Maternal transmission effects of the PAX genes among cleft case-parent trios from four populations

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

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

Integrating transcriptomics and genomics to identify fibroblast growth factor/receptor candidate genes for non-syndromic orofacial cleft in Chinese

OBJECTIVES

The objective of this study was to explore the relationship between fibroblast growth factor/receptor (FGF/FGFR) and non-syndromic orofacial cleft (NSOC) in individuals of Han Chinese.

DESIGN

Initially, we performed RNA-Seq between non-syndromic cleft lip only (NSCLO) or non-syndromic cleft palate only (NSCPO) and control groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were carried out to evaluate the functions of differentially expressed genes (DEGs) of FGF/FGFR. Then, we selected the most significant DEG FGFR2 and performed an association analysis in Chinese. Linkage disequilibrium (LD) and haplotype analyses were performed with HaploView and PLINK. Additional bioinformatics functional prediction for the notable single nucleotide polymorphisms was performed with HaploReg V4.1 and 3DSNP.

RESULTS

Finally, we identified 32 mRNAs related to FGF/FGFR via RNA-Seq and chose FGFR2 in the subsequent association analysis. Results indicated that the single nucleotide polymorphism (SNP) rs2288336 in FGFR2 contributed significantly to both non-syndromic cleft lip with or without cleft palate (NSCL/P) and NSCLO, with p values of 5.00E-05 (OR = 0.79, 95% CI: 0.70-0.88) and 1.38E-04 (OR = 0.76, 95% CI: 0.65-0.87), respectively. In addition, rs3793893 in FGFR2 was found to be associated with NSCLO, with a p value of 1.02E-04 (OR = 0.67, 95% CI: 0.55-0.82).

CONCLUSIONS

Our research demonstrated that FGFR2 is significantly more involved in NSOC than other FGF/FGFRs in Chinese and further identified rs2288336 and rs3793893 in FGFR2 associated with NSOC subtypes, which provide further evidence for the genetic etiology of NSOC in Han Chinese.

Genetic Analysis of the Single-Nucleotide Polymorphisms rs880810, rs545793, rs80094639, and rs13251901 in Nonsyndromic Oral Clefts: A Case–Parent Trio Study

Oral clefts, including cleft lip (CL), cleft palate (CP), and cleft lip and palate (CLP), are the most common types of congenital anomalies of the human face. Various genetic and environmental factors play a role in developing oral clefts. Several studies have shown the association of the PAX7 gene and the 8q24 region with these oral clefts in different populations worldwide. However, there are no reported studies on the possible connection between the PAX7 gene and the 8q24 region nucleotide variants and the risk of developing nonsyndromic oral clefts (NSOC) in the Indian population. Hence, this study aimed to test the possible association between PAX7 gene single-nucleotide polymorphisms (SNPs) rs880810, rs545793,rs80094639, and rs13251901 of the 8q24 region using a case-parent trio design. Forty case-parent trios were selected from the CLP center. Genomic DNA was isolated from the cases and their parents. The rs880810, rs545793, rs80094639, and rs13251901 were genotyped by the MassARRAY technique. PLINK software was used for statistical analysis. All the SNPs were tested for Hardy-Weinberg equilibrium. No statistical significance was found with any SNPs, as none of the genotyped SNPs showed a p -value of less than 0.05. Hence, the rs880810, rs545793, and rs80094639 of the PAX7 gene, and rs13251901 of the 8q24 region are not associated with NSOC in the Indian population.

Rare genetic variants in SEC24D modify orofacial cleft phenotypes

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

Integrated Analysis of the Association Between Variants at PAX7 and NSCL/P in the Han Population

OBJECTIVE

Paired box 7 (PAX7) has been considered as a candidate gene for non-syndromic cleft lip with or without palate (NSCL/P). However, there is no research for the XXX, and previous studies concentrated on limited variants. This study aimed to conduct sufficiently dense and powerful scans of variants at PAX7 and explored the roles of variants at PAX7 in NSCL/P among the XXX.

DESIGN

Targeted region sequencing was performed to thoroughly screen variations, followed by a two-phase association analysis. 159 NSCL/P cases and 542 controls were analyzed in phase 1. Then in phase 2, the validation study was performed using 1626 cases and 2255 controls. We also explored the roles of variants at PAX7 gene in NSCL/P subtypes. Additionally, indirect associations were found by calculating LD and haplotypes.

SETTING

The study was conducted in XXX.

PATIENTS, PARTICIPANTS

159 NSCL/P cases and 542 controls were analyzed in phase 1. Then in phase 2, the validation study was performed using 1626 cases and 2255 controls.

INTERVENTIONS

Blood samples were collected.

MAIN OUTCOME MEASURES

To explore the association analysis between variants at PAX7 and NSCL/P in XXX.

RESULTS

The results showed that rs2236810, rs114882979 and rs2236804 were significantly associated with NSCL/P, which were predicted to have regulatory functions. Besides, variants at PAX7 function differently in the NSCL/P subtypes. We also discovered a PAX7 missense variant, NM_001135254 p.A369 V (NM_002584.2:c.1106C > T).

CONCLUSIONS

In summary, we confirmed 3 SNPs at PAX7 were significantly associated with NSCL/P in XXX and identified a missense variant, NM_001135254 p.A369 V (NM_002584.2:c.1106C > T).

