Reassessing the association: Evaluation of a polyalanine deletion variant of RUNX2 in non-syndromic sagittal and metopic craniosynostosis.

The RUNT-related transcription factor RUNX2 plays a critical role in osteoblast differentiation, and alterations to gene dosage cause distinct craniofacial anomalies. Uniquely amongst the RUNT-related family, vertebrate RUNX2 encodes a polyglutamine/polyalanine repeat (Gln23-Glu-Ala17 in humans), with the length of the polyalanine component completely conserved in great apes. Surprisingly, a frequent 6-amino acid deletion polymorphism, p.(Ala84_Ala89)del, occurs in humans (termed 11A allele), and a previous association study (Cuellar et al. Bone 137:115395;2020) reported that the 11A variant was significantly more frequent in non-syndromic sagittal craniosynostosis (nsSag; allele frequency [AF] = 0.156; 95% confidence interval [CI] 0.126-0.189) compared to non-syndromic metopic craniosynostosis (nsMet; AF = 0.068; 95% CI 0.045-0.098). However, the gnomAD v.2.1.1 control population used by Cuellar et al. did not display Hardy-Weinberg equilibrium, hampering interpretation. To re-examine this association, we genotyped the RUNX2 11A polymorphism in 225 individuals with sporadic nsSag as parent-child trios and 164 singletons with sporadic nsMet, restricting our analysis to individuals of European ancestry. We compared observed allele frequencies to the non-transmitted alleles in the parent-child trios, and to the genome sequencing data from gnomAD v.4, which display Hardy-Weinberg equilibrium. Observed AFs (and 95% CI) were 0.076 (0.053-0.104) in nsSag and 0.082 (0.055-0.118) in nsMet, compared with 0.062 (0.042-0.089) in non-transmitted parental alleles and 0.065 (0.063-0.067) in gnomAD v.4.0.0 non-Finnish European control genomes. In summary, we observed a non-significant excess, compared to gnomAD data, of 11A alleles in both nsSag (relative risk 1.18, 95% CI 0.83-1.67) and nsMet (relative risk 1.29, 95% CI 0.87-1.92), but we did not replicate the much higher excess of RUNX2 11A alleles in nsSag previously reported (p = 0.0001).

Pathogenic variants in the paired-related homeobox 1 gene (PRRX1) cause craniosynostosis with incomplete penetrance.

PURPOSE: Studies have previously implicated PRRX1 in craniofacial development, including demonstration of murine Prrx1 expression in the preosteogenic cells of the cranial sutures. We investigated the role of heterozygous missense and loss-of-function (LoF) variants in PRRX1 associated with craniosynostosis. METHODS: Trio-based genome, exome, or targeted sequencing were used to screen PRRX1 in patients with craniosynostosis; immunofluorescence analyses were used to assess nuclear localization of wild-type and mutant proteins. RESULTS: Genome sequencing identified 2 of 9 sporadically affected individuals with syndromic/multisuture craniosynostosis, who were heterozygous for rare/undescribed variants in PRRX1. Exome or targeted sequencing of PRRX1 revealed a further 9 of 1449 patients with craniosynostosis harboring deletions or rare heterozygous variants within the homeodomain. By collaboration, 7 additional individuals (4 families) were identified with putatively pathogenic PRRX1 variants. Immunofluorescence analyses showed that missense variants within the PRRX1 homeodomain cause abnormal nuclear localization. Of patients with variants considered likely pathogenic, bicoronal or other multisuture synostosis was present in 11 of 17 cases (65%). Pathogenic variants were inherited from unaffected relatives in many instances, yielding a 12.5% penetrance estimate for craniosynostosis. CONCLUSION: This work supports a key role for PRRX1 in cranial suture development and shows that haploinsufficiency of PRRX1 is a relatively frequent cause of craniosynostosis.

Unexpected role of SIX1 variants in craniosynostosis: expanding the phenotype of SIX1-related disorders.

