FAT4 identified as a potential modifier of orofacial cleft laterality

The Implications of Laterality in Unilateral Cleft Lip Reconstruction: A Global Survey of Cleft Surgeons

OBJECTIVE

To explore the impact of directional laterality in complete Unilateral Cleft Lip (UCL) amongst the global cleft surgeon community.

DESIGN

Cross-sectional survey study.

SETTING

Global distribution of online survey distributed in English and Spanish.

PARTICIPANTS

Cleft surgeons from around the world.

MAIN OUTCOME MEASURES

Survey participant perception of the impact of laterality on: (1) cleft presentation (2) surgical challenge and (3) surgical outcomes.

RESULTS

Responses were received from 453 cleft surgeons located in 54 countries around the world. 221 (49%) had previously considered differences in patients presenting with a left- versus right-sided UCL. 95 (21%) considered right-sided clefts more difficult to reconstruct, 37 (8%) reported left-sided clefts to be more difficult and 321 (71%) reported no difference in difficulty between the cleft sides. Higher volume cleft surgeons, characterised by those reporting cleft as their principal area of practice and performing >20 cleft operations per year, were more likely to have both previously considered differences in laterality in cleft and to report right-sided unilateral cleft lip to be more difficult to primarily reconstruct. 395 (87%) did not consider surgical outcomes to be influenced by cleft laterality.

CONCLUSIONS

This survey reports perceptions on cleft laterality from a large body of global surgeons and suggests a trend for increased difficulty in right-sided compared to left-sided cleft lip reconstruction, where such laterality-associated difficulty is perceived.

A multi-ancestry GWAS meta-analysis of facial features and its application in predicting archaic human features

Facial morphology, a complex trait influenced by genetics, holds great significance in evolutionary research. However, due to limited fossil evidence, the facial characteristics of Neanderthals and Denisovans have remained largely unknown. In this study, we conducted a large-scale multi-ethnic meta-analysis of the genome-wide association study (GWAS), including 9674 East Asians and 10,115 Europeans, quantitatively assessing 78 facial traits using 3D facial images. We identified 71 genomic loci associated with facial features, including 21 novel loci. We developed a facial polygenic score (FPS) that enables the prediction of facial features based on genetic information. Interestingly, the distribution of FPSs among populations from diverse continental groups exhibited relevant correlations with observed facial features. Furthermore, we applied the FPS to predict the facial traits of seven Neanderthals and one Denisovan using ancient DNA and aligned predictions with the fossil records. Our results suggested that Neanderthals and Denisovans likely shared similar facial features, such as a wider but shorter nose and a wider endocanthion distance. The decreased mouth width was characterized specifically in Denisovans. The integration of genomic data and facial trait analysis provides valuable insights into the evolutionary history and adaptive changes in human facial morphology.

Cleft lip Sidedness and the Association with Additional Congenital Malformations

OBJECTIVE

To investigate the association between the sidedness of orofacial clefts and additional congenital malformations.

DESIGN

Linkage of a national registry of cleft births to national administrative data of hospital admissions.

SETTING

National Health Service, England.

PARTICIPANTS

2007 children born with cleft lip ± alveolus (CL ± A) and 2724 with cleft lip and palate (CLP) born between 2000 and 2012.

MAIN OUTCOME MEASURE

The proportion of children with ICD-10 codes for additional congenital malformations by the sidedness (left, right or bilateral) of orofacial clefts.

RESULTS

For CL ± A phenotypes, there was no evidence for a difference in the prevalence of additional anomalies between left (22%, reference), right (22%, aOR 1.02, 95% CI 0.80 to 1.28; P = .90) and bilateral clefts (23%, aOR 1.09, 95% CI 0.75 to 1.57; P = .66). For CLP phenotypes, there was evidence of a lower prevalence of additional malformations in left (23%, reference) compared to right (32%, aOR 1.54, 95% CI 1.25 to 1.91; P < .001) and bilateral clefts (33%, aOR 1.64, 95% CI 1.35 to 1.99; P < .001).

CONCLUSIONS

The prevalence of additional congenital malformations was similar across sidedness subtypes with CL ± A phenotypes but was different for sidedness subtypes within CLP cases. These data support the hypothesis that CL ± A has a different underlying aetiology from CLP and that within the CLP phenotype, right sided CLP may lie closer in aetiology to bilateral CLP than it does to left sided CLP.

