Bilateral Cleft Lip Repair: Lessons from History

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the bilateral cleft lip and nasal deformity and associated anatomical variations. 2. Understand the history and evolution of the bilateral cleft lip repair. 3. Understand the key principles of the surgical repair.

SUMMARY

This article describes characteristics of the bilateral cleft lip and nasal deformity and its management, including presurgical orthopedics, operative techniques, and postsurgical care.

Association of Fetal MTHFR 677C > T Polymorphism with Non-Syndromic Cleft Lip with or without Palate Risk: A Systematic Review and Meta-Analysis

This study was conducted to estimate the precise association of fetal MTHFR 677 C > T polymorphism with risk of nonsyndromic cleft lip with or without cleft palate (NSCL ± P) using a large-scale meta-analysis. Methods: A comprehensive literature search was performed using studies published on PubMed, Science Direct, Scopus and CNKI databases up to November 1, 2019. Results: A total of 38 studies with 6,525 children with NSCL ± P and 8,606 controls were selected. Overall, there was a significant association between MTHFR 677 C > T polymorphism and NSCL ± P risk. Subgroup analysis by ethnicity revealed that MTHFR 677 C > T polymorphism contributed to development of NSCL ± P in Caucasian and Mixed populations, but not in Asians. When stratified by country of origin, we found a significant association in Brazilian, Turkish and Indian populations, but not in Chinese and US-American. Conclusions: This meta-analysis provides strong evidence that fetal MTHFR 677 C > T polymorphism is significantly associated with NSCL ± P risk.

Update in Unilateral Cleft Lip Surgery

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Describe the unilateral cleft lip and nasal deformity and associated anatomical variations. 2. Understand the history and evolution of the unilateral cleft lip repair. 3. List different presurgical treatment options. 4. Differentiate between surgical techniques.

SUMMARY

This article describes characteristics of the unilateral cleft lip and nasal deformity and its management, including presurgical orthopedics, operative techniques, and postsurgical care. The rotation-advancement and straight-line repairs are discussed in detail, as are the current concepts in primary cleft nose repair.

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.

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.

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.

Methylenetetrahydrofolate reductase C677T polymorphism is not associated with the risk of nonsyndromic cleft lip/palate: An updated meta-analysis

Both genetic and environmental factors affect the risk of orofacial clefts. The present meta-analysis aimed to evaluate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and risk of nonsyndromic cleft lip/palate (NSCL/P) in cases-control studies. The PubMed/Medline, Scopus, Web of Science, and Cochrane Library databases were searched up to April 2019 with no restrictions. The odds ratios (ORs) and 95% confidence intervals (CIs) in all analyses were calculated by Review Manager 5.3 software. The funnel plot analysis was carried out by the Comprehensive Meta-Analysis version 2.0 software. Subgroup analysis, meta-regression, and sensitivity analysis were performed for the pooled analyses. Thirty-one studies reviewed in this meta-analysis included 4710 NSCL/P patients and 7271 controls. There was no significant association between MTHFR C677T polymorphism and NSCL/P susceptibility related to allelic model (OR = 1.04; P = 0.49), homozygote model (OR = 1.11; P = 0.35), heterozygote model (OR = 0.99; P = 0.91), dominant model (OR = 1.00; P = 0.96), or recessive model (OR = 1.08; P = 0.23). There was no significant association between MTHFR C677T polymorphism and NSCL/P susceptibility based on the ethnicity or the source of cases. There was a significant linear relationship between the year of publication and log ORs for the allele model. The results of the present meta-analysis failed to show an association between MTHFR C677T polymorphism and NSCL/P susceptibility. The subgroup analyses based on the ethnicity and the source of cases further confirmed this result.

