, facial profile was more convex in group P.

Conclusion:

The two types of BCLP outlined in this study are different from several aspects, and hence management should be modified according to each case. This descriptive classification provides a useful tool for evaluation and planning of patients with BCLP.

Does the relationship between prenatal care and birth weight vary by oral clefts? evidence using South American and United States samples

OBJECTIVE

To evaluate if the association between prenatal care use and birth weight (BW) varies for infants with cleft lip and/or cleft palate (CL/P), classified into isolated and non-isolated forms, compared with unaffected infants.

STUDY DESIGN

The study employed 2 datasets. The first included a multi-country sample of 2405 infants with CL/P and 24046 infants without CL/P born in 1996-2007 in South America. The second was a sample of 2122 infants with CL/P and 297415 without CL/P from the United States 2004 natality dataset. Separate analyses were performed for the South American and United States samples. The association between prenatal care and BW was evaluated separately for isolated CL/P, non-isolated CL/P, and unaffected infants using regression models adjusting for several background characteristics.

RESULTS

Prenatal care was associated with improved BW for all infant groups, with greater BW increases for infants with CL/P particularly non-isolated forms. In the South American sample, BW increased by 108, 69, and 40 g on average per prenatal visit for infants with non-isolated CL/P, infants with isolated CL/P, and unaffected infants, respectively. In the United States sample, BW increased by 51, 21, and 16 g on average per prenatal visit for these infant groups, respectively.

CONCLUSIONS

Prenatal care was associated with larger BW increases for pregnancies complicated with CL/P, particularly non-isolated forms, compared with unaffected pregnancies. Given that reduced BW is a well-recognized comorbidity of CL/P, the findings highlight the importance of prenatal care for at-risk pregnancies as a tertiary-prevention intervention to reduce the health burden of CL/P.

Is missing maxillary lateral incisor in complete cleft lip and palate a product of genetics or local environment?

OBJECTIVE

To test the null hypothesis: Subjects with isolated complete unilateral cleft lip and palate (UCLP) show no differences in overall frequency of tooth agenesis (hypodontia), comparing a subsample with cleft-side maxillary lateral incisor (MxI2) agenesis to a subsample without cleft-side MxI2 agenesis. Findings could clarify the origins of cleft-side MxI2 agenesis.

MATERIALS AND METHODS

Tooth agenesis was identified from dental radiographs of 141 subjects with UCLP. The UCLP cohort was segregated into four categories according to the status and location of MxI2 in the region of the unilateral cleft: group M: subjects with one tooth, located on the mesial side of the alveolar cleft; group D: subjects with one tooth, located on the distal side of the alveolar cleft; group MD: subjects with two teeth present, one mesial and one distal to the cleft; and group ABS: subjects with lateral incisor absent (agenesis) in the cleft area.

RESULTS

The null hypothesis was rejected. Among UCLP subjects, there was a twofold increase (P < .0008) in overall frequency of tooth agenesis outside the cleft region in a subsample with cleft-side MxI2 agenesis (ABS), compared to a subsample presenting with no agenesis of the cleft-side MxI2 (M+D+MD).

CONCLUSIONS

Cleft-side MxI2 agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis.

The effects of oral clefts on hospital use throughout the lifespan

Background

Oral clefts are one of the most common birth defects worldwide. They require multiple healthcare interventions and add significant burden on the health and quality of life of affected individuals. However, not much is known about the long term effects of oral clefts on health and healthcare use of affected individuals. In this study, we evaluate the effects of oral clefts on hospital use throughout the lifespan.

Methods

We estimate two-part regression models for hospital admission and length of stay for several age groups up to 68 years of age. The study employs unique secondary population-based data from several administrative inpatient, civil registration, demographic and labor market databases for 7,670 individuals born with oral clefts between 1936 and 2002 in Denmark, and 220,113 individuals without oral clefts from a 5% random sample of the total birth population from 1936 to 2002.

Results

Oral clefts significantly increase hospital use for most ages below 60 years by up to 233% for children ages 0-10 years and 16% for middle age adults. The more severe cleft forms (cleft lip with palate) have significantly larger effects on hospitalizations than less severe forms.

