A multicentric association study between 39 genes and nonsyndromic cleft lip and palate in a Brazilian population

Ethnic Differences in the Brazilian Population Influence the Impact of BMP4 Genetic Variants on Susceptibility of Nonsyndromic Orofacial Clefts

OBJECTIVE

The study evaluated the association of BMP4 tag-SNPs and SNP-SNP interactions involving genes active by BMP4 pathway during craniofacial development in the susceptibility of nonsyndromic orofacial clefts (NSOC) in the Brazilian population.

DESIGN

Case-control study.

SETTING

Brazilian Oral Cleft Group.

PARTICIPANTS

The study included 881 healthy controls and 800 patients with different types of NSOC: 232 with cleft lip only (NSCLO), 568 with cleft lip and palate (NSCLP), and 274 with cleft palate only (NSCPO).

INTERVENTIONS

The genomic DNA was genotyped with allelic discrimination assays for five BMP4 tag-SNPs (rs11623717, rs17563, rs2071047, rs2761887 and rs4898820), and analyzed their allelic and genotypic associations using multiple logistic regression. The interactions of these variants with genes involved in the BMP4 signaling pathway, including FGFR1, GREM1, NOG, VAX1 and the 4p16.2 locus, were explored.

MAIN OUTCOME MEASURES

BMP4 variants in the NSOC risk.

RESULTS

Although only nominal p values were identified when the whole sample was considered, subgroup analysis including the patients with high African genomic ancestry showed significant associations of rs2761887 with risk for nonsyndromic cleft lip with or without cleft palate (NSCL  ±  P)[(ORhom: 2.16; 95% CI: 1.21-3.85; p  =  0.01) and (ORrec: 2.05; 95% CI: 1.21-3.47; p  =  0.006)]. Thirteen significant SNP-SNP interactions involving BMP4 and the SNPs at FGFR1, GREM1, NOG and VAX1 and at locus 4p16.2 for increased risk of NSCL  ±  P were identified.

CONCLUSIONS

Our results demonstrate an increased risk of NSCL  ±  P in Brazilian individuals with enrichment of African ancestry in the presence of the BMP4 rs2762887 polymorphism, and reveal relevant genetic contribution of SNP-SNP epistatic interactions involving BMP4 variants to NSCL  ±  P risk.

Molecular investigation in individuals with orofacial clefts and microphthalmia-anophthalmia-coloboma spectrum

This study describes genomic findings among individuals with both orofacial clefts (OC) and microphthalmia/anophthalmia/coloboma (MAC) recorded in the Brazilian Database on Craniofacial Anomalies (BDCA). Chromosomal microarray analysis (CMA) and Whole Exome Sequencing (WES) were performed in 17 individuals with OC-MAC. Clinical interpretation of molecular findings was based on data available at the BDCA and on re-examination. No copy number variants (CNVs) classified as likely pathogenic or pathogenic were detected by CMA. WES allowed a conclusive diagnosis in six individuals (35.29%), two of them with variants in the CHD7 gene, and the others with variants in the TFAP2A, POMT1, PTPN11, and TP63 genes with the following syndromes: CHARGE, CHD7-spectrum, Branchiooculofacial, POMT1-spectrum, LEOPARD, and ADULT. Variants of uncertain significance (VUS) possibly associated to the phenotypes were found in six other individuals. Among the individuals with VUSes, three individuals presented variants in genes associated to defects of cilia structure and/or function, including DYNC2H1, KIAA0586, WDR34, INTU, RPGRIP1L, KIF7, and LMNA. These results show that WES was the most effective molecular approach for OC-MAC in this cohort. This study also reinforces the genetic heterogeneity of OC-MAC, and the importance of genes related to ciliopathies in this phenotype.

The presence and distribution of various genes in postnatal CLP-affected palatine tissue

BACKGROUND

Worldwide cleft lip with or without a cleft palate (CL/P) is the most common craniofacial birth defect. Apart from changes in facial appearance, additionally affected individuals often suffer from various associated comorbidities requiring complex multidisciplinary treatment with overall high expenses. Understanding the complete pathogenetic mechanisms of CL/P might aid in developing new preventative strategies and therapeutic approaches, help with genetic counselling, and improve quality of life. Many genes have been associated with the development of orofacial clefts; however, the majority require further research. Based on the role of PAX7, PAX9, SHH, SOX3, WNT3A, and WNT9B in orofacial development, the intention was to use chromogenic in situ hybridization to detect the six genes in postnatal CLP-affected palatine tissue and compare their distribution within the tissue samples.

RESULTS

Statistically significant differences in the distribution of PAX7, PAX9, WNT3A, and WNT9B were observed. In total, 19 pairs of moderate to very strong positive correlations were noted.

CONCLUSIONS

Changes in the cleft-affected palatine epithelium primarily seem to be associated with the PAX7 gene; however, PAX9, WNT3A, WNT9B, and SOX3 role seems to be more limited. Whilst connective tissue changes seem to depend on PAX7 only, SHH seems to participate individually and indistinctly. Numerous positive correlations reflect the complicating interactions of the pathways and their components in the orofacial cleft morphopathogenesis.

Genetic polymorphisms in CYP2B6 may be associated with lung cancer risk in the Chinese Han population

BACKGROUND

Our study aimed to elucidate the association between single nucleotide polymorphisms (SNPs) in CYP2B6 gene and susceptibility to lung cancer (LC).

METHODS

Five SNPs in CYP2B6 were genotyped in Chinese Han population (507 cases and 505 controls) utilizing Agena MassARRAY. The relationship between these SNPs and LC susceptibility was assessed using odds ratios, 95% confidence intervals, and χ2 tests. Additionally, multifactor dimensionality reduction was employed to analyze SNP-SNP interactions. Bioinformatics methods were applied to investigate the function of these SNPs.