BACKGROUND: Pathogenic heterozygous SIX1 variants (predominantly missense) occur in branchio-otic syndrome (BOS), but an association with craniosynostosis has not been reported. METHODS: We investigated probands with craniosynostosis of unknown cause using whole exome/genome (n=628) or RNA (n=386) sequencing, and performed targeted resequencing of SIX1 in 615 additional patients. Expression of SIX1 protein in embryonic cranial sutures was examined in the Six1nLacZ/+ reporter mouse. RESULTS: From 1629 unrelated cases with craniosynostosis we identified seven different SIX1 variants (three missense, including two de novo mutations, and four nonsense, one of which was also present in an affected twin). Compared with population data, enrichment of SIX1 loss-of-function variants was highly significant (p=0.00003). All individuals with craniosynostosis had sagittal suture fusion; additionally four had bilambdoid synostosis. Associated BOS features were often attenuated; some carrier relatives appeared non-penetrant. SIX1 is expressed in a layer basal to the calvaria, likely corresponding to the dura mater, and in the mid-sagittal mesenchyme. CONCLUSION: Craniosynostosis is associated with heterozygous SIX1 variants, with possible enrichment of loss-of-function variants compared with classical BOS. We recommend screening of SIX1 in craniosynostosis, particularly when sagittal±lambdoid synostosis and/or any BOS phenotypes are present. These findings highlight the role of SIX1 in cranial suture homeostasis.

Neoforehead Remodelling Techniques for Fronto-Orbital Advancement and Remodelling in the Oxford Craniofacial Unit: Lateral Remodelling and a Novel Central Self-Stabilizing S-Osteotomy Technique.

Fronto-orbital advancement and remodelling (FOAR) has undergone many modifications over the years, aimed at improving outcomes and reducing risks for patients. This work describes 2 techniques for remodelling the neoforehead used by the Oxford Craniofacial Unit since 1995: lateral remodelling and a central S-Osteotomy. Both methods adopt bone from the vertex as a neoforehead, but they differ in their techniques to adapt its shape to that of the newly remodelled orbital bandeau. The novel S-Osteotomy technique can be successfully applied to all FOAR procedures, irrespective of underlying synostosis and calvarial symmetry. It was originally developed for when 2 separate bony panels were required to create a neoforehead in asymmetrical cases, but was adopted for single panel neoforehead designs in metopic synostosis with the idea it may reduce temporal hollowing. An investigation of temporal hollowing in these patients who underwent either of the described methods was undertaken to assess this hypothesis with no statistically significant difference seen ( P =0.1111). Both techniques on average resulted in minimal hollowing that was not felt to require any revision, supporting the belief that temporal hollowing is a multifactorial issue. This work describes 2 successful methods of neoforehead remodelling and introduces the S-Osteotomy technique that can be applied in all FOAR procedures.

Parent and Patient Reported Outcomes for Head Shape in Children Undergoing Surgery for Single Suture Synostosis.

ABSTRACT: Assessing outcomes following surgery for single suture craniosynostosis is important to ensure minimum standards are being met, but also to compare results using different surgical techniques and treatment protocols. What constitutes an "outcome" and how this is measured remains a challenge, particularly when assessment should include consideration of aesthetic, functional, and psychological domains.The Oxford Craniofacial Unit has initiated routine collection of parents' and patients' ratings of 2 factors that are closely associated with psychological adjustment; how noticeable the child's headshape is and how much this bothers the parent and/or child. A brief Surgical Outcome Questionnaire is completed by parents and children (over 7 years) at their outpatient appointment; parents are also asked to rate the extent to which they feel surgery made a difference to their child's headshape.Data are presented for 519 parents and 248 children with single suture craniosynostosis who attended the Oxford Craniofacial Unit in 2018 and 2019; this represents over 80% of patients seen in the clinic indicating the questionnaire is acceptable for families and the potential for rapid, relevant data on a continuous basis. Analysis of the data is presented to demonstrate the utility of the Surgical Outcome Questionnaire in exploring the views of both parents and patients of the noticeability and level of concern about the child's headshape for different age groups and diagnoses.The Surgical Outcome Questionnaire provides a novel method of collecting routine data for patients across their craniofacial care pathway, using variables which are relevant and meaningful for patients and parents.

Cognitive, Behavioural, Speech, Language and Developmental Outcomes Associated with Pathogenic Variants in the ERF Gene.

ABSTRACT: Pathogenic variants of the ERF gene were previously associated with craniosynostosis, craniofacial dysmorphism and Chiari malformation. This study investigates cognitive, behavioural, speech, language, and developmental outcomes in the first 5 children identified at the Oxford Craniofacial Unit as having ERF- related craniosynostosis, together with three of their carrier parents.There were no consistent findings related to overall intelligence. However, a pattern of cognitive difficulties is described, which includes poor attention, impulsivity and difficulties with functional fine motor skills, such as handwriting. A high frequency of speech, language and communication difficulties was evident, which was most often related to early language difficulties, speech sound difficulties, hyponasal resonance and concern regarding social communication skills and emotional immaturity.It was common for these children to have needed input from ear, nose and throat services. Problems with tonsils and/or adenoids and/ or fluctuating conductive hearing loss were found which may be contributors to early speech, language and communication difficulties.The authors make recommendations regarding the need for formal assessment of a range of developmental aspects upon diagnosis of a pathogenic variant in the ERF gene. The aim of this report is to give clinical guidance to anyone who may have care of patients with the ERF -related mutation.