Maternal Transmission of the PAX7 Single Nucleotide Polymorphisms among Indian Cleft Trios

Cleft lip and/or cleft palate (CL/P) is one of the most common congenital anomalies of the human face with a complex etiology involving multiple genetic and environmental factors. Several studies have shown the association of the paired box 7 ( PAX7 ) gene with CL/P in different populations worldwide. However, the current literature reveals no reported case-parent trio studies to evaluate the association between the PAX7 gene and the risk of nonsyndromic cleft lip and/or palate (NSCL/P) in the Indian population. Hence, the purpose of this study was to assess the PAX7 gene single nucleotide polymorphisms (SNPs) in the etiology of NSCL/P among the Indian cleft trios. Forty Indian case-parent trios of NSCL/P were included. The cases and their parents' genomic DNA were extracted. The SNPs rs9439714, rs1339062, rs6695765, rs742071, and rs618941of the PAX7 gene were genotyped using the Agena Bio MassARRAY analysis. The allelic transmission disequilibrium test was performed using PLINK software while pair-wise linkage disequilibrium by the Haploview program. The SNP rs9439714 showed evidence of association ( p -value = 0.02, odds ratio = 3) with NSCL/P. Considering the parent-of-origin effects, the SNPs rs9439714 and rs618941 showed an excess maternal transmission of allele C at rs9439714 ( p -value = 0.05) and G allele at rs618941 ( p -value = 0.04). The results of the present study suggested that the SNPs rs9439714 and rs618941 showed an excess maternal transmission of alleles suggestive of the possible role of the PAX7 gene involvement in the etiology of NSCL/P in the Indian population.

Role of PAX7 Gene rs766325 and rs4920520 Polymorphisms in the Etiology of Non-syndromic Cleft Lip and Palate: A Genetic Study

Non-syndromic cleft lip and palate (NSCLP) is one of the most common birth defects in humans with an overall prevalence of ∼1 in 700 live births around the world. The etiology of NSCLP is complex involving multiple genes, environmental factors, and gene-to-gene interactions. Several genome-wide associations (GWA) studies have shown the association of the paired box 7 ( PAX7 ) gene in the etiology of cleft lip and palate in different populations worldwide. However, there are no reported studies on the association between the rs766325 and rs4920520 polymorphisms and the risk of developing NSCLP in the Indian population. Hence, the present study aimed to test for the probable association between rs766325 and rs4920520 polymorphisms among NSCLP Indian population using a case-parent trio design. Forty case-parent trios were selected from the cleft lip and palate center based on the inclusion and exclusion criteria. Genomic DNA was isolated from the cases and their parents. The rs766325 and rs4920520 polymorphisms of the PAX7 gene were analyzed for their association using the MassARRAY analysis. The statistical analysis was done using the PLINK software. The rs766325 and rs4920520 polymorphisms were tested for the Hardy–Weinberg equilibrium. None of the polymorphisms showed any statistical significance. Hence, the rs766325 and rs4920520 polymorphisms of the PAX7 gene were found to be not associated with NSCLP in the Indian case-parent trios.

Genome-Wide Scan for Parent-of-Origin Effects in a sub-Saharan African Cohort With Nonsyndromic Cleft Lip and/or Cleft Palate (CL/P)

OBJECTIVE

Nonsyndromic cleft lip and/or cleft palate (NSCL/P) have multifactorial etiology where genetic factors, gene-environment interactions, stochastic factors, gene-gene interactions, and parent-of-origin effects (POEs) play cardinal roles. POEs arise when the parental origin of alleles differentially impacts the phenotype of the offspring. The aim of this study was to identify POEs that can increase risk for NSCL/P in humans using a genome-wide dataset.

METHODS

The samples (174 case-parent trios from Ghana, Ethiopia, and Nigeria) included in this study were from the African only genome wide association studies (GWAS) that was published in 2019. Genotyping of individual DNA using over 2 million multiethnic and African ancestry-specific single-nucleotide polymorphisms from the Illumina Multi-Ethnic Genotyping Array v2 15070954 A2 (genome build GRCh37/hg19) was done at the Center for Inherited Diseases Research. After quality control checks, PLINK was employed to carry out POE analysis employing the pooled subphenotypes of NSCL/P.

RESULTS

We observed possible hints of POEs at a cluster of genes at a 1 mega base pair window at the major histocompatibility complex class 1 locus on chromosome 6, as well as at other loci encompassing candidate genes such as ASB18, ANKEF1, AGAP1, GABRD, HHAT, CCT7, DNMT3A, EPHA7, FOXO3, lncRNAs, microRNA, antisense RNAs, ZNRD1, ZFAT, and ZBTB16.

CONCLUSION

Findings from our study suggest that some loci may increase the risk for NSCL/P through POEs. Additional studies are required to confirm these suggestive loci in NSCL/P etiology.