RESULTS

We found that rs2099361 was associated with an increased susceptibility to LC in the codominant model (OR = 1.31, p = 0.045). Stratification analysis revealed the allele G at rs4803418 and the allele T at rs4803420 of CYP2B6 (BMI >24 kg/m2) were significantly linked to decreased susceptibility of LC. Conversely, the allele C at rs12979270 (BMI >24 kg/m2) showed increased susceptibility to LC. Moreover, a robust redundant relationship between rs12979270 and rs4803420 was identified in the study. According to the VannoPortal database, we found that rs4803420, rs12979270 and rs2099361 may modulate the binding affinity of LMNB1, SP1 and HDAC2, respectively.

CONCLUSIONS

Our results suggest that SNPs in the CYP2B6 gene play crucial roles in LC susceptibility.

Promoter-Adjacent DNA Hypermethylation Can Downmodulate Gene Expression: TBX15 in the Muscle Lineage

TBX15, which encodes a differentiation-related transcription factor, displays promoter-adjacent DNA hypermethylation in myoblasts and skeletal muscle (psoas) that is absent from non-expressing cells in other lineages. By whole-genome bisulfite sequencing (WGBS) and enzymatic methyl-seq (EM-seq), these hypermethylated regions were found to border both sides of a constitutively unmethylated promoter. To understand the functionality of this DNA hypermethylation, we cloned the differentially methylated sequences (DMRs) in CpG-free reporter vectors and tested them for promoter or enhancer activity upon transient transfection. These cloned regions exhibited strong promoter activity and, when placed upstream of a weak promoter, strong enhancer activity specifically in myoblast host cells. In vitro CpG methylation targeted to the DMR sequences in the plasmids resulted in 86−100% loss of promoter or enhancer activity, depending on the insert sequence. These results as well as chromatin epigenetic and transcription profiles for this gene in various cell types support the hypothesis that DNA hypermethylation immediately upstream and downstream of the unmethylated promoter region suppresses enhancer/extended promoter activity, thereby downmodulating, but not silencing, expression in myoblasts and certain kinds of skeletal muscle. This promoter-border hypermethylation was not found in cell types with a silent TBX15 gene, and these cells, instead, exhibit repressive chromatin in and around the promoter. TBX18, TBX2, TBX3 and TBX1 display TBX15-like hypermethylated DMRs at their promoter borders and preferential expression in myoblasts. Therefore, promoter-adjacent DNA hypermethylation for downmodulating transcription to prevent overexpression may be used more frequently for transcription regulation than currently appreciated.

Identification of risk variants related to malignant tumors in children with birth defects by whole genome sequencing

Background

Children with birth defects (BD) are more likely to develop cancer and the increased risk of cancer persists into adulthood. Prior population-based assessments have demonstrated that even non-chromosomal BDs are associated with at least two-fold increase of cancer risk. Identification of variants that are associated with malignant tumor in BD patients without chromosomal anomalies may improve our understanding of the underlying molecular mechanisms and provide clues for early cancer detection in children with BD.

Methods

In this study, whole genome sequencing (WGS) data of blood-derived DNA for 1653 individuals without chromosomal anomalies were acquired from the Kids First Data Resource Center (DRC), including 541 BD probands with at least one type of malignant tumors, 767 BD probands without malignant tumor, and 345 healthy family members who are the parents or siblings of the probands. Recurrent variants exclusively seen in cancer patients were selected and mapped to their corresponding genomic regions. The targeted genes/non-coding RNAs were further reduced using random forest and forward feature selection (ffs) models.

Results

The filtered genes/non-coding RNAs, including variants in non-coding areas, showed enrichment in cancer-related pathways. To further support the validity of these variants, blood WGS data of additional 40 independent BD probands, including 25 patients with at least one type of cancers from unrelated projects, were acquired. The counts of variants of interest identified in the Kid First data showed clear deviation in the validation dataset between BD patients with cancer and without cancer. Furthermore, a deep learning model was built to assess the predictive abilities in the 40 patients using variants of interest identified in the Kids First cohort as feature vectors. The accuracies are ~ 75%, with the noteworthy observation that variants mapped to non-coding regions provided the highest accuracy (31 out of 40 patients were labeled correctly).

Conclusion

We present for the first time a panorama of genetic variants that are associated with cancers in non-chromosomal BD patients, implying that our approach may potentially serve for the early detection of malignant tumors in patients with BD.

Spatiotemporal MicroRNA-Gene Expression Network Related to Orofacial Clefts

Craniofacial structures change dynamically in morphology during development through the coordinated regulation of various cellular molecules. However, it remains unclear how these complex mechanisms are regulated in a spatiotemporal manner. Here we applied natural cubic splines to model gene and microRNA (miRNA) expression from embryonic day (E) 10.5 to E14.5 in the proximal and distal regions of the maxillary processes to identify spatiotemporal patterns of gene and miRNA expression, followed by constructing corresponding regulatory networks. Three major groups of differentially expressed genes (DEGs) were identified, including 3,927 temporal, 314 spatial, and 494 spatiotemporal DEGs. Unsupervised clustering further resolved these spatiotemporal DEGs into 8 clusters with distinct expression patterns. Interestingly, we found 2 clusters of differentially expressed miRNAs: 1 had 80 miRNAs monotonically decreasing and the other had 97 increasing across developmental stages. To evaluate the phenotypic relevance of these DEGs during craniofacial development, we integrated data from the CleftGeneDB database and constructed the regulatory networks of genes related to orofacial clefts. Our analysis revealed 2 hub miRNAs, mmu-miR-325-3p and mmu-miR-384-5p, that repressed cleft-related genes Adamts3, Runx2, Fgfr2, Acvr1, and Edn2, while their expression increased over time. On the contrary, 2 hub miRNAs, mmu-miR-218-5p and mmu-miR-338-5p, repressed cleft-related genes Pbx2, Ermp1, Snai1, Tbx2, and Bmi1, while their expression decreased over time. Our experiments indicated that these miRNA mimics significantly inhibited cell proliferation in mouse embryonic palatal mesenchymal (MEPM) cells and O9-1 cells through the regulation of genes associated with cleft palate and validated the role of our regulatory networks in orofacial clefts. To facilitate interactive exploration of these data, we developed a user-friendly web tool to visualize the gene and miRNA expression patterns across developmental stages, as well as the regulatory networks (https://fyan.shinyapps.io/facebase_shiny/). Taken together, our results provide a valuable resource that serves as a reference map for future research in craniofacial development.