Psychosocial Impact of Coronal Access Scars in Craniosynostosis Procedures on Patients and Their Families.

ABSTRACT: The coronal incision is the mainstay for access in craniosynostosis surgery. Scarring is a common concern of parents whose children are offered an open procedure. To the author's knowledge, there are no previous studies looking at the psychosocial impact of scarring from coronal access incisions for craniosynostosis procedures. The author's study focused on patients undergoing procedures for nonsyndromic single-suture craniosynostosis.This study comprised 3 parts: worldwide survey regarding coronal access incisions for craniosynostosis surgery, questionnaire to determine the psychosocial impact of the scars on patients and their parents, and measurement of postoperative scars in craniosynostosis patients.Survey responses from 46 craniofacial centers worldwide revealed a zig-zag was the most commonly utilized incision. Seventy-two percent of survey responses reported problems with postoperative stretching of the scar; only 20% of centers reported formal data collection of whether families were affected by this.Psychology questionnaires revealed that the majority of patients and their parents were not bothered by the zig-zag coronal scars. Patient felt the scars were less noticeable than the parents. Parent perceptions improved with age and time postsurgery.Coronal access scars following craniosynostosis surgery appear to stretch more in the supra-auricular region compared with the midline.These findings are useful for the craniofacial multidisciplinary team to inform parents contemplating surgery and who may be concerned about the impact of the scar in the future.

Hearing, Speech, Language, and Communicative Participation in Patients With Apert Syndrome: Analysis of Correlation With Fibroblast Growth Factor Receptor 2 Mutation.

Apert syndrome (AS) is caused by the heterozygous presence of 1 of 2 specific missense mutations of the fibroblast growth factor receptor 2 (FGFR2) gene. The 2 adjacent substitutions, designated p.Ser252Trp (S252W) and p.Pro253Arg (P253R), account for more than 98% of cases. Previous research has identified elevated hearing difficulties and incidence of cleft palate in this population. However, the influence of FGFR2 genotype on the speech, language, and communicative participation of children with AS has yet to be examined. METHODS: A retrospective case note analysis was completed for all patients with a genetically-confirmed Apert mutation who attended the Oxford Craniofacial Unit over a 43-year period (1978-2020). Medical records were analyzed for speech, language, hearing, and communication data in detail. The therapy outcome measures, based on the World Health Organization International Classification of Functioning, Disability, and Health was used to classify patient's communicative participation. RESULTS: The authors identified 55 AS patients with genetically-confirmed mutation of the FGFR2 gene. One patient with a S252F mutation was excluded. There were 31 patients with the S252W mutation (male = 14; female = 17), age range of last hearing assessment (1-18 years), 64% (18/28) of patients had a cleft palate (including bifid uvula), 15 patients had conductive hearing loss, 1 patient had mixed hearing loss, 18 had otitis media with effusion (4 of whom had a cleft palate); 88% (21/24) of patients had receptive language difficulties, 88% (22/25) of patients had expressive language difficulties, 96% (27/28) of patients had a speech sound disorder. There were 23 patients with the P253R mutation (male = 13; female = 10); age range of last hearing assessment (1-13 years), 35% (8/23) patients had a cleft palate (including bifid uvula), 14 patients had a conductive hearing loss, 17 had otitis media with effusion (2 of whom had a cleft palate). Results indicated that 85% (17/20) of patients had receptive language difficulties, 80% (16/20) had expressive language difficulties, 100% (21/21) had a speech sound disorder. The S252W mutation was significantly-associated with the presence of cleft palate (including bifid uvula) (P  = 0.05).Data about the cumulative impact of all of these factors for communicative participation using the therapy outcome measures were available for 47 patients: (30 S252W; 17 P253R). Patients with a S252W mutation had significantly more severe difficulties with communicative participation when compared to individuals with a P253R mutation (P  = 0.0005) Cochran-Armitage trend test. CONCLUSIONS: Speech, language, communicative participation, and hearing difficulties are pervasive in patients with AS. The severity and functional impact of these difficulties are magnified in patients with the S252W mutation. Results reinforce the importance of considering patients with AS according to genotype.