A Novel PAX3 Variant in a Chinese Pedigree with Nonsyndromic Cleft Lip With or Without Palate

Objectives: Nonsyndromic cleft lip with or without palate (NSCL/P) is a common congenital orofacial defect, which is associated with severe disruption of orofacial development. The present study was designed to identify potential underlying gene variants in a Chinese pedigree with NSCL/P, in which the proband and the proband's father were affected. Methods: DNA was extracted from the participants' peripheral venous blood, and whole-exome sequencing was performed on the proband and the proband's parents. Results: After filtering, a paired box gene 3 (PAX3) missense variant (c.92C>G_p.Thr31Ser) was identified, which was verified by Sanger sequencing. This variant, which was not present in 113 unrelated healthy individuals or in a Chinese public database, may affect the transcription inhibition domain of the PAX3 protein. Conservation analysis and in silico predictions suggested that this variant may be evolutionarily conserved and potentially deleterious. In addition, it was reported that mice with PAX3 variants show cleft palates. Thus, the PAX3 missense variant (c.92C>G_p.Thr31Ser) is a candidate causative variant in this family. Conclusions: To the best of our knowledge, the present study is the first to report on a PAX3 variant in a pedigree with NSCL/P. The present study further suggests that PAX3 may be associated with CL/P etiology.

PAX7 gene polymorphism in muscular temporomandibular disorders as potentially related to muscle stem cells

Background

Temporomandibular disorders (TMD) are a group of painful and debilitating disorders, involving the masticatory muscles and/or the temporomandibular joint (TMJ). Chronic TMD pain can be associated with genetic changes in the key muscle development genes.

Objective

To evaluate the association between polymorphisms in the PAX7 (paired box 7) gene and masticatory myalgia in patients with temporomandibular disorders (TMD).

Materials and methods

This is a case-control study. Patients with TMD were divided into two groups: (a) presence of muscular TMD (n = 122) and (b) absence of muscular TMD (n = 49). Genomic DNA was obtained from saliva samples from all participants to allow for genotyping single nucleotide polymorphisms in PAX7 (rs766325 and rs6659735). Over-representation of alleles was tested using chi-square or Fisher’s exact tests. Values of p < 0.05 were considered to be statistically significant.

Results

Individuals without muscular TMD were less likely to have the PAX7 rs6659735 GG genotype (p = 0.03). No associations were found for PAX7 rs766325.

Conclusions

Alterations in PAX7 may influence muscular pathophysiology and individuals with TMD and the rs6659735 homozygous genotype (GG) are seemingly associated with muscular involvement of the disorder. No associations were found in the region rs766325.

Cleft Candidate Genes and Their Products in Human Unilateral Cleft Lip Tissue

Cleft lip and palate are common congenital pathologies that affect the human population worldwide. The formation of cleft lip is associated with multiple genes and their coded proteins, which regulate the development of craniofacial region, but the exact role of these factors is not always clear. The use of morphological studies for evaluation of human cleft-affected tissue has been limited because of insufficiency of available pathological material. The aim of this study was to detect and compare the immunohistochemical expression of cleft candidate gene coded proteins (DLX4, MSX2, HOXB3, SHH, PAX7, SOX3, WNT3A, and FOXE1) in the non-syndromic unilateral cleft lip patient tissue and control group tissue. A semiquantitative counting method was used to evaluate the tissue in biotin-streptavidin-stained slides. Statistically significant differences between the patient and control groups were found for the number of immunoreactive structures for SHH (p = 0.019) and FOXE1 (p = 0.011) in the connective tissue and SOX3 (p = 0.012) in the epithelium. Multiple statistically significant very strong and strong correlations were found between the immunoreactives in cleft-affected tissue. These significant differences and various correlations indicate that multiple morphopathogenetic pathways are possibly involved in unilateral cleft lip pathogenesis. Therefore, we further discuss these possible interactions.

Case-Parent Trio Studies in Cleft Lip and Palate

Cleft lip with or without cleft palate (CL/P) is one of the most common congenital malformations in humans involving various genetic and environmental risk factors. The prevalence of CL/P varies according to geographical location, ethnicity, race, gender, and socioeconomic status, affecting approximately 1 in 800 live births worldwide. Genetic studies aim to understand the mechanisms contributory to a phenotype by measuring the association between genetic variants and also between genetic variants and phenotype population. Genome-wide association studies are standard tools used to discover genetic loci related to a trait of interest. Genetic association studies are generally divided into two main design types: population-based studies and family-based studies. The epidemiological population-based studies comprise unrelated individuals that directly compare the frequency of genetic variants between (usually independent) cases and controls. The alternative to population-based studies (case–control designs) includes various family-based study designs that comprise related individuals. An example of such a study is a case–parent trio design study, which is commonly employed in genetics to identify the variants underlying complex human disease where transmission of alleles from parents to offspring is studied. This article describes the fundamentals of case–parent trio study, trio design and its significances, statistical methods, and limitations of the trio studies.

Genetic Factors in Nonsyndromic Orofacial Clefts

Orofacial clefts (OFCs) are the most common congenital birth defects in humans and immediately recognized at birth. The etiology remains complex and poorly understood and seems to result from multiple genetic and environmental factors along with gene-environment interactions. It can be classified into syndromic (30%) and nonsyndromic (70%) clefts. Nonsyndromic OFCs include clefts without any additional physical or cognitive deficits. Recently, various genetic approaches, such as genome-wide association studies (GWAS), candidate gene association studies, and linkage analysis, have identified multiple genes involved in the etiology of OFCs. This article provides an insight into the multiple genes involved in the etiology of OFCs. Identification of specific genetic causes of clefts helps in a better understanding of the molecular pathogenesis of OFC. In the near future, it helps to provide a more accurate diagnosis, genetic counseling, personalized medicine for better clinical care, and prevention of OFCs.

