Incidence of neurological soft signs in children with isolated cleft of the lip or palate

Divergent growth of the transient brain compartments in fetuses with nonsyndromic isolated clefts involving the primary and secondary palate

Cleft lip/palate is a common orofacial malformation that often leads to speech/language difficulties as well as developmental delays in affected children, despite surgical repair. Our understanding of brain development in these children is limited. This study aimed to analyze prenatal brain development in fetuses with cleft lip/palate and controls. We examined in utero MRIs of 30 controls and 42 cleft lip/palate fetal cases and measured regional brain volumes. Cleft lip/palate was categorized into groups A (cleft lip or alveolus) and B (any combination of clefts involving the primary and secondary palates). Using a repeated-measures regression model with relative brain hemisphere volumes (%), and after adjusting for multiple comparisons, we did not identify significant differences in regional brain growth between group A and controls. Group B clefts had significantly slower weekly cerebellar growth compared with controls. We also observed divergent brain growth in transient brain structures (cortical plate, subplate, ganglionic eminence) within group B clefts, depending on severity (unilateral or bilateral) and defect location (hemisphere ipsilateral or contralateral to the defect). Further research is needed to explore the association between regional fetal brain growth and cleft lip/palate severity, with the potential to inform early neurodevelopmental biomarkers and personalized diagnostics.

The Brain in Oral Clefting: A Systematic Review With Meta-Analyses

Background

Neuroimaging of individuals with non-syndromic oral clefts have revealed subtle brain structural differences compared to matched controls. Previous studies strongly suggest a unified primary dysfunction of normal brain and face development which could explain these neuroanatomical differences and the neuropsychiatric issues frequently observed in these individuals. Currently there are no studies that have assessed the overall empirical evidence of the association between oral clefts and brain structure. Our aim was to summarize the available evidence on potential brain structural differences in individuals with non-syndromic oral clefts and their matched controls.

Methods

MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Web of Science and Embase were systematically searched in September 2020 for case-control studies that reported structural brain MRI in individuals with non-syndromic oral clefts and healthy controls. Studies of syndromic oral clefts were excluded. Two review authors independently screened studies for eligibility, extracted data and assessed risk of bias with the Newcastle-Ottawa Scale. Random effects meta-analyses of mean differences (MDs) and their 95% confidence intervals (95% CI) were performed in order to compare global and regional brain MRI volumes.

Results

Ten studies from 18 records were included in the review. A total of 741 participants were analyzed. A moderate to high risk of bias was determined for the included studies. The cerebellum (MD: -12.46 cm³, 95% CI: -18.26, -6.67, n = 3 studies, 354 participants), occipital lobes (MD: -7.39, 95% CI: -12.80, -1.99, n = 2 studies, 120 participants), temporal lobes (MD: -10.53 cm³, 95% CI: -18.23, -2.82, n = 2 studies, 120 participants) and total gray matter (MD: -41.14 cm³; 95% CI: -57.36 to -24.92, n = 2 studies, 172 participants) were significantly smaller in the cleft group compared to controls.

Discussion

There may be structural brain differences between individuals with non-syndromic oral clefts and controls based on the available evidence. Improvement in study design, size, methodology and participant selection could allow a more thorough analysis and decrease study heterogeneity.

Child development skills and language in toddlers with cleft lip and palate

INTRODUCTION

Children born with cleft lip and palate (CLP) are exposed to several risk factors for developmental delay.

METHODS

This cross-sectional and descriptive study compared the performance of gross motor, adaptive fine motor, social-personal and language skills in children with non-syndromic cleft lip and palate (age = 36-47 months, n = 30) matched as to chronological age and gender. The evaluation instruments were Denver Developmental Screening Test II and MacArthur Communicative Development Inventory - part D, employed for the receptive and expressive vocabulary checklist. Intergroup comparisons were performed using t tests and Chi-square tests. The Pearson correlation coefficient was used to verify the inter-category correlation (p ≤ 0.05).

RESULTS

There was statistically significant difference in gross motor, adaptive fine motor, and language skills, both in receptive and expressive aspects, in the comparison between groups. In the personal-social area, children with CLP presented performance below the expected, without statistically significant difference between groups.

CONCLUSIONS

Children with CLP are at risk for developmental disorders and should be monitored from early childhood to minimize the deleterious effects of this risk condition.