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

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

Evaluation of genome-wide association signals for nonsyndromic cleft lip with or without cleft palate in a multiethnic Brazilian population

OBJECTIVE

To evaluate previous nonsyndromic cleft lip with or without cleft palate (NSCL±P) associated signals in 4p16.2, 8p11.23, 12q13.13, 12q13.2 and 17q21.32 in a multiethnic Brazilian cohort.

DESIGN

The single nucleotide polymorphisms (SNPs) rs34246903 in 4p16.2, rs13317 in 8p11.23 (FGFR1, fibroblast growth factor receptor 1), rs3741442 in 12q13.13, rs705704 in 12q13.2 and rs4968247 in 17q21.32 were genotyped with TaqMan allelic discrimination assays in a case-control sample including 801 NSCL±P patients [233 nonsyndromic cleft lip (NSCLO) and 568 nonsyndromic cleft lip and palate (NSCLP)] and 881 healthy controls. Multiple logistic regression analyses, considering sex and genomic ancestry as covariates, were conducted, and the p value was adjusted with Bonferroni multiple correction testing (p ≤ 0.01).

RESULTS

Although several associations were identified, those that resisted the multiple correction testing involved the alleles and genotypes of rs34246903 and rs13317. The NSCLO group had a lower frequency of the minor C allele of rs34246903 compared to controls, giving an odds ratio (OR) of 0.74 [95% confidence interval (CI): 0.59-0.93, p = 0.01]. The rs34246903 CC genotype (homozygous) and the recessive model revealed significant protective associations with NSCLO, yielding ORs of 0.50 (95% CI: 0.29-0.85, p = 0.005) and 0.55 (95% CI: 0.33-0.93, p = 0.01) respectively. The presence of C variant allele of rs13317 (OR: 0.81, 95% CI: 0.69-0.96, p = 0.01) as well the TC genotype (OR: 0.77, 95% CI: 0.62-0.94, p = 0.01) and the dominant model (OR: 0.77, 95% CI: 0.63-0.94, p = 0.009) showed significant associations with reduced risk of NSCL±P.

CONCLUSION

Our study is the first to support the association of rs34246903 (4p16.2) with NSCLO and rs13317 within FGFR1 with NSCL±P in the highly admixed Brazilian population. Further studies are needed to determine the functionality of those SNPs or to identify the causal markers in linkage disequilibrium with those susceptibility markers.

Influences of the COVID-19 pandemic and response strategies on residents’ psychological state: The survey from Hainan Island

Mental health is a major public health issue that affects social development. This study aims to explore the psychological state of residents of Hainan Island and its influencing factors during the COVID-19 pandemic and to provide a scientific basis for the formulation of psychological counseling measures to be used after the pandemic. We used the nonprobability snowball sampling method to conduct an online survey from February 21 to February 28, 2020, and collected a sample of 533 respondents. Using a binary logistic regression model and network analysis, the psychological state of residents and the main factors were analyzed during the concentrated outbreak of COVID-19 (from January 20 to February 16, 2020). The study found that during the pandemic, 92.7% of the respondents were in a poor state of mind, and 54.2% experienced severe psychological stress. The mental state is spatially expressed as a pattern of “high in the middle and low in the surroundings.” Second, within the four-week sample, the overall psychological tension showed an inverted U-shaped trend. Respondents feeling stressed were most common in the second week, when they accounted for 87.99% of the total. Third, individual characteristics such as gender, age, fixed expenditure, and family size significantly affect the mental state. Women, the elderly, residents with fixed expenditures, and residents with large families are at greater risk of psychological stress. Finally, external factors such as the distance between residents and the location of cases and the node degree of the pandemic transmission network have a significant impact on the psychological state. However, residents in the least developed areas of Hainan Island, which are far away from active cases and have a low node degree, are more prone to psychological pressure. The government needs to pay special attention to these groups when constructing a long-term mechanism of psychological crisis intervention and increase public health resource investment in underdeveloped areas.

Evaluating the Expression of Candidate Homeobox Genes and Their Role in Local-Site Inflammation in Mucosal Tissue Obtained from Children with Non-Syndromic Cleft Lip and Palate

Craniofacial development including palatogenesis is a complex process which requires an orchestrated and spatiotemporal expression of various genes and factors for proper embryogenesis and organogenesis. One such group of genes essential for craniofacial development is the homeobox genes, transcriptional factors that are commonly associated with congenital abnormalities. Amongst these genes, DLX4, HOXB3, and MSX2 have been recently shown to be involved in the etiology of non-syndromic cleft lip and palate. Hence, we investigated the gene and protein expression of these genes in normal and cleft affected mucosal tissue obtained from 22 children, along with analyzing their role in promoting local-site inflammation using NF-κB. Additionally, we investigated the role of PTX3, which plays a critical role in tissue remodeling and wound repair. We found a residual gene and protein expression of DLX4 in cleft mucosa, although no differences in gene expression levels of HOXB3 and MSX2 were noted. However, a significant increase in protein expression for these genes was noted in the cleft mucosa (p < 0.05), indicating increased cellular proliferation. This was coupled with a significant increase in NF-κB protein expression in cleft mucosa (p < 0.05), highlighting the role of these genes in promotion of pro-inflammatory environment. Finally, no differences in gene expression of PTX3 were noted.