Should left- and right-sided unilateral cleft lip and palate patients be grouped together when reporting the outcomes?

OBJECTIVES

Investigate associations between cleft laterality in patients with non-syndromic unilateral cleft lip and palate (UCLP) and oral-health, dental-arch, speech, audiological, psychological and nasolabial-aesthetic outcomes.

METHODS

Secondary data analysis of the outcomes of 5-year-old children with non-syndromic complete UCLP identified from three studies: Cleft Collective (n = 155), Cleft Care UK (CCUK) (n = 266) and Clinical Standards Advisory Group (CSAG) study (n = 238). Outcome measures included occlusal assessment using the 5-year-old's index score, speech intelligibility rating using the CAPS-A Audit tool, audiological assessment using pure tone audiometry, nasolabial aesthetic assessment using the Asher-McDade tool, oral-health assessment using decayed, missing, filled teeth scores and parent-reported outcomes. Logistic regression with adjustment for age, sex and index-of-multiple-deprivation scores were performed.

RESULTS

No differences were found in patient-reported outcomes between the left and right clefts in the Cleft Collective study. From the CCUK study, right clefts had poorer speech (n = 236; 95% CI 1.09, 3.42; and P = .03) and hearing outcomes (n = 211; 95% CI 1.03, 3.43; P = .04). In the CSAG study, patients with left clefts were more likely to be teased (n = 213; 95% CI 0.26, 0.85; and P = .01).

CONCLUSION

Weak associations between cleft laterality, speech, hearing and psychological outcomes were found, however the findings were inconsistent across the studies. This study contributes to evidence of associations between laterality and outcomes in children born with UCLP.

The heterogeneous genetic architectures of orofacial clefts

Orofacial clefts (OFCs) are common, affecting 1:1000 live births. OFCs occur across a phenotypic spectrum - including cleft lip (CL), cleft lip and palate (CLP), or cleft palate (CP) - and can be further subdivided based on laterality, severity, or specific structures affected. Herein we review what is known about the genetic architecture underlying each of these subtypes, considering both shared and subtype-specific risks. While there are more known genetic similarities between CL and CLP than CP, recent research supports both shared and subtype-specific genetic risk factors within and between phenotypic classifications of OFCs. Larger sample sizes and deeper phenotyping data will be of increasing importance for the discovery of novel genetic risk factors for OFCs and various subtypes going forward.

Cleft Laterality Dental Arch Relationship Outcomes for Children with Unilateral Cleft Lip and Palate in New Zealand

OBJECTIVES

To investigate cleft laterality dental arch relationship outcomes of children with non-syndromic complete unilateral cleft lip and palate (UCLP) in New Zealand.

DESIGN

A retrospective nationwide study.

SETTINGS

Virtual 3D orthodontic study models collected prior to undertaking secondary alveolar bone grafting.

PARTICIPANTS

A total of 104 patients with UCLP (L = 80: R = 24).

OUTCOME MEASURES

Four calibrated assessors used the GOSLON Yardstick and 100 mm Visual Analogue Scale (VAS) to score the randomised models on 2 separate assessment sessions. Weighted Kappa were used to determine the intra/inter-rater reliability for the GOSLON and correlations for the VAS.

RESULTS

Intra-rater reliability ranged from 0.57-0.88 (GOSLON) and 0.45-0.93 (VAS). Inter-rater reliability ranged from 0.62-0.86 (GOSLON) and 0.64-0.93 (VAS).GOSLON scores for the left UCLP were 31.2% for good/very good; 26.3% for fair; 42.5% for poor/very poor while the right UCLP scored 8.3% for good/very good; 37.5% for fair; 54.2% for poor/very poor. The mean VAS for left and right UCLP were 53.4 (sd 22.5) and 44.6 (sd 17.1) respectively. Neither the GOSLON nor VAS differences reached statistical significance (both P = .08).

CONCLUSIONS

From a clinical perspective right UCLP had worse dental arch relationship outcomes, however, these differences failed to reach statistical significance. Further studies using larger sample sizes are required to determine if cleft laterality is an important consideration when investigating UCLP dental arch outcomes.

Sidedness in Unilateral Orofacial Clefts: A Systematic Scoping Review

OBJECTIVE

An overview of the literature relating to the sidedness of unilateral cleft lip with or without cleft palate to map current knowledge on the cause and impact of directional asymmetry.