[Exploring parent-of-origin effects for non-syndromic cleft lip with or without cleft palate on PTCH1, PTCH2, SHH, SMO genes in Chinese case-parent trios]

OBJECTIVE

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect, affecting 1.4 per 1 000 live births, and multiple genetic and environmental risk factors influencing its risk. All the known genetic risk factors accounted for a small proportion of the heritability. Several authors have suggested parent-of-origin effects (PoO) may play an important role in the etiology of this complex and heterogeneous malformation. To clarify the genetic association between PTCH1, PTCH2, SHH and SMO in hedgehog (HH) pathway and NSCL/P, as well as testing for potential PoO effects in Chinese case-parent trios.

METHODS

We tested for transmission disequilibrium tests (TDT) and PoO effects using 83 common single nucleotide polymorphic (SNP) markers of HH pathway genes from 806 NSCL/P case-parent trios. These trios were drawn from an international consortium established for a genome-wide association studies (GWAS) of non-syndromic oral clefts of multiple ethnicities. DNA samples were collected from each trio. Single marker and haplotype based analysis were performed both in TDT tests and PoO effects. SNPs were excluded if they (ⅰ) had a call rate of < 95%, (ⅱ) had a minor allele frequency (MAF) of < 0.05, (ⅲ) had Mendelian errors over all trios of >5%, (ⅳ) had a genotype distribution in the parents that deviated from the Hardy-Weinberg equilibrium (HWE) (P < 0.000 1). The process was done using Plink (version 1.07, <a href="http://pngu.mgh.harvard.edu/~purcell/plink/data.shtml" target="_blank">http://pngu.mgh.harvard.edu/~purcell/plink/data.shtml</a>). TDT test was performed in Plink v1.07. A log-linear model was used to explore PoO effects using Haplin v6.2.1 as implemented in R package v3.4.2. Significance level was assessed using the Bonferroni correction.

RESULTS

A total of 18 SNPs were dropped due to low MAF, thus leaving 65 SNPs available for the analysis. Thus the Bonferroni threshold was 7.7×10^-4 (0.05/65). Nominal significant association with NSCL/P was found at a SNP (rs4448343 in PTCH1, P=0.023) and six haplotypes (rs10512249-rs4448343, rs1461208-rs7786445, rs10512249-rs4448343, rs16909865-rs10512249-rs4448343, rs1461208-rs7786445-rs12698335, and rs288756-rs288758-rs1151790, P < 0.05). A total of six haplotypes (rs288765-rs1233563, rs12537550-rs11765352, rs872723-rs288765-rs1233563, rs288765-rs1233563-rs288756, rs6459952-rs12537550-rs11765352, and rs12537550-rs11765352-rs6971211) showed PoO effect (P < 0.05). None of the results remained significant after the Bonferroni correction (P>7.7×10^-4).

CONCLUSION

Neither significant association between SNPs within HH pathway and the risk of NSCL/P nor PoO effects was seen in this study.

Association Between Nonsyndromic Cleft Lip and Palate and 2 Polymorphic Loci: A Meta-Analysis

OBJECTIVES

The relationship between Noggin (NOG) and methylenetetrahydrofolate reductase and nonsyndromic cleft lip and palate (NSCLP) has been reported participate in craniofacial development but need further evidence. To indicate the susceptibility between the 2 genes and NSCLP, rs227731 and rs1801131 polymorphisms were included in the present research. This research may provide some genetic clues for disease detection and surveillance.

DESIGN

Seventeen studies including 4023 cases and 5691 controls were provided for meta-analysis, and odds ratio (OR) with 95% CI were obtained to estimate NSCLP risk.

RESULTS

Our analysis suggested potential association of rs227731C on increasing the risk of NSCLP in the Caucasian group and total group but not Asian group under all models: allele (OR = 1.45, 95% CI = 1.21-1.75, P < .0001), homozygote (OR = 2.03, 95% CI = 1.42-2.90, P < .0001), heterozygote (OR = 1.44, 95% CI = 1.19-1.73, P = .0001), dominant (OR = 1.61, 95% CI = 1.27-2.04, P < .0001), and recessive models (OR = 1.63, 95% CI = 1.25-2.12, P = .0003). Besides, increased risk is related to rs1801131 in Asian group under 3 models: allele (OR = 1.24, 95% CI = 1.06-1.44, P = .006), heterozygote (OR = 1.24, 95% CI = 1.02-1.52, P = .03), and dominant models (OR = 1.29, 95% CI = 1.06-1.56, P = .009).

CONCLUSIONS

Our analysis indicates polymorphisms rs227731 and rs1801131 are associated with NSCLP, with predominance of different ethnic group and deepen understanding of NSCLP.

Variants in miRNA regulome and their association with the risk of nonsyndromic orofacial clefts

Aim: To investigate the associations between single nucleotide polymorphisms (SNPs) in miRNA regulome and nonsyndromic orofacial clefts. Materials & methods: The associations were evaluated by logistic regression model in stage I (504 cases and 455 controls) and stage II (1500 cases and 1386 controls). Functional experiments including luciferase activity assay, cell apoptosis and proliferation, serum miRNA expression, and mouse embryo RNA sequencing were performed. Results: Rs3830766 in the enhancer of hsa-miR-4260 was associated with cleft lip only (CLO) and enhancer activity. Hsa-miR-4260 expression decreased in the serum of CLO. Overexpression of miR-4260 inhibited cell proliferation and promoted cell apoptosis. UBB was the target gene of hsa-miR-4260. Conclusion: Rs3830766 in the hsa-miR-4260 enhancer that can interact with UBB was relevant to CLO.