Assessment of candidate genes and genetic heterogeneity in human non syndromic orofacial clefts specifically non syndromic cleft lip with or without palate

Non syndromic orofacial clefts specifically non-syndromic cleft lip/palate are one of the most common craniofacial malformation among birth defects in human having multifactorial etiology with an incidence of 1:700/1000. On the basis of association with other congenital malformations or their presence as isolated anomaly, OFC can be classified as syndromic (30%) and nonsyndromic (70%) respectively. The major cause of disease demonstrates complex interplay between genetic and environmental factors. The pathogenic mechanism of underlying factors have been provided by different genetic studies on large-scale with significant recent advances in genotyping technologies usually based on linkage or genome wide association studies (GWAS). On the basis of recent studies, new tools to identify causative genes involved in NSCL/P reported approximately more than 30 genetic risk loci that are responsible for pathogenesis of facial deformation. Despite these findings, it is still uncertain that how much of variance in NSCL/P predisposing factors can be explain by identified risk loci, as they all together accounts for only 20%-25% of NSCL/P heritability. So there is need of further findings about the problem of rare low frequency coding variants and other missing responsive factors or genetic modifiers. This review will described those potential genes and loci reported in different studies whose involvement in pathogenesis of nonsyndromic OFC has wide scientific evidence.

Association between methylenetetrahydrofolate reductase polymorphisms and non-syndromic cleft lip with or without palate susceptibility: an updated systematic review and meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms are thought to be involved in the development of cleft lip with or without cleft palate (NSCL/P), but published results are contradictory. We therefore designed an updated meta-analysis to pool eligible studies and to evaluate further the possible relations between MTHFR polymorphisms (c.677C>T and c.1298A>C) and susceptibility to NSCL/P. A comprehensive search based on PubMed, Medline, Web of Science, and Embase databases was made up to February 2018. Twenty-three case-control and 10 case-parent trio studies (including 1149 cases and 1161 controls) were retrieved. Odds ratio (OR) with 95% CI were used to estimate the pooled strength of association under different genetic models. The Q test and I² test were used to estimate heterogeneity among studies, the quality of which was assessed using the Newcastle-Ottawa scale. In the MTHFR c.677C>T polymorphism group, there were significant overall results for the recessive (OR 1.231, 95%CI 1.092 to 1.387) and homozygote (OR 1.252, 95%CI 1.078 to 1.456) models. Subgroup analysis by subjects and ethnicity identified only associations in European mothers for the recessive model and the homozygote model. For the c.1298A>C group, there were no significant results for either European or Asian patients for all genetic models. The MTHFR c.677C>T polymorphism might increase susceptibility to NSCL/P in European mothers, but was negatively associated in Asian patients, and the MTHFR c.1298A>C polymorphism is not involved in the development of NSCL/P in either European or Asian patients.

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.

MTR, MTRR, and MTHFR Gene Polymorphisms and Susceptibility to Nonsyndromic Cleft Lip With or Without Cleft Palate

OBJECTIVE

To examine the associations of methionine synthase (MTR), methionine synthase reductase (MTRR), and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms with the susceptibility to nonsyndromic cleft lip with or without cleft palate (NSCL/P).

METHODS

Between May 2012 and August 2014, 147 NSCL/P patients (case group) and 129 healthy volunteers (control group) were recruited for the study. The MTR A2756G, MTRR A66G, MTHFR C677T and MTHFR A1298C polymorphisms were assessed by polymerase chain reaction-restriction fragment length polymorphism. Haplotype analyses were performed with SHEsis software. Logistic regression analysis was used to evaluate the possible risk factors for NSCL/P. Generalized multifactor dimensionality reduction (GMDR) was applied to detect gene-gene interactions.

RESULTS

MTR A2756G, MTRR A66G, and MTHFR C677T gene polymorphisms were associated with the risk of NSCL/P (all p < 0.05). Logistic regression analysis revealed that MTR A2756G, MTR RA66G, and MTHFR C667T might increase the risk of NSCL/P (odds ratio [OR] = 0.270, 95% confidence interval [95% CI] = 0.106-0.689; OR = 0.159, 95% CI = 0.069-0.368; OR = 0.343, 95% CI = 0.139-0.844). The CA haplotype in the MTHFR gene may serve as a protective factor for NSCL/P (OR = 0.658, 95% CI = 0.470-0.923), and the TA haplotype might be a risk factor (OR = 2.001, 95% CI = 1.301-3.077). GMDR revealed that the optimal models were two- and four-dimensional models with prediction accuracies of 75.73% (p = 0.001) and 77.21% (p = 0.001) and the best cross-validation consistencies of 10/10 and 10/10, respectively.

CONCLUSION

MTR A2756G, MTRR A66G, and MTHFR C677T polymorphisms may be related to NSCL/P, and interactions were detected between the MTR A2756G, MTRR A66G, and MTHFR C677T and A1298C polymorphisms.