Conclusions

The results suggest that individuals with oral clefts have higher hospitalization risks than the general population throughout most of the lifespan.

The effect of systematic pediatric care on neonatal mortality and hospitalizations of infants born with oral clefts

Background

Cleft lip and/or palate (CL/P) increase mortality and morbidity risks for affected infants especially in less developed countries. This study aimed at assessing the effects of systematic pediatric care on neonatal mortality and hospitalizations of infants with cleft lip and/or palate (CL/P) in South America.

Methods

The intervention group included live-born infants with isolated or associated CL/P in 47 hospitals between 2003 and 2005. The control group included live-born infants with CL/P between 2001 and 2002 in the same hospitals. The intervention group received systematic pediatric care between the 7^th and 28^th day of life. The primary outcomes were mortality between the 7^th and 28^th day of life and hospitalization days in this period among survivors adjusted for relevant baseline covariates.

Results

There were no significant mortality differences between the intervention and control groups. However, surviving infants with associated CL/P in the intervention group had fewer hospitalization days by about six days compared to the associated control group.

Conclusions

Early systematic pediatric care may significantly reduce neonatal hospitalizations of infants with CL/P and additional birth defects in South America. Given the large healthcare and financial burden of CL/P on affected families and the relatively low cost of systematic pediatric care, improving access to such care may be a cost-effective public policy intervention.

Trial Registration

ClinicalTrials.gov: NCT00097149

Retinoic acid drives aryl hydrocarbon receptor expression and is instrumental to dioxin-induced toxicity during palate development

BACKGROUND

Palate development depends on complex events and is very sensitive to disruption. Accordingly, clefts are the most common congenital malformations worldwide, and a connection is proposed with fetal exposure to toxic factors or environmental contaminants, such as dioxins. There is increasing evidence that dioxin interferes with all-trans-retinoic acid (atRA), a hormone-like signal derived from vitamin A, which plays an essential role during embryonic development. Although similarities have been described between dioxin-induced toxicity and the outcome of altered atRA signaling during palate development, their relationship needs to be clarified.

OBJECTIVES

We used a genetic approach to understand the interaction between atRA and dioxin and to identify the cell type targeted by dioxin toxicity during secondary palate formation in mice.

METHODS

We analyzed the phenotype of mouse embryos harboring an atRA-sensitive reporter transgene or bearing null mutations for atRA-synthesizing enzymes (RALDH) or atRA receptors (RAR) and maternally exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at gestation day 10.5.

RESULTS

We found that an intact atRA signal was required to enable TCDD to induce cleft palate. This mandatory atRA signal was generated through the activity of RALDH3 in the nasal epithelium and was transduced by RARγ (RARG) in the nasal mesenchyme, where it notably controlled aryl hydrocarbon receptor (Ahr) transcript levels. TCDD also did not alter the developmental pattern of atRA signaling during palate formation.

CONCLUSIONS

TCDD-induced alteration of secondary palate development in the mouse appears to depend on atRA signaling, which controls AHR expression. This mechanism is likely conserved throughout vertebrate evolution and may therefore be relevant in humans.

Parental age as a risk factor for non-syndromic oral clefts: a meta-analysis

OBJECTIVES

A meta-analysis was conducted to assess the relationship between parental age and the occurrence of non-syndromic oral clefts. The questions addressed if younger or older mothers and fathers have an increased risk of having a child with non-syndromic oral clefts.

DATA

Data from cohort studies, case-control, cross-sectional and prevalence studies in which the association between parental age and oral clefts was investigated were analysed. Only studies on oral clefts not associated with syndromes or other anomalies were considered.

SOURCES

An electronic literature search were conducted in Medline, Embase, LILACS, SciELO, SCOPUS and the Cochrane library databases to identify original research published until November 2010. References of the selected articles were also searched.

STUDY SELECTION

The initial database search identified 4623 citations and according to eligibility criteria 80 articles were submitted to quality assessment. In 13 studies measures of association could be extracted for meta-analysis.