DESIGN

Scoping review with a systematic search of Medline and Embase from inception to May 2023.

PATIENTS, PARTICIPANTS

Humans born with a left or right unilateral cleft lip with or without a cleft palate.

MAIN OUTCOME MEASURES

Cleft sidedness as a co-occurrence, an outcome or an exposure.

RESULTS

Forty studies were eligible for inclusion and confirmed the predilection for the occurrence of left sided cleft lips; 12 studies reported cleft sidedness co-occurring with another phenotype, 11 studies report sidedness as an outcome and 17 studies as an exposure. Phenotypes which were reported to co-occur with either left or right sided clefts included congenital dental anomalies, handedness and additional congenital anomalies. Variables investigated as a potential cause of left or right sided clefts as an outcome included chromosomal anomalies, genetic variants and environmental factors. Outcomes investigated in relation to cleft sidedness as an exposure included facial anatomical features, facial growth, educational attainment, functional and psychological characteristics. More studies showed worse outcomes in right sided clefts versus left sided clefts than vice versa, although studies were inconsistent, and a quality assessment was not performed.

CONCLUSIONS

The field of cleft sidedness research is expanding and there are promising early findings to differentiate cause and outcome by sidedness of the cleft.

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.

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.

Decoding the Human Face: Progress and Challenges in Understanding the Genetics of Craniofacial Morphology

Variations in the form of the human face, which plays a role in our individual identities and societal interactions, have fascinated scientists and artists alike. Here, we review our current understanding of the genetics underlying variation in craniofacial morphology and disease-associated dysmorphology, synthesizing decades of progress on Mendelian syndromes in addition to more recent results from genome-wide association studies of human facial shape and disease risk. We also discuss the various approaches used to phenotype and quantify facial shape, which are of particular importance due to the complex, multipartite nature of the craniofacial form. We close by discussing how experimental studies have contributed and will further contribute to our understanding of human genetic variation and then proposing future directions and applications for the field.

Genome-wide association study of multiethnic nonsyndromic orofacial cleft families identifies novel loci specific to family and phenotypic subtypes

Nonsyndromic orofacial clefts (OFCs) are among the most common craniofacial birth defects worldwide, and known to exhibit phenotypic and genetic heterogeneity. Cleft lip plus cleft palate (CLP) and cleft lip only (CL) are commonly combined together as one phenotype (CL/P), separately from cleft palate alone. In comparison, our study analyzes CL and CLP separately. A sample of 2218 CL and CLP cases, 4537 unaffected relatives of cases, and 2673 pure controls with no family history of OFC were selected from the Pittsburgh Orofacial Cleft (Pitt-OFC) multiethnic study.genome-wide association studies were run for seven specific phenotypes created based on the cleft type(s) observed within these families, as well as the combined CL/P phenotype. Five novel genome-wide significant associations, 3q29 (rs62284390), 5p13.2 (rs609659), 7q22.1 (rs6465810), 19p13.3 (rs628271), and 20q13.33 (rs2427238), and nine associations (p ≤ 1.0E-05) within previously confirmed OFC loci-PAX7, IRF6, FAM49A, DCAF4L2, 8q24.21, ARID3B, NTN1, TANC2 and the WNT9B:WNT3 gene cluster-were observed. We also found that single nucleotide polymorphisms within a subset of the associated loci, both previously known and novel, differ substantially in terms of their effects across cleft- or family-specific phenotypes, indicating not only etiologic differences between CL and CLP, but also genetic heterogeneity within each of the two OFC subtypes.

Genetic models and approaches to study orofacial clefts

INTRODUCTION

Orofacial clefts (OFCs) are common craniofacial birth defects with heterogeneous phenotype and etiology. Geneticists have applied nearly every available method and technology to further our understanding of the genetic architectures of OFCs.

OBJECTIVE

This review describes the evidence for a genetic etiology in OFCs, statistical genetic approaches employed to identify genetic causes, and how the results have shaped our current understanding of the genetic architectures of syndromic and nonsyndromic OFCs.

CONCLUSION

There has been rapid progress towards elucidating the genetic architectures of OFCs due to the availability of large collections of DNA samples from cases, controls, and families with OFCs and the consistent adoption of new methodologies and novel statistical approaches as they are developed. Genetic studies have identified rare and common variants influencing risk of OFCs in both Mendelian and complex forms of OFCs, blurring the distinctions traditional categories used in genetic studies and clinical medicine.