Association of BMP4 rs17563 Polymorphism with Nonsyndromic Cleft Lip with or without Cleft Palate Risk: Literature Review and Comprehensive Meta-Analysis

Although published individual studies have reported associations between BMP4 rs17563 polymorphism and nonsyndromic cleft lip with or without cleft palate (NSCLP) risk, the results are conflicting. This meta-analysis was conducted to assess the association based on multiple studies. Methods: A comprehensive literature search up to October 1st, 2019 was performed using PubMed, Science Direct, China National Knowledge Infrastructure (CNKI), and Wanfang databases. Results: Fourteen case-control studies with 2,058 NSCLP cases and 2,557 controls were selected. There was no significant association between BMP4 rs17563 polymorphism and risk of NSCLP overall. Subgroup analysis revealed that BMP4 rs17563 polymorphism was associated with NSCLP risk in Chinese and Brazilian populations. Conclusions: This meta-analysis suggests that BMP4 rs17563 polymorphism was not associated with NSCLP risk in overall population. However, BMP4 rs17563 polymorphism may be a risk factor for development of NSCLP in Chinese and Brazilians.

Family based and case-control designs reveal an association of TFAP2A in nonsyndromic cleft lip only among Vietnamese population

Aims

Dozens of causative genes and their mechanisms of nonsyndromic cleft lip with or without cleft palate (NSCL/P) were revealed through genome‐wide association and linkage studies. Results were, however, not always replicated in different populations or methodologies. This study used case–control and family based approaches to investigate the etiology of NSCL/P and its two subtypes: nonsyndromic cleft lip only (NSCLO) and nonsyndromic cleft lip and palate (NSCLP) among the Vietnamese population.

Methods

Two hundred and seventeen NSCL/P case‐parent trios (one affected child and two parents), including 105 NSCLO and 112 NSCLP were involved for a family based design; and 273 ethnic and region‐matched healthy controls with no cleft history in their families were recruited for a case–control design. Three SNPs consisting of TFAP2A (rs1675414 and rs303048) and 8q24 (rs987525) were genotyped using the TaqMan SNP genotyping assay.

Results

TFAP2A rs1675414 was associated with NSCLO, replicated by both case‐control and family based tests. Other SNPs yielded no evidence of susceptibility to NSCL/P or two subtypes.

Conclusion

The current investigation suggests an intriguing role of TFAP2A in the etiology of NSCLO among the Vietnamese population.

This study used case‐control and family‐based approaches to investigate the etiology of NSCL/P and its two subtypes: nonsyndromic cleft lip only (NSCLO), nonsyndromic cleft lip and palate (NSCLP) among Vietnamese population. TFAP2A rs1675414 was associated with NSCLO, replicated by both case‐control and family‐based tests.

Mitochondrial ATP-Dependent Proteases-Biological Function and Potential Anti-Cancer Targets

Cells must eliminate excess or damaged proteins to maintain protein homeostasis. To ensure protein homeostasis in the cytoplasm, cells rely on the ubiquitin-proteasome system and autophagy. In the mitochondria, protein homeostasis is regulated by mitochondria proteases, including four core ATP-dependent proteases, m-AAA, i-AAA, LonP, and ClpXP, located in the mitochondrial membrane and matrix. This review will discuss the function of mitochondrial proteases, with a focus on ClpXP as a novel therapeutic target for the treatment of malignancy. ClpXP maintains the integrity of the mitochondrial respiratory chain and regulates metabolism by degrading damaged and misfolded mitochondrial proteins. Inhibiting ClpXP genetically or chemically impairs oxidative phosphorylation and is toxic to malignant cells with high ClpXP expression. Likewise, hyperactivating the protease leads to increased degradation of ClpXP substrates and kills cancer cells. Thus, targeting ClpXP through inhibition or hyperactivation may be novel approaches for patients with malignancy.

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.

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.

Brazil's Craniofacial Project: Different approaches on orofacial clefts and 22q11.2 deletion syndrome

This article reports the present situation of Brazilian health care in genetics for Orofacial Cleft (OFC) and 22q11.2 Deletions Syndrome (22q11.2 DS) based on research conducted by Brazil's Craniofacial Project (BCFP). Established in 2003, BCFP is a voluntary and cooperative network aiming to investigate the health care of people with these diseases and other craniofacial anomalies. The initiatives and research results are presented in four sections: (a) a comprehensive report of the Brazilian public health system in craniofacial genetics; (b) multicentric studies developed on OFC and 22q11.2 DS; (c) education strategies focused on addressing these conditions for both population and health-care professionals; and (d) the nosology through the Brazilian Database on Craniofacial Anomalies (BDCA). Since 2006, BDCA uses a standardized method with detailed clinical data collection, which allows for conducting studies on nosology, genotype-phenotype correlations, and natural history; data can also contribute to public policies. Currently, the BDCA stores data on 1,724 individuals, including 1,351 (78.36%) who were primarily admitted due to OFC and 373 (21.63%) with clinical suspicion of 22q11.2 DS. Chromosomal abnormalities/genomic imbalances were represented by 92/213 (43.19%) individuals with syndromic OFC, including 43 with 22q11.2 DS, which indicates the need for chromosomal microarray analysis in this group. The nosologic diversity reinforces that monitoring clinical is the best strategy for etiological investigation. BCFP's methodology has introduced the possibility of increasing scientific knowledge and genetic diagnosis of OFC and 22q11.2 DS to in turn improve health care and policies for this group of diseases.

Genetics and signaling mechanisms of orofacial clefts

Craniofacial development involves several complex tissue movements including several fusion processes to form the frontonasal and maxillary structures, including the upper lip and palate. Each of these movements are controlled by many different factors that are tightly regulated by several integral morphogenetic signaling pathways. Subject to both genetic and environmental influences, interruption at nearly any stage can disrupt lip, nasal, or palate fusion and result in a cleft. Here, we discuss many of the genetic risk factors that may contribute to the presentation of orofacial clefts in patients, and several of the key signaling pathways and underlying cellular mechanisms that control lip and palate formation, as identified primarily through investigating equivalent processes in animal models, are examined.

[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.

Machine learning in prediction of genetic risk of nonsyndromic oral clefts in the Brazilian population

OBJECTIVES

Genetic variants in multiple genes and loci have been associated with the risk of nonsyndromic cleft lip with or without cleft palate (NSCL ± P). However, the estimation of risk remains challenge, because most of these variants are population-specific rendering the identification of the underlying genetic risk difficult. Herein we examined the use of machine learning network in previously reported single nucleotide polymorphisms (SNPs) to predict risk of NSCL ± P in the Brazilian population.