CONCLUSION

Our findings suggest that fathers forty years of age or older had a 58% higher probability of having a child with cleft palate compared to those aged between 20 and 39 years. The probability of mothers aged between 35 and 39 years having a child with cleft palate was 20% higher in comparison with those between 20 and 29 years-old, whilst for those aged 40 years or more this probability was 28% higher compared to those aged between 20 and 29 years. Mothers aged 40 years or over were 1.56 times more likely to have a newborn with cleft lip with or without palate compared to those aged between 20 and 29 years. No evidence of association between early maternal and paternal age with occurrence of oral clefts was observed.

Dental anomalies in children born with clefts: a case-control study

OBJECTIVE

To determine the presence of specific patterns of dental defects in a group of individuals born with clefts.

DESIGN

Case-control.

SETTING

Nossa Senhora do Loreto Municipal Hospital and Federal University of Rio de Janeiro Pediatric Dentistry Clinics, Rio de Janeiro, Brazil.

PATIENTS

642 radiographic and clinical records were evaluated for 321 cases and 321 controls.

RESULTS

Individuals born with clefts presented considerably more dental anomalies in comparison with controls (p  =  .0001). The most frequent was tooth agenesis (n  =  53; p  =  .001), followed by supernumerary teeth (n  =  14; p  =  .11) and tooth malposition (n  =  11; p  =  .33). Regarding tooth agenesis, the upper lateral incisors were more frequently absent in the cleft group (31/86), and control individuals presented more agenesis of the mandibular second premolars (19/45).

CONCLUSIONS

The higher prevalence of dental anomalies, especially number anomalies, opposite the cleft area, in individuals born with cleft lip and/or palate is the most common associated dental anomaly outside the cleft area.

GENES AS INSTRUMENTS FOR STUDYING RISK BEHAVIOR EFFECTS: AN APPLICATION TO MATERNAL SMOKING AND OROFACIAL CLEFTS

This study uses instrumental variable (IV) models with genetic instruments to assess the effects of maternal smoking on the child's risk of orofacial clefts (OFC), a common birth defect. The study uses genotypic variants in neurotransmitter and detoxification genes relateded to smoking as instruments for cigarette smoking before and during pregnancy. Conditional maximum likelihood and two-stage IV probit models are used to estimate the IV model. The data are from a population-level sample of affected and unaffected children in Norway. The selected genetic instruments generally fit the IV assumptions but may be considered "weak" in predicting cigarette smoking. We find that smoking before and during pregnancy increases OFC risk substantially under the IV model (by about 4-5 times at the sample average smoking rate). This effect is greater than that found with classical analytic models. This may be because the usual models are not able to consider self-selection into smoking based on unobserved confounders, or it may to some degree reflect limitations of the instruments. Inference based on weak-instrument robust confidence bounds is consistent with standard inference. Genetic instruments may provide a valuable approach to estimate the "causal" effects of risk behaviors with genetic-predisposing factors (such as smoking) on health and socioeconomic outcomes.

Communication and cognition profiles in parents of children with nonsyndromic cleft lip and/or palate

The main aim of the study was to ascertain whether parents of children with nonsyndromic cleft lip and/or palate (P-CLP) perform differently than parents of children without CLP (P-control) on a nonword repetition (NWR) test. Given that children with CLP frequently demonstrate communication and cognitive difficulties, a link between NWR performance and group would lend support to a familial risk factor in nonsyndromic CLP. The NWR test, a well-documented assessment to identify language and cognitive impairment, was used, together with a parent questionnaire to gather demographic data and family history information on medical, communication, and/or cognitive difficulties for 260 parents. Group differences on NWR performance and family history of communication and cognition difficulties were not demonstrated. Also, no significant difference on NWR score was seen in the P-CLP group based on child's CLP type. Correlation analysis showed that having more years of schooling, English as the dominant language, living in private housing, and being in skilled occupations were positively correlated to NWR score. Controlling for these known background variables did not alter NWR performance between P-CLP and P-control, however, only years of schooling significantly and consistently predicted NWR performance. Having significantly fewer years of schooling in the P-CLP group could be suggestive of an increased risk of communication and cognitive difficulties these parents face, and the potential difficulties their children with CLP may encounter. These results may inform early and rigorous intervention strategies for children with CLP.