PAX7 nucleotide variants and the risk of non-syndromic orofacial clefts in the Polish population

OBJECTIVE

The etiology of non-syndromic cleft lip with or without cleft palate (nsCL/P) is multifactorial, heterogeneous, and still not completely understood. The aim of the present study was to examine the associations between common and rare PAX7 nucleotide variants and the risk of this common congenital anomaly in a Polish population.

SUBJECTS AND METHODS

Eight top nsCL/P-associated PAX7 variants identified in our cleft genome-wide association study (GWAS) were selected for replication analysis in an independent group of patients and controls (n = 247 and n = 445, respectively). In addition, mutation screening of the PAX7 protein-coding region was conducted.

RESULTS

Analysis of the pooled data from the GWAS and replication study confirmed that common PAX7 nucleotide variants are significantly associated with the increased risk of nsCL/P. The strongest individual variant was rs1339062 (c.586 + 15617T > C) with a p-value = 2.47E-05 (OR = 1.4, 95%CI: 1.20-1.64). Sequencing analysis identified a novel synonymous PAX7 substitution (c.87G > A, p.Val29Val) in a single patient with nsCLP. This transition located in the early exonic position was predicted to disrupt potential splice enhancer elements.

CONCLUSION

Our study confirmed that PAX7 is a strong candidate gene for nsCL/P. Nucleotide variants of this gene contribute to the etiology of nsCL/P in the homogenous Polish population.

Assessment of differentially expressed plasma microRNAs in nonsyndromic cleft palate and nonsyndromic cleft lip with cleft palate

Plasma microRNAs (miRNAs) have recently emerged as a new class of regulatory molecules that influence many biological functions. However, the expression profile of plasma microRNAs in nonsyndromic cleft palate (NSCP) or nonsyndromic cleft lip with cleft palate (NSCLP) remains poorly investigated. In this study, we used Agilent human miRNA microarray chips to monitor miRNA levels in three NSCP plasma samples (mixed as the CP group), three NSCLP plasma samples (mixed as the CLP group) and three normal plasma samples (mixed as the Control group). Six selected plasma miRNAs were validated in samples from an additional 16 CP, 33 CLP and 8 healthy children using qRT-PCR. Using Venn diagrams, distinct and overlapping dysregulated miRNAs were identified. Their respective target genes were further assessed using gene ontology and pathway analysis. The results show that distinct or overlapping biological processes and signalling pathways were involved in CP and CLP. Our study showed that the common key gene targets reflected functional relationships to the Notch, Wnt, phosphatidylinositol and Hedgehog signalling pathways. Further studies should examine the mechanism of the potential target genes, which may provide new avenues for future clinical prevention and therapy.

Association between PAX7 and NTN1 gene polymorphisms and nonsyndromic orofacial clefts in a northern Chinese population

BACKGROUND

Nonsyndromic orofacial clefts (NSOC) are the most common orofacial congenital defect with a complex etiology. Genome-wide association studies have identified paired box protein 7 (PAX7) and netrin-1 (NTN1) as candidate susceptibility genes for NSOC in both European and Asian populations. Here, possible associations between single-nucleotide polymorphisms (SNPs) in or near PAX7 and NTN1 were investigated in relation to risk of NSOC in a northern Chinese population.

METHODS

A total of 602 individuals with NSOC and 510 controls were recruited from northern China. Polymerase chain reaction-ligation detection reactions were used to analyze 4 SNPs (rs742071, rs6659735, rs766325, and rs4920520) of PAX7 and 2 SNPs (rs9904526 and rs9788972) of NTN1. Investigations of polymorphisms and risk of NSOC were conducted by using the PLINK software.

RESULTS

NTN1 rs9788972 AG was found to be associated with an increased risk of NSOC compared to the GG homozygous genotype (OR = 1.43, 95% CI = 1.11-1.86, P = .006). When the multifactor dimensionality reduction method was applied, NTN1 rs9788972 still exhibited an increased risk for NSOC (P = .008). In contrast, SNPs in PAX7 were not associated with any increased risk of NSOC.

CONCLUSION

NTN1 rs9788972 is identified as a risk locus for NSOC susceptibility in a northern Chinese population.

Analysis of susceptibility polymorphisms for nonsyndromic cleft lip with or without cleft palate in the Brazilian population

BACKGROUND

Although genome-wide association studies have identified several susceptibility loci for nonsyndromic cleft lip with or without cleft palate (NSCL/P) in populations around the world, the role of most loci is unknown in the highly heterogeneous Brazilian population.

METHODS

To determine the association of 7 markers that showed genome-wide significant association in Brazilians with NSCL/P, we conducted a structured association study conditioned upon the individual ancestry proportions to evaluate markers at 1p36 (rs742071), 2p21 (rs7590268), 3p11.1 (rs7632427), 8q21.3 (rs12543318), 13q31.1 (rs8001641), 15q22.2 (rs1873147), and 17q22 (rs227731) in 505 patients with NSCL/P and 594 healthy controls recruited from 2 different geographical regions of Brazil. The polymorphisms were genotyped by TaqMan 5'-exonuclease allelic discrimination assay, and each sample was independently typed for 40 biallelic short insertion/deletion markers to characterize the genomic ancestry.