MATERIALS AND METHODS

Random forest and neural network methods were applied in 72 SNPs in a case-control sample composed by 722 NSCL ± P and 866 controls for discrimination of NSCL ± P risk. SNP-SNP interactions and functional annotation biological processes associated with the identified NSCL ± P risk genes were verified.

RESULTS

Supervised random forest decision trees revealed high scores of importance for the SNPs rs11717284 and rs1875735 in FGF12, rs41268753 in GRHL3, rs2236225 in MTHFD1, rs2274976 in MTHFR, rs2235371 and rs642961 in IRF6, rs17085106 in RHPN2, rs28372960 in TCOF1, rs7078160 in VAX1, rs10762573 and rs2131960 in VCL, and rs227731 in 17q22, with an accuracy of 99% and an error rate of approximately 3% to predict the risk of NSCL ± P. Those same 13 SNPs were considered the most important for the neural network to effectively predict NSCL ± P risk, with an overall accuracy of 94%. Multivariate regression model revealed significant interactions among all SNPs, with an exception of those in FGF12 and MTHFD1. The most significantly biological processes for selected genes were those involved in tissue and epithelium development; neural tube closure; and metabolism of methionine, folate, and homocysteine.

CONCLUSIONS

Our results provide novel clues for genetic mechanism studies of NSCL ± P and point out for a machine learning model composed by 13 SNPs that is capable of predicting NSCL ± P risk.

CLINICAL RELEVANCE

Although validation is necessary, this genetic panel can be useful in the near future to assist in NSCL ± P genetic counseling.

Association between MSX1 rs12532 polymorphism with nonsyndromic unilateral complete cleft lip and palate and tooth agenesis

OBJECTIVES

To investigate the association of MSX1 rs12532 polymorphism with the risk of nonsyndromic unilateral complete cleft lip and palate (NSCLP) and tooth agenesis.

MATERIALS AND METHODS

The study is comprised of 384 individuals divided into 4 groups: group 1, patients with unilateral complete NSCLP and premolar agenesis (n = 57); group 2, patients with unilateral NSCLP without tooth agenesis (n = 117); group 3, patients with premolar agenesis without oral cleft (n = 53) and group 4 (n = 157), a control group with individuals without tooth agenesis and oral cleft. Genotyping of rs12532 was carried out with Taqman chemistry, and associations were investigated using logistic regression analyses.

RESULTS

Overall rs12532 allele and genotype distributions revealed no significant differences between the groups of NSCLP or tooth agenesis.

CONCLUSION

Although our results are consistent with a lack of association of MSX1 rs12532 and the risk of unilateral NSCLP and tooth agenesis, further studies with additional SNPs and a more diverse ethnic cohort are warranted.

miRNAs as biomarkers of orofacial clefts: A systematic review

Orofacial clefts are facial malformations caused by the improper development of the lips and palate. Many genetic and epigenetic molecules have been involved in the mechanisms of orofacial clefts, one of which are miRNAs. This systematic review aimed to identify miRNAs associated to non-syndromic orofacial clefts in humans. After applying a series of criteria, four studies were selected for analysis. In total, one hundred miRNAs were observed in the literature, of which 57 were reported as upregulated and 43 as downregulated in all orofacial cleft classifications. Moreover, nine miRNAs were differentially expressed only in cleft palate patients, which might suggest distinct regulatory mechanisms for the etiology of cleft lips and palates. We suggest broader population sampling in order to include diverse ethnic groups in the future, as well as analyses toward identifying miRNA target genes and pathways. We highlight the need for experimental validation and of these results to allow further translational approaches and clinical applications.

Genomic analyses in African populations identify novel risk loci for cleft palate

Orofacial clefts are common developmental disorders that pose significant clinical, economical and psychological problems. We conducted genome-wide association analyses for cleft palate only (CPO) and cleft lip with or without palate (CL/P) with ~17 million markers in sub-Saharan Africans. After replication and combined analyses, we identified novel loci for CPO at or near genome-wide significance on chromosomes 2 (near CTNNA2) and 19 (near SULT2A1). In situ hybridization of Sult2a1 in mice showed expression of SULT2A1 in mesenchymal cells in palate, palatal rugae and palatal epithelium in the fused palate. The previously reported 8q24 was the most significant locus for CL/P in our study, and we replicated several previously reported loci including PAX7 and VAX1.

Non-syndromic Cleft Lip and Palate Polymorphisms Affect Normal Lip Morphology

Non-syndromic cleft lip with or without palate (NSCL/P) is a frequent malformation of the facial region. Genetic variants (SNPs) within nineteen loci have been previously associated with NSCL/P in GWAS studies of European individuals. These common variant SNPs may have subtler effects on the morphology of the lip and face in unaffected individuals. Several studies have investigated the genetic influences on facial morphology using land-marking methods, but these landmarks are sparse in the lip region. The aim of this study is to assess for associations between the nineteen NSCL/P SNPs and normal lip phenotypes, using a detailed categorical scale. Three-dimensional laser scanned facial images were obtained of 4,747 subjects recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC) and genetic data was available for 3,643 of them. A polygenetic risk score (PRS) combining the nineteen NSCL/P SNPs was associated with V-shaped Cupid's bow (P = 3 × 10-4) and narrow philtrum (P = 2 × 10-4) phenotypes. Analysis of individual SNPs found strong evidence for association between rs227731 and skeletal II pattern (P = 5 × 10-6). This study finds that known NSCL/P SNPs affect lip phenotypes in the general population, and an increased PRS is associated with narrow philtrum and V-shaped Cupid's bow. However, the difference in NSCL/P PRS between people with and without certain lip features is unlikely to be great enough to serve as a useful marker of NSCL/P risk.