The mechanism of TGF-β signaling during palate development

Cleft palate, a malformation of the secondary palate development, is one of the most common human congenital birth defects. Palate formation is a complex process resulting in the separation of the oral and nasal cavities that involves multiple events, including palatal growth, elevation, and fusion. Recent findings show that transforming growth factor beta (TGF-β) signaling plays crucial roles in regulating palate development in both the palatal epithelium and mesenchyme. Here, we highlight recent advances in our understanding of TGF-β signaling during palate development.

Palate morphogenesis: current understanding and future directions

In the past, most scientists conducted their inquiries of nature via inductivism, the patient accumulation of "pieces of information" in the pious hope that the sum of the parts would clarify the whole. Increasingly, modern biology employs the tools of bioinformatics and systems biology in attempts to reveal the "big picture." Most successful laboratories engaged in the pursuit of the secrets of embryonic development, particularly those whose research focus is craniofacial development, pursue a middle road where research efforts embrace, rather than abandon, what some have called the "pedestrian" qualities of inductivism, while increasingly employing modern data mining technologies. The secondary palate has provided an excellent paradigm that has enabled examination of a wide variety of developmental processes. Examination of cellular signal transduction, as it directs embryogenesis, has proven exceptionally revealing with regard to clarification of the "facts" of palatal ontogeny-at least the facts as we currently understand them. Herein, we review the most basic fundamentals of orofacial embryology and discuss how functioning of TGFbeta, BMP, Shh, and Wnt signal transduction pathways contributes to palatal morphogenesis. Our current understanding of palate medial edge epithelial differentiation is also examined. We conclude with a discussion of how the rapidly expanding field of epigenetics, particularly regulation of gene expression by miRNAs and DNA methylation, is critical to control of cell and tissue differentiation, and how examination of these epigenetic processes has already begun to provide a better understanding of, and greater appreciation for, the complexities of palatal morphogenesis.

A metabonomic approach to analyze the dexamethasone-induced cleft palate in mice

Mice models are an important way to understand the relation between the fetus with cleft palate and changes of maternal biofluid. This paper aims to develop a metabonomics approach to analyze dexamethasone-induced cleft palate in pregnant C57BL/6J mice and to study the relationship between the change of endogenous small molecular metabolites in maternal plasma and the incidence of cleft palate. To do so, pregnant mice were randomly divided into two groups. The one group was injected with dexamethasone. On E17.5th day, the incident rates of cleft palate from embryos in two groups were calculated. The ¹H-NMR spectra from the metabolites in plasma in two groups was collected at same time. Then the data were analyzed using metabonomics methods (PCA and SIMCA). The results showed that the data from the two groups displayed distinctive characters, and the incidence of cleft palate were significantly different (P < .005). To conclude, this study demonstrates that the metabonomics approach is a powerful and effective method in detecting the abnormal metabolites from mother in the earlier period of embryos, and supports the idea that a change from dexamethasone induced in maternal metabolites plays an important role in the incidence of cleft palate.

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.

Diazepam effects on non-syndromic cleft lip with or without palate: epidemiological studies, clinical findings, genes and extracellular matrix

IMPORTANCE OF THE FIELD

This review analyses international studies investigating the combined genetic and environmental causes of cleft lip with or without cleft palate (CL/P) and describes successes and limitations in identifying underlying genetic and environmental factors. CL/P, the most common congenital facial malformation, is a major public health burden in terms of medical costs and emotional stress to patients and families. Because genetic and environmental factors determine risk of occurrence, CL/P has a complex, multifactor aetiology.

AREAS COVERED IN THIS REVIEW

English language reports from 1980 to 2010 were searched for in Medline, PubMed, Science Citation Index, textbooks and review articles on drugs and pregnancy. Key words were diazepam or benzodiazepine(s) combined with cleft lip, cleft palate, oral malformations, prenatal exposure, GABA, gene expression and extracellular matrix.