Congenital Ossification Defects of the Frontal Bone: Description of a Novel Clinical Entity and the Management of Four Patients.

ABSTRACT: Embryologic development of the frontoorbital region is complex and is affected by a series of pathologies. These primarily represent failures of fusion at the interface between the frontal bones and the skull base or between the frontal bones themselves, or frontal bone defects in association with atypical craniofacial clefts or cutis aplasia. Isolated ossification defects in the frontal bones themselves are rare, with only 1 case having been previously reported. In that report, the defect was effectively managed with an alloplastic cranioplasty. However, long term results were not presented. Here, we describe 4 cases of isolated frontal bone aplasia their management using autologous bone.

Craniofacial Surgery-Related Hashtag Utilisation on Instagram.

BACKGROUND: Patients, parents, and carers are increasingly using social media to access and contribute to health information. There are currently 3.484 billion active social media users. Instagram is a primarily visual social media platform for sharing photographs and videos with currently over one billion monthly active users. Limited research has investigated the use of Instagram in healthcare contexts including plastic surgery, and in the treatment of specific conditions, such as fibromyalgia and scoliosis. This study aimed to investigate the use of Instagram in relation to craniofacial surgery. METHODS: The authors investigated the use of 12 Instagram craniofacial surgery-related hashtags. Quantitative and qualitative data were collected for each of the "top" nine posts associated with each hashtag. Duplicate posts, posts not in English and those not relevant to craniofacial surgery were excluded.Thematic analysis was then used to qualitatively evaluate the captions and comments of each of the nine "top" posts associated with each hashtag. RESULTS: A total number of 151,738 posts were identified using the 12 hashtags queried in the present study, with #craniofacial being the most popular hashtag (87% of posts). Parents (n = 25, 33%) and surgeons (n = 25, 33%) were responsible for the majority of posts. A heterogenous group were responsible for the remaining 34% of posts.Results indicated that parents and surgeons posted significantly different images (chi-squared with Yates correlation is 25.0519, P  < 0.00001). Parents' posts were predominantly images of their child/patients (n = 24) compared to posts about patients by surgeons (n = 6). Posts by surgeons were predominantly images of professionals (n = 14) compared to images of professionals posted by parents (n = 1).Results of qualitative analysis of captions of posts indicated a significant difference in themes that emerged between parents and surgeons; with surgeons largely using Instagram for information giving, and parents for sharing of experiences (chi-square (n = 108) = 40.83, P  < 0.00001).There was a significant difference (two-tailed t test, P  = 0.002) in engagement (measured by the number of likes on posts) on posts by parents (mean = 3778) compared to posts by surgeons (mean = 135.4). CONCLUSIONS: Results indicate that craniofacial-surgery related posts on Instagram provide a medium to allow individuals and families with rare disorders to connect and share their experiences. The use of Instagram to share information about craniofacial abnormalities via Instagram has the potential to be used by healthcare professionals to educate and support patients and families.

An Integrated Approach to the Management of Meningoencephalocoeles.

ABSTRACT: Meningoencephalocoeles are congenital herniations of meningeal and cerebral tissues through a cranial defect. They occur most commonly in South-East Asia, and are relatively rare amongst European ancestry populations, with an estimated prevalence of 1/40,000 live births. The treatment of congenital meningoencephalocoeles is primarily surgical and are best managed by dedicated multi-disciplinary craniofacial teams. The authors performed a retrospective case review of all primary meningoencephalocoeles managed in the Oxford University Hospitals NHS Foundation Trust between 1986 and 2012. Twenty-nine cases (13 frontal, 9 occipital, 2 parietal, and 5 basal) were included in this study. The median age at presentation was 11 months (range 0-60 years). Twenty-five cases presented with an external mass; 3 with recurrent meningitis and 1 with otorrhoea. Twenty-six cases underwent surgery, and 17 of these were managed by an integrated approach between 2 or more surgical specialties. Twenty out of 26 operations were performed via a transcranial approach. The authors describe a particularly complex case in order to highlight the challenges associated with management of meningoencephalocoeles, the surgical technique employed, and the importance of a multidisciplinary surgical approach. This is the largest reported case series of meningoencephalocoeles managed in a single hospital in the United Kingdom. Designated craniofacial units with access to multidisciplinary surgical specialties provide a safe and optimal setting for the management of meningoencephalocoeles.