Toward an orofacial gene regulatory network

Orofacial clefting is a common birth defect with significant morbidity. A panoply of candidate genes have been discovered through synergy of animal models and human genetics. Among these, variants in interferon regulatory factor 6 (IRF6) cause syndromic orofacial clefting and contribute risk toward isolated cleft lip and palate (1/700 live births). Rare variants in IRF6 can lead to Van der Woude syndrome (1/35,000 live births) and popliteal pterygium syndrome (1/300,000 live births). Furthermore, IRF6 regulates GRHL3 and rare variants in this downstream target can also lead to Van der Woude syndrome. In addition, a common variant (rs642961) in the IRF6 locus is found in 30% of the world's population and contributes risk for isolated orofacial clefting. Biochemical studies revealed that rs642961 abrogates one of four AP-2alpha binding sites. Like IRF6 and GRHL3, rare variants in TFAP2A can also lead to syndromic orofacial clefting with lip pits (branchio-oculo-facial syndrome). The literature suggests that AP-2alpha, IRF6 and GRHL3 are part of a pathway that is essential for lip and palate development. In addition to updating the pathways, players and pursuits, this review will highlight some of the current questions in the study of orofacial clefting.

A LINE-1 insertion in DLX6 is responsible for cleft palate and mandibular abnormalities in a canine model of Pierre Robin sequence

Cleft palate (CP) is one of the most commonly occurring craniofacial birth defects in humans. In order to study cleft palate in a naturally occurring model system, we utilized the Nova Scotia Duck Tolling Retriever (NSDTR) dog breed. Micro-computed tomography analysis of CP NSDTR craniofacial structures revealed that these dogs exhibit defects similar to those observed in a recognizable subgroup of humans with CP: Pierre Robin Sequence (PRS). We refer to this phenotype in NSDTRs as CP1. Individuals with PRS have a triad of birth defects: shortened mandible, posteriorly placed tongue, and cleft palate. A genome-wide association study in 14 CP NSDTRs and 72 unaffected NSDTRs identified a significantly associated region on canine chromosome 14 (24.2 Mb–29.3 Mb; p_raw = 4.64×10⁻¹⁵). Sequencing of two regional candidate homeobox genes in NSDTRs, distal-less homeobox 5 (DLX5) and distal-less homeobox 6 (DLX6), identified a 2.1 kb LINE-1 insertion within DLX6 in CP1 NSDTRs. The LINE-1 insertion is predicted to insert a premature stop codon within the homeodomain of DLX6. This prompted the sequencing of DLX5 and DLX6 in a human cohort with CP, where a missense mutation within the highly conserved DLX5 homeobox of a patient with PRS was identified. This suggests the involvement of DLX5 in the development of PRS. These results demonstrate the power of the canine animal model as a genetically tractable approach to understanding naturally occurring craniofacial birth defects in humans.

Cleft palate is one of the most commonly occurring birth defects in children, and yet its cause is not completely understood. In order to better understand cleft palate we have turned to man's best friend, the domestic dog. Common breeding practices have made the dog a unique animal model to help understand the genetic basis of naturally occurring birth defects. A genome-wide association study of Nova Scotia Duck Tolling Retrievers with naturally occurring cleft palate led to the investigation of two homeobox genes, DLX5 and DLX6. Dogs with this mutation also have a shortened lower jaw, which resembles those who have Pierre Robin Sequence (PRS). Investigation into people with PRS identifies a mutation within a highly conserved and functional region of DLX5 that may contribute to the development of PRS. This exemplifies how the dog will help us better understand common birth defects.

Cleft lip and palate results from Hedgehog signaling antagonism in the mouse: Phenotypic characterization and clinical implications

BACKGROUND

The Hedgehog (Hh) pathway provides inductive signals critical for developmental patterning of the brain and face. In humans and in animal models interference with this pathway yields birth defects, among the most well-studied of which fall within the holoprosencephaly (HPE) spectrum.

METHODS

Timed-pregnant C57Bl/6J mice were treated with the natural Hh signaling antagonist cyclopamine by subcutaneous infusion from gestational day (GD) 8.25 to 9.5, or with a potent cyclopamine analog, AZ75, administered by oral gavage at GD 8.5. Subsequent embryonic morphogenesis and fetal central nervous system (CNS) phenotype were respectively investigated by scanning electron microscopy and high resolution magnetic resonance imaging (MRI).

RESULTS

In utero Hh signaling antagonist exposure induced a spectrum of craniofacial and brain malformations. Cyclopamine exposure caused lateral cleft lip and palate (CLP) defects attributable to embryonic deficiency of midline and lower medial nasal prominence tissue. The CLP phenotype was accompanied by olfactory bulb hypoplasia and anterior pituitary aplasia, but otherwise grossly normal brain morphology. AZ75 exposure caused alobar and semilobar HPE with associated median facial deficiencies. An intermediate phenotype of median CLP was produced infrequently by both drug administration regimens.

CONCLUSIONS

The results of this study suggest that interference with Hh signaling should be considered in the CLP differential and highlight the occurrence of CNS defects that are expected to be present in a cohort of patients having CLP. This work also illustrates the utility of fetal MRI-based analyses and establishes a novel mouse model for teratogen-induced CLP.