WHAT THE READER WILL GAIN

This review presents an updated assessment of the mutagenic and genotoxic effects of diazepam (DZ), one of the most commonly used benzodiazepines, on CL/P occurrence.

TAKE HOME MESSAGE

Data are divergent; more studies are needed for an in-depth picture of the effects of DZ during gestation on the child's development, particularly on orofacial clefts.

Microdeletion of chromosome 15q24.3-25.2 and orofacial clefting

We report a case of de novo microdeletion of 15q24.3-q25.2 in an infant with orofacial cleft and general hypotonia and suggest that this may be a critical region in orofacial development. In addition, this case highlights the usefulness of comparative genomic microarray in the evaluation of children with congenital anomalies with such defects.

Environmental exposures and development

PURPOSE OF REVIEW

Summarize recent studies exploring the relationship between paternal and maternal environmental exposures to chemicals before, at the time of and after conception to adverse developmental outcomes including preterm birth, death, structural and functional abnormalities and growth restriction.

RECENT FINDINGS

Recent studies have demonstrated that human pregnancy and development are vulnerable to environmental exposures of the father and mother to chemical, biological and physical agents. Exposures associated with adverse developmental outcomes include air and water pollution, chemicals in foods, occupational exposures, agricultural chemicals, metals, persistent and volatile organics. Developmental endpoints which are linked with these exposures include growth restriction, functional abnormalities, structural abnormalities, preterm delivery and death. Despite this general understanding we still have incomplete knowledge concerning most exposures and the biological interactions responsible for impaired development and preterm delivery.

SUMMARY

Whereas single genes and individual chemical exposures are responsible for some instances of adverse pregnancy outcome or developmental disease, gene-environment interactions are responsible for the majority. These gene-environment interactions may occur in the father, mother, placenta or fetus, suggesting that critical attention be given to maternal and paternal exposures and gene expression as they relate to the mode of action of the putative developmental toxicant both prior to and during pregnancy.

Syndromes of the first and second branchial arches, part 1: embryology and characteristic defects

A variety of congenital syndromes affecting the face occur due to defects involving the first and second BAs. Radiographic evaluation of craniofacial deformities is necessary to define aberrant anatomy, plan surgical procedures, and evaluate the effects of craniofacial growth and surgical reconstructions. High-resolution CT has proved vital in determining the nature and extent of these syndromes. The radiologic evaluation of syndromes of the first and second BAs should begin first by studying a series of isolated defects: CL with or without CP, micrognathia, and EAC atresia, which compose the major features of these syndromes and allow more specific diagnosis. After discussion of these defects and the associated embryology, we proceed to discuss the VCFS, PRS, ACS, TCS, Stickler syndrome, and HFM.

Disruption of the murine Ap2β1 gene causes nonsyndromic cleft palate

Development of the secondary palate in mammals is a complex process that can be easily perturbed, leading to the common and distressing birth defect cleft palate. Animal models are particularly useful tools for dissecting underlying genetic components of cleft palate. We describe a new cleft palate model resulting from a transgene insertion mutation. Transgene insertional mutagenesis disrupts the genomic organization and expression of the Ap2β1 gene located on chromosome 11. This gene encodes the β2-adaptin subunit of the heterotetrameric adaptor protein 2 complex involved in clathrin-dependent endocytosis. Homozygous cleft palate mutant mice express no Ap2β1 messenger RNA or β2-adaptin protein and die during the perinatal period. Heterozygous mice are phenotypically normal despite expressing diminished β2-adaptin messenger RNA and protein compared with wildtype. Remarkably, the paralogous β1-adaptin subunit of the adaptor protein 1 complex partially substitutes for the missing β2-adaptin in embryonic fibroblasts from homozygous mutant mice, resulting in assembly of reduced levels of an adaptor protein 2 complex bearing β1-adaptin. This variant adaptor protein 2 complex is, therefore, apparently capable of maintaining viability of the homozygous mutant embryos until birth but insufficient to support palatogenesis. Nonsyndromic cleft palate in an animal model is associated with disruption of the Ap2β1 gene.