RESULTS

After Bonferroni correction for multiple tests, significant associations with NSCL/P were observed for rs742071, rs1873147, and rs227731. However, the frequency of the risk alleles varied between the geographical regions, according to the proportions of European and African genomic ancestry. The group enriched by European ancestry showed significant association with rs227731 (p = 0.001), whereas the group with high African ancestry was significantly associated with rs1873147 polymorphism (p = 0.005). The significant association with rs742071 was only detected in the combined sample (p = 0.005).

CONCLUSION

The findings of the present study revealed the associations of 1p36 (rs742071), 15q22 (rs1873147), and 17p22 (rs227731) with NSCL/P in the Brazilian population, and further confirmed that the genetic heterogeneity of NSCL/P may be related to the different ethnic background of the affected individuals.

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

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

Exploratory genotype-phenotype correlations of facial form and asymmetry in unaffected relatives of children with non-syndromic cleft lip and/or palate

Family relatives of children with nonsyndromic cleft lip with or without cleft palate (NSCL/P) who presumably carry a genetic risk yet do not manifest overt oral clefts, often present with distinct facial morphology of unknown genetic etiology. This study investigates distinct facial morphology among unaffected relatives and examines whether candidate genes previously associated with overt NSCL/P and left-right body patterning are correlated with such facial morphology. Cases were unaffected relatives of individuals with NSCL/P (n = 188) and controls (n = 194) were individuals without family history of NSCL/P. Cases and controls were genotyped for 20 SNPs across 13 candidate genes for NSCL/P (PAX7, ABCA4-ARHGAP29, IRF6, MSX1, PITX2, 8q24, FOXE1, TGFB3 and MAFB) and left-right body patterning (LEFTY1, LEFTY2, ISL1 and SNAI1). Facial shape and asymmetry phenotypes were obtained via principal component analyses and Procrustes analysis of variance from 32 coordinate landmarks, digitized on 3D facial images. Case-control comparisons of phenotypes obtained were performed via multivariate regression adjusting for age and gender. Phenotypes that differed significantly (P < 0.05) between cases and controls were regressed on the SNPs one at a time. Cases had significantly (P < 0.05) more profile concavity with upper face retrusion, upturned noses with obtuse nasolabial angles, more protrusive chins, increased lower facial heights, thinner and more retrusive lips and more protrusive foreheads. Furthermore, cases showed significantly more directional asymmetry compared to controls. Several of these phenotypes were significantly associated with genetic variants (P < 0.05). Facial height and width were associated with SNAI1. Midface antero-posterior (AP) projection was associated with LEFTY1. The AP position of the chin was related to SNAI1, IRF6, MSX1 and MAFB. The AP position of the forehead and the width of the mouth were associated with ABCA4-ARHGAP29 and MAFB. Lastly, facial asymmetry was related to LEFTY1, LEFTY2 and SNAI1. This study demonstrates that, genes underlying lip and palate formation and left-right patterning also contribute to facial features characteristic of the NSCL/P spectrum.

Genetics of cleft lip and cleft palate

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

SNPs and interaction analyses of IRF6, MSX1 and PAX9 genes in patients with non‑syndromic cleft lip with or without palate

Non‑syndromic cleft lip with or without cleft palate (NSCL/P) is a common congenital deformity, often associated with missing or deformed teeth. The genes interferon regulatory factor 6 (IRF6), muscle segment homeobox 1 (MSX1) and paired box gene 9 (PAX9) are important for the development of the maxillofacial region and dentition. The aim of this study was to explore how genetic variations in IRF6, MSX1 and PAX9, as well as gene‑gene interactions, are associated with NSCL/P. We investigated 9 IRF6 tag single nucleotide polymorphisms (SNPs), 2 MSX1 tag SNPs and 8 PAX9 tag SNPs selected from HapMap data from the Chinese population. The SNPs were examined for associations with NSCL/P in 204 patients and 226 controls. The results demonstrated a significant association between NSCL/P and rs2073485, rs2235371, rs2236909 and rs861020 in the IRF6 gene, and haplotype analysis supported these findings. A marginally significant difference was observed in the NSCL/P group for rs17176643 in the PAX9 gene compared to the control group. The results of gene‑gene interaction analyses also indicated that the combination of rs2073485, rs2235371 or rs2236909 in IRF6 and rs17176643 in PAX9, increased the risk of NSCL/P. Thus, our study provided additional understanding of IRF6 variations in patients with NSCL/P and suggested that interactions between the IRF6 and PAX9 genes are potentially important for susceptibility to NSCL/P.