Gene-Gene Interactions among SPRYs for Nonsyndromic Cleft Lip/Palate

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect with a complex genetic architecture. Gene-gene interactions have been increasingly regarded as contributing to the etiology of NSCL/P. A recent genome-wide association study revealed that a novel single-nucleotide polymorphism at SPRY1 in 4q28.1 showed a significant association with NSCL/P. In the current study, we explored the role of 3 SPRY genes in the etiology of NSCL/P by detecting gene-gene interactions: SPRY1, SPRY2, and SPRY4-with SPRY3 excluded due to its special location on the X chromosome. We selected markers in 3 SPRY genes to test for gene-gene interactions using 1,908 case-parent trios recruited from an international consortium established for a genome-wide association study of nonsyndromic oral clefts. As the trios came from populations with different ancestries, subgroup analyses were conducted among Europeans and Asians. Cordell's method based on conditional logistic regression models was applied to test for potential gene-gene interactions via the statistical package TRIO in R software. Gene-gene interaction analyses yielded 10 pairs of SNPs in Europeans and 6 pairs in Asians that achieved significance after Bonferroni correction. The significant interactions were confirmed in the 10,000-permutation tests (empirical P = 0.003 for the most significant interaction). The study identified gene-gene interactions among SPRY genes among 1,908 NSCL/P trios, which revealed the importance of potential gene-gene interactions for understanding the genetic architecture of NSCL/P. The evidence of gene-gene interactions in this study also provided clues for future biological studies to further investigate the mechanism of how SPRY genes participate in the development of NSCL/P.

TGFα/HinfI Polymorphisms Contribute to Nonsyndromic Cleft Lip and Palate in Turkish Patients

BACKGROUND

Nonsyndromic cleft lip with/without cleft palate (nsCL ± P) is one of the most common birth defects of complex etiology, occurring in ∼1/700 live births worldwide. A series of epidemiological studies were conducted to investigate the association between a transforming growth factor alpha (TGFα) polymorphism and nsCL ± P risk. The aim of this study was to investigate the association between the TGFα/HinfI polymorphisms and nsCL ± P in Turkish patients.

METHODS

One hundred fifty-five Turkish subjects were enrolled: 70 nsCL ± P patients and 85 unrelated control individuals. Genomic DNA was isolated from peripheral blood leukocytes, and molecular analysis of gene polymorphisms was carried out using polymerase chain reaction and restriction enzyme digestions.

RESULTS

We found significant difference between the TGFα gene HinfI allele frequencies of the controls and: 1) the occurrence of nonsyndromic cleft lip (p = 0.029,); 2) the occurrence of nonsyndromic cleft lip and palate (nsCL + P) cases (p = 0.024; and 3) the occurrence of both nsCL ± nsCLP cases (p = 0.0365). The association between age of parents, gender, maternal exposures, socioeconomic status and clefts was assessed in each group separately.

CONCLUSION

Our study indicates that the TGFα HinfI gene polymorphism might be associated with nsCL ± P susceptibility, thus contributing to the occurrence of nsCL ± P in Turkish patients. The relatively small sample size of our study is one limitation of our study, and future research with larger specimen sets from different ethnicities will be required to validate our findings.

Single SNP- and pathway-based genome-wide association studies for beak deformity in chickens using high-density 600K SNP arrays

Background

Beak deformity, typically expressed as the crossing of upper and lower mandibles, is found in several indigenous chicken breeds, including the Beijing-You chickens studied here. Beak deformity severely impairs the birds’ growth and welfare. Although previous studies shed some light on the genetic regulation of this complex trait, the genetic basis of this malformation remains incompletely understood.

Results

In this study, single SNP- and pathway-based genome-wide association studies (GWASs) were performed using ROADTRIPS and SNP ratio test (SRT), respectively. A total of 48 birds with deformed beaks (case) and 48 normal birds (control) were genotyped using Affymetrix 600 K HD genotyping arrays. As a result, 95 individuals and 429,539 SNPs were obtained after quality control. The P-value was corrected by a Bonferroni adjustment based on linkage disequilibrium pruning. The single SNP-based association study identified one associated SNP with 5% genome-wide significance and seven suggestively associated SNPs. Four high-confidence genes, LOC421892, TDRD3, RET, and STMN1, were identified as the most promising candidate genes underlying this complex trait in view of their positions, functions, and overlaps with previous studies. The pathway-based association study highlighted the association of six pathways with beak deformity, including the calcium signaling pathway.

Conclusions

Potentially useful candidate genes and pathways for beak deformity were identified, which should be the subject of further functional characterization.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4882-8) contains supplementary material, which is available to authorized users.

Association of WNT Pathway Genes With Nonsyndromic Cleft Lip With or Without Cleft Palate

OBJECTIVE

Nonsyndromic cleft lip with or without cleft palate (NSCL±P) is a common craniofacial anomaly with multifactorial etiology. Evidence suggests that variations in WNT pathway genes contribute to an increased susceptibility to NSCL±P. The aim of this study was to investigate the association of AXIN1, APC, CTNNB1, DVL2, and GSK3β gene variants with NSCL±P in a case-control data set from Brazil.

PATIENTS

471 individuals with NSCL±P and 504 unrelated control individuals of Caucasian ethnicity.

DESIGN

Twenty single-nucleotide polymorphisms (SNPs) in/nearby AXIN1, APC, CTNNB1, DVL2, and GSK3B genes were genotyped using Taqman chemistry in a Viia7 sequence detection instrument. Genotype, allele, and haplotype frequencies were compared among NSCL±P patients and controls using Fisher exact test, implemented in PLINK software. The level of significance was established at P ≤.002 under Bonferroni correction. In silico analysis of SNP function was assessed using MirSNP database.

RESULTS

Significant association was found between GSK3B rs13314595 genotypes and NSCL±P ( P = .0006). Additionally, nominal associations were found between DVL2 (rs35594616) and APC (rs448475) with NSCL±P ( P = .02 and P = .03, respectively). SNP haplotypes for GSK3B and APC genes showed nominal associations with NSCL±P ( P < .05). In silico analysis predicted that APC rs448475 harbors a binding site for the microRNA miR-617 and that the switch from a G allele to C allele enhances binding, whereas DVL2 rs35594616 did not appear to harbor microRNA-binding sites.