Corpus callosum shape is altered in individuals with nonsyndromic cleft lip and palate

Individuals with nonsyndromic cleft lip with or without cleft palate (CL/P) have altered brain structure compared with healthy controls. Preliminary evidence suggests that the corpus callosum may be dysmorphic in orofacial clefting; however, this midline brain structure has not been systematically assessed in this population. The goal of the present study was to carry out a morphometric assessment of the corpus callosum and its relationship to cognitive performance in a well-characterized patient cohort with orofacial cleft. Midline brain images were obtained from previously collected MRI scans of 24 CL/P subjects and 40-adult-male controls. Eight landmarks on the corpus callosum were digitized on each image and their x,y coordinate locations saved. A geometric morphometrics analysis was applied to the landmark coordinate data to test for shape differences across groups. The relationship between corpus callosum shape and IQ was explored with nonparametric correlation coefficients. Results revealed significant differences in mean corpus callosum shape between CL/P cases and controls (P = 0.029). The CL/P corpus callosum was characterized by increased overall convexity resulting from a superior and posterior displacement. Within CL/P cases, increased corpus callosum shape dysmorphology was moderately correlated with reduced performance IQ (r = 0.546). These results provide additional evidence that midline brain changes may be an important part of the orofacial cleft phenotype.

Genome-wide approaches (GWA) in oral and craniofacial diseases research

Oral Diseases (2012) Underlying molecular genetic mechanisms of diseases can be deciphered with unbiased strategies using recently developed technologies enabling genome-wide scale investigations. These technologies have been applied in scanning for genetic variations, gene expression profiles, and epigenetic changes for oral and craniofacial diseases. However, these approaches as applied to oral and craniofacial conditions are in the initial stages, and challenges remain to be overcome, including analysis of high throughput data and their interpretation. Here, we review methodology and studies using genome-wide approaches in oral and craniofacial diseases and suggest future directions.

Resequencing of VAX1 in patients with nonsyndromic cleft lip with or without cleft palate

BACKGROUND

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common of all congenital anomalies, and has a multifactorial etiology involving both environmental and genetic factors. Recent genome-wide association studies (GWAS) identified strong association between a locus on chromosome 10q25.3 and NSCL/P in European samples. One gene at 10q25.3, the ventral anterior homeobox 1 (VAX1) gene, is considered a strong candidate gene for craniofacial malformations. The purpose of the present study was to provide further evidence that VAX1 is the causal gene at the 10q25.3 locus through identification of an excess of rare mutations in patients with NSCL/P.

METHODS

The 5'UTR, complete coding regions, and adjacent splice sites of the two known VAX1 isoforms were sequenced in 384 patients with NSCL/P and 384 controls of Central European descent. Observed variants were investigated with respect to familial cosegregation or de novo occurrence, and in silico analyses were performed to identify putative effects on the transcript or protein level.

RESULTS

Eighteen single-base variants were found, 15 of them rare and previously unreported. In the long VAX1 isoform, predicted functionally relevant variants were observed more often in NSCL/P cases, although this difference was not significant (p = 0.17). Analysis of family members demonstrated incomplete cosegregation in most pedigrees.

CONCLUSION

Our data do not support the hypothesis that highly penetrant rare variants in VAX1 are a cause of NSCL/P. To determine whether VAX1 is the causative gene at 10q25.3 further research, in particular into the biologic function of its long isoform, is warranted. Birth Defects Research (Part A), 2012.

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

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

Genome-wide meta-analyses of nonsyndromic cleft lip with or without cleft palate identify six new risk loci

We have conducted the first meta-analyses for nonsyndromic cleft lip with or without cleft palate (NSCL/P) using data from the two largest genome-wide association studies published to date. We confirmed associations with all previously identified loci and identified six additional susceptibility regions (1p36, 2p21, 3p11.1, 8q21.3, 13q31.1 and 15q22). Analysis of phenotypic variability identified the first specific genetic risk factor for NSCLP (nonsyndromic cleft lip plus palate) (rs8001641; P(NSCLP) = 6.51 × 10(-11); homozygote relative risk = 2.41, 95% confidence interval (CI) 1.84-3.16).

Genome wide study of maternal and parent-of-origin effects on the etiology of orofacial clefts

We performed a genome wide association analysis of maternally-mediated genetic effects and parent-of-origin (POO) effects on risk of orofacial clefting (OC) using over 2,000 case-parent triads collected through an international cleft consortium. We used log-linear regression models to test individual SNPs. For SNPs with a P-value <10(-5) for maternal genotypic effects, we also applied a haplotype-based method, TRIMM, to extract potential information from clusters of correlated SNPs. None of the SNPs were significant at the genome wide level. Our results suggest neither maternal genome nor POO effects play major roles in the etiology of OC in our sample. This finding is consistent with previous genetic studies and recent population-based cohort studies in Norway and Denmark, which showed no apparent difference between mother-to-offspring and father-to-offspring recurrence of clefting. We, however, cannot completely rule out maternal genome or POO effects as risk factors because very small effects might not be detectable with our sample size, they may influence risk through interactions with environmental exposures or may act through a more complex network of interacting genes. Thus, the most promising SNPs identified by this study may still be worth further investigation.

Male and female differential reproductive rate could explain parental transmission asymmetry of mutation origin in Hirschsprung disease

Hirschsprung disease (HSCR, aganglionic megacolon) is a complex and heterogeneous disease with an incidence of 1 in 5000 live births. Despite the multifactorial determination of HSCR in the vast majority of cases, there is a monogenic subgroup for which private rare RET coding sequence mutations with high penetrance are found (45% of HSCR familial cases). An asymmetrical parental origin is observed for RET coding sequence mutations with a higher maternal inheritance. A parent-of-origin effect is usually assumed. Here we show that a differential reproductive rate for males and females also leads to an asymmetrical parental origin, which was never considered as a possible explanation till now. In the case of HSCR, we show a positive association between penetrance of the mutation and parental transmission asymmetry: no parental transmission asymmetry is observed in sporadic RET CDS mutation carrier cases for which penetrance of the mutation is low, whereas a parental transmission asymmetry is observed in affected sib-pairs for which penetrance of the mutation is higher. This allows us to conclude that the explanation for this parental asymmetry is that more severe mutations have resulted in a differential reproductive rate between male and female carriers.

VAX1 mutation associated with microphthalmia, corpus callosum agenesis, and orofacial clefting: the first description of a VAX1 phenotype in humans

Vax1 and Vax2 have been implicated in eye development and the closure of the choroid fissure in mice and zebrafish. We sequenced the coding exons of VAX1 and VAX2 in 70 patients with anophthalmia/microphthalmia (A/M). In VAX1, we observed homozygosity for two successive nucleotide substitutions c.453G>A and c.454C>A, predicting p.Arg152Ser, in a proband of Egyptian origin with microphthalmia, small optic nerves, cleft lip/palate, and corpus callosum agenesis. This mutation affects an invariant residue in the homeodomain of VAX1 and was absent from 96 Egyptian controls. It is likely that the mutation results in a loss of function, as the mutation results in a phenotype similar to the Vax1 homozygous null mouse. We did not identify any mutations in VAX2. This is the first description of a phenotype associated with a VAX1 mutation in humans and establishes VAX1 as a new causative gene for A/M.

Contribution of 6p24 to non-syndromic cleft lip and palate in a Malay population: association of variants in OFC1

Non-syndromic cleft lip, with or without cleft palate, is a heterogeneous, complex disease with a high incidence in the Asian population. Several association studies have been done on cleft candidate genes, but no reports have been published thus far on the Orofacial Cleft 1 (OFC1) genomic region in an Asian population. This study investigated the association between the OFC1 genomic region and non-syndromic cleft lip with or without cleft palate in 90 Malay father-mother-offspring trios. Results showed a preferential over-transmission of a 101-bp allele of marker D6S470 in the allele- and haplotype-based transmission disequilibrium test (TDT), as well as an excess of maternal transmission. However, no significant p-value was found for a maternal genotype effect in a log-linear model, although single and double doses of the 101-bp allele showed a slightly increased cleft risk (RR = 1.37, 95% CI, 0.527-3.4, p-value = 0.516). Carrying two copies of the 101-bp allele was significantly associated with an increased cleft risk (RR = 2.53, 95% CI, 1.06-6.12, p-value = 0.035). In conclusion, we report evidence of the contribution of the OFC1 genomic region to the etiology of clefts in a Malay population.

Analysis of early human neural crest development

The outstanding migration and differentiation capacities of neural crest cells (NCCs) have fascinated scientists since Wilhelm His described this cell population in 1868. Today, after intense research using vertebrate model organisms, we have gained considerable knowledge regarding the origin, migration and differentiation of NCCs. However, our understanding of NCC development in human embryos remains largely uncharacterized, despite the role the neural crest plays in several human pathologies. Here, we report for the first time the expression of a battery of molecular markers before, during, or following NCC migration in human embryos from Carnegie Stages (CS) 12 to 18. Our work demonstrates the expression of Sox9, Sox10 and Pax3 transcription factors in premigratory NCCs, while actively migrating NCCs display the additional transcription factors Pax7 and AP-2alpha. Importantly, while HNK-1 labels few migrating NCCs, p75(NTR) labels a large proportion of this population. However, the broad expression of p75(NTR) - and other markers - beyond the neural crest stresses the need for the identification of additional markers to improve our capacity to investigate human NCC development, and to enable the generation of better diagnostic and therapeutic tools.

FOXE1 association with both isolated cleft lip with or without cleft palate, and isolated cleft palate

Nonsyndromic orofacial clefts are a common complex birth defect caused by genetic and environmental factors and/or their interactions. A previous genome-wide linkage scan discovered a novel locus for cleft lip with or without cleft palate (CL/P) at 9q22-q33. To identify the etiologic gene, we undertook an iterative and complementary fine mapping strategy using family-based CL/P samples from Colombia, USA and the Philippines. Candidate genes within 9q22-q33 were sequenced, revealing 32 new variants. Concurrently, 397 SNPs spanning the 9q22-q33 2-LOD-unit interval were tested for association. Significant SNP and haplotype association signals (P = 1.45E - 08) narrowed the interval to a 200 kb region containing: FOXE1, C9ORF156 and HEMGN. Association results were replicated in CL/P families of European descent and when all populations were combined the two most associated SNPs, rs3758249 (P = 5.01E - 13) and rs4460498 (P = 6.51E - 12), were located inside a 70 kb high linkage disequilibrium block containing FOXE1. Association signals for Caucasians and Asians clustered 5' and 3' of FOXE1, respectively. Isolated cleft palate (CP) was also associated, indicating that FOXE1 plays a role in two phenotypes thought to be genetically distinct. Foxe1 expression was found in the epithelium undergoing fusion between the medial nasal and maxillary processes. Mutation screens of FOXE1 identified two family-specific missense mutations at highly conserved amino acids. These data indicate that FOXE1 is a major gene for CL/P and provides new insights for improved counseling and genetic interaction studies.