CONCLUSION

This study shows for the first time the association between GSK3B and NSCL±P and confirms the role of additional WNT pathway genes as candidates for NSCL±P.

Association of single nucleotide polymorphisms in AXIN2, BMP4, and IRF6 with Non-Syndromic Cleft Lip with or without Cleft Palate in a sample of the southeast Iranian population

OBJECTIVES

Non-syndromic cleft lip with or without palate (NSCL/P) is a common congenital malformation worldwide, with complex etiology. It has been proposed that interaction of genes and environmental factors play a role in the predisposition to this disease. The aim of this study was to examine the association between AXIN2 (axis inhibition protein 2) rs7224837, BMP4 (bone morphogenetic protein 4) rs17563, and IRF6 (interferon regulatory factor 6) rs861019 and 2235371 polymorphisms and NSCL/P in an Iranian population.

MATERIAL AND METHODS

This case-control study was carried out on 132 unrelated NSCL/P patients and 156 healthy subjects. The variants were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The findings suggest that BMP4 rs17563 polymorphism significantly decreased the risk of NSCL/P in codominant (OR=0.36, 95%CI=0.17-0.79, p=0.012, CT vs CC and OR=0.11, 95%CI=0.01-0.88, p = 0.019, TT vs CC), dominant (OR=0.30, 95%CI=0.15-0.62, p = 0.0007, CT+TT vs CC), recessive (OR=0.12, 95%CI=0.02-0.99, p = 0.023, TT vs CC+CT), overdominant (OR=0.39, 95%CI = 0.18-0.84, p=0.021, CT vs CC+TT), and allele (OR=0.28, 95%CI=0.15-0.55, p<0.0001, T vs C) inheritance models. Our findings did not support an association between AXIN2 rs7224837 and IRF6 rs861019 polymorphism and risk/protection of NSCL/P. The IRF6 2235371 variant was not polymorphic in our population.

CONCLUSION

The results indicate that the BMP4 rs17563 variant is likely to confer a protective effect against the occurrence of NSCL/P in a sample of the southeast Iranian population.

The developmental biology of genetic Notch disorders

Notch signaling regulates a vast array of crucial developmental processes. It is therefore not surprising that mutations in genes encoding Notch receptors or ligands lead to a variety of congenital disorders in humans. For example, loss of function of Notch results in Adams-Oliver syndrome, Alagille syndrome, spondylocostal dysostosis and congenital heart disorders, while Notch gain of function results in Hajdu-Cheney syndrome, serpentine fibula polycystic kidney syndrome, infantile myofibromatosis and lateral meningocele syndrome. Furthermore, structure-abrogating mutations in NOTCH3 result in CADASIL. Here, we discuss these human congenital disorders in the context of known roles for Notch signaling during development. Drawing on recent analyses by the exome aggregation consortium (EXAC) and on recent studies of Notch signaling in model organisms, we further highlight additional Notch receptors or ligands that are likely to be involved in human genetic diseases.

Vax1 Plays an Indirect Role in the Etiology of Murine Cleft Palate

Cleft lip with or without palate (CLP) and isolated cleft palate (CP) are common human developmental malformations with a complex etiology that reflects a failure of normal facial development. VAX1 encodes a homeobox-containing transcription factor identified as a candidate gene for CLP in human populations, with targeted deletion in mice associated with multiple anomalies, including disruption of the visual apparatus and basal forebrain, lobar holoprosencephaly, and CP. We have investigated Vax1 function during murine palatogenesis but found no evidence for a direct role in this process. Vax1 is not expressed in the developing palate and mutant palatal shelves elevate above the tongue, demonstrating morphology and proliferation indices indistinguishable from wild type. However, mutant mice did have a large midline cavity originating from the embryonic forebrain situated beneath the floor of the hypothalamus and extending through the nasal cavity to expand this region and prevent approximation of the palatal shelves. Interestingly, despite strong expression of Vax1 in ectoderm of the medial nasal processes, the upper lip remained intact in mutant mice. We found further evidence of disrupted craniofacial morphology in Vax1 mutants, including truncation of the midface associated with reduced cell proliferation in forebrain neuroectoderm and frontonasal mesenchyme. Sonic hedgehog (Shh) signal transduction was downregulated in the mutant forebrain, consistent with a role for Vax1 in mediating transduction of this pathway. However, Shh was also reduced in this region, suggestive of a Shh-Vax1 feedback loop during early development of the forebrain and a likely mechanism for the underlying lobar holoprosencephaly. Despite significant associations between VAX1 and human forms of CLP, we find no evidence of a direct role for this transcription factor in development of this region in a mutant mouse model.

BMP4 rs17563 polymorphism and nonsyndromic cleft lip with or without cleft palate: A meta-analysis

BACKGROUND

Previous studies have investigated the relationship between human bone morphogenetic protein 4 gene (BMP4) rs17563 polymorphism and nonsyndromic cleft lip with or without cleft palate (NSCL/P). However, the results remained inconsistent. Therefore, we conducted a meta-analysis to assess the effect of BMP4 rs17563 polymorphism on NSCL/P.

METHODS

Electronic searches in 5 databases were conducted to select all eligible studies up to March 2017. Odds ratios (ORs) with the corresponding 95% confidence intervals (CIs) were calculated to estimate the association. Sensitivity analysis was performed to evaluate the results stability by excluding each study in turn. Publication bias was assessed by Begg funnel plots and Egger test.

RESULTS

A total of 11 case-control studies were included in the meta-analysis. The pooled frequency of the minor allele C for BMP4 rs17563 was lower in Asians (pooled frequency = 0.33, 95% CI: 0.29-0.37) than in Brazilian population (pooled frequency = 0.47, 95% CI: 0.40-0.54). The overall results showed no significant association of BMP4 rs17563 polymorphism with NSCL/P risk. However, the results turned out to be different when stratified by ethnicity. BMP4 rs17563 polymorphism was associated with a higher risk of NSCL/P among Asian ethnicity (C vs T: OR = 1.33, 95% CI: 1.02-1.73; CC vs TT: OR = 2.10, 95% CI: 1.28-3.43; CC vs TT + TC: OR = 2.16, 95% CI: 1.34-3.47) and among Caucasian population (TC vs TT: OR = 3.36, 95% CI: 2.03-5.54; TC + CC vs TT: OR = 3.71, 95% CI: 2.43-5.69). Among Brazilian population, BMP4 rs17563 polymorphism exerted a significantly protective effect on NSCL/P (C vs T: OR = 0.70, 95% CI: 0.58-0.84; CC vs TT: OR = 0.54, 95% CI: 0.33-0.88; TC vs TT: OR = 0.55, 95% CI: 0.44-0.69; TC + CC vs TT: OR = 0.56, 95% CI: 0.45-0.69).

CONCLUSION

The results suggest that the C allele of BMP4 rs17563 may be a risk factor for NSCL/P among Asians and Caucasians, and may be a protective factor for NSCL/P in Brazilian population. Future large-sample studies with appropriate designs among specific populations are warranted to evaluate the association.

Inducible Nitric Oxide Synthase Polymorphisms and Nitric Oxide Levels in Individuals with Chronic Periodontitis

This study aimed to investigate whether the -1026(A>C)(rs2779249) and +2087(A>G)(2297518) polymorphisms in the NOS2 gene were associated with chronic periodontitis (CP) and with salivary levels of nitrite (NO₂^-) and/or nitrate + nitrite (NOx). A group of 113 mixed-race patients were subjected to periodontal, genetic, and biochemical evaluations (65 CP/48 periodontally healthy subjects). DNA was extracted from oral epithelial cells and used for genotyping by polymerase chain reaction (real-time). Salivary NOx concentrations were determined using an ozone-based chemiluminescence assay. Association of CP with alleles and genotypes of the -1026(A>C) polymorphism was found (X² test, p = 0.0075; 0.0308), but this was not maintained after multiple logistic regression, performed to estimate the effect of covariates and polymorphisms in CP. This analysis demonstrated, after correction for multiple comparisons, that only the female gender was significantly associated with CP. Polymorphisms analyzed as haplotypes were not associated with CP. NOx levels were significantly higher in the control group of heterozygous individuals for both polymorphisms. In conclusion, the female gender was significantly associated with CP, and higher levels of salivary NOx were found in control subjects and associated with the heterozygous state of the NOS2 polymorphisms, reinforcing the potential of NO metabolites as markers of periodontitis status.

The recurrence risk of genetic complex diseases

Complex inherited diseases affected by an interaction between collective effects of the genotype at one or multiple loci either to increase or to lower susceptibility to disease, combined with a variety of environmental exposures that may trigger, accelerate, exacerbate, or protect against the disease process. The new aspects of genetic techniques have been opened for diagnosis and analysis of inherited disorders. While appropriate Mendelian laws is applied to estimate the recurrence risk of single gene diseases, using empirical recurrence risks are the most important and available method to evaluate pedigree of complex (multifactorial), chromosomal, and unknown etiology disorders. Although, generally, empirical recurrent risks are not accurate, either because of the difference of gene frequencies and environmental factors among populations or heterogeneity of disease; using results of plenty family population studies, computerized estimating programs, genotyping technologies, and Genome-wide association studies (GWASs) of single nucleotide polymorphisms (SNPs), can make it possible nowadays to estimate these risks. The specific family situation and importance recurrence risks of some common complex genetic diseases will be presented in this review and some important multifactorial disorders’ recurrence risks will be summarized to help genetic counselors for supporting families and representing better view of genetic disorders.

Association Studies and Direct DNA Sequencing Implicate Genetic Susceptibility Loci in the Etiology of Nonsyndromic Orofacial Clefts in Sub-Saharan African Populations

Orofacial clefts (OFCs) are congenital dysmorphologies of the human face and oral cavity, with a global incidence of 1 per 700 live births. These anomalies exhibit a multifactorial pattern of inheritance, with genetic and environmental factors both playing crucial roles. Many loci have been implicated in the etiology of nonsyndromic cleft lip with or without cleft palate (NSCL/P) in populations of Asian and European ancestries, through genome-wide association studies and candidate gene studies. However, few populations of African descent have been studied to date. Here, the authors show evidence of an association of some loci with NSCL/P and nonsyndromic cleft palate only (NSCPO) in cohorts from Africa (Ghana, Ethiopia, and Nigeria). The authors genotyped 48 single-nucleotide polymorphisms that were selected from previous genome-wide association studies and candidate gene studies. These markers were successfully genotyped on 701 NSCL/P and 163 NSCPO cases, 1,070 unaffected relatives, and 1,078 unrelated controls. The authors also directly sequenced 7 genes in 184 nonsyndromic OFC (NSOFC) cases and 96 controls from Ghana. Population-specific associations were observed in the case-control analyses of the subpopulations, with West African subpopulations (Ghana and Nigeria) showing a similar pattern of associations. In meta-analyses of the case-control cohort, PAX7 (rs742071, P = 5.10 × 10(-3)), 8q24 (rs987525, P = 1.22 × 10(-3)), and VAX1 (rs7078160, P = 0.04) were nominally associated with NSCL/P, and MSX1 (rs115200552, P = 0.01), TULP4 (rs651333, P = 0.04), CRISPLD2 (rs4783099, P = 0.02), and NOG1 (rs17760296, P = 0.04) were nominally associated with NSCPO. Moreover, 7 loci exhibited evidence of threshold overtransmission in NSOFC cases through the transmission disequilibrium test and through analyses of the family-based association for disease traits. Through DNA sequencing, the authors also identified 2 novel, rare, potentially pathogenic variants (p.Asn323Asp and p.Lys426IlefsTer6) in ARHGAP29 In conclusion, the authors have shown evidence for the association of many loci with NSCL/P and NSCPO. To the best of this knowledge, this study is the first to demonstrate any of these association signals in any African population.