The Sensitivity and Specificity of Parental Report of Concern for Identifying Language Disorder in Children With Craniosynostosis.

ABSTRACT: Many factors that may co-occur with craniosynostosis, such as oral structural anomalies, hearing impairment, visual impairment, cognitive difficulties and psychosocial factors, may predispose this population to communication difficulties. At the Oxford Craniofacial Unit, children's speech, language and communication are regularly monitored in accordance with a systematic developmental screening protocol developed by the Speech and Language Therapists in the 4 United Kingdom (UK) Highly Specialized Craniofacial Centers. In addition to routine assessments, when parents attend routine multidisciplinary clinic appointments, they are asked about their child's communication development, and whether they have any concerns.A retrospective review was undertaken of parental concerns about hearing, speech development, behavior, physical development, concentration, school and friendships as indicated by parents on the Oxford Craniofacial Unit Pre-Clinic Questionnaire. The areas of concern were then correlated with the results of a standardized, guided parent questionnaire about children's language development, (Children's Communication Checklist - 2 (CCC-2)), to determine whether parental concern alone is a reliable way of identifying whether patients require further assessment for Language Disorder associated with Craniosynostosis.Participants were parents of 89 monolingual English-speaking children with craniosynostosis (62 male; 27 female), age range four to 13 years (mean age = 8 years 7 months), receiving active care at the Oxford Craniofacial Unit (June 2017-July 2018). Results of the pre-clinic questionnaire indicated that 6% of parents had concerns about their child's communication development. Results of the CCC-2 indicated that 29/89 (32.6%) of children required further assessment for Language Disorder associated with Craniosynostosis. When language difficulties were identified on the CCC-2, only 14% (n = 4/29) parents indicated concern on the pre clinic questionnaire. Results indicated that parental concern about behavior was the most important factor in identifying language disorder (P = 0.023).Results reinforce that the pre-clinic questionnaire is useful for identifying areas of parental concern. Results also indicate that parental concern alone is not sufficient to identify language disorder, and that further, detailed assessment is warranted. The results are consistent with previously reported links between behavior and language in the general population.

Craniofacial Collaboration UK: Developmental Outcomes in 5-Year-Old Children With Sagittal Synostosis.

ABSTRACT: The Craniofacial Collaboration UK (CC-UK) is a joint initiative that seeks to address some of the limitations of previous developmental research with this patient group by providing systematically collected, robust data from clinically and chronologically homogenous representative samples of children. The current paper outlines the developmental outcomes at the age of 5 for children who had previously undergone primary surgery for single-suture sagittal synostosis (SS). It shows broad consistencies with the previous CC-UK work, indicating that the majority of children with SS will perform within the average range compared to peers across a number of developmental, behavioral and emotional domains. However, the group mean for children with SS indicates significantly greater difficulties with fine motor skills and hyperactivity, relative to normative data. Unexpectedly, children with SS had significantly better problem solving skills. While it is reassuring that the majority of children are broadly developing in line with their unaffected peers, these small but significant differences may be early indicators of some of the subtle difficulties documented in older children with craniosynostosis. Longitudinal follow up is therefore important to understand the developmental trajectory for children with SS and identification of potentially 'at risk' sub groups within this diagnostic cohort.

Neurodevelopmental, Cognitive, and Psychosocial Outcomes for Individuals With Pathogenic Variants in the TCF12 Gene and Associated Craniosynostosis.

ABSTRACT: Heterozygous mutations in the TCF12 gene were discovered in 2013 as a cause of craniosynostosis (CS). However, limited information regarding the behavioral phenotypic profile is available. Here the authors provide the first detailed study of the neurodevelopmental, cognitive, and psychosocial outcomes for patients with a pathogenic TCF12 variant and associated CS.A clinical casenote audit was conducted at the 4 UK highly specialized craniofacial centers. A total of 35 patients aged 18 months to 10 years with an identified TCF12 pathogenic variant and CS (bicoronal CS = 45.7%, unicoronal CS = 40.0%, multisuture = 14.3%) were included. Standardized screening and/or assessment of full-scale intelligence quotient, social communication, development, behavior, and self-concept were conducted.In the majority of cases, outcomes were consistent with age-related expectations. About 75% of patients demonstrated no delay across any early developmental domain, while 84.6% demonstrated full-scale intelligence quotient scores within 1 standard deviation of the population mean. Significant behavioral difficulties were demonstrated by parent reporters in 26.3% to 42.1% of cases (dependent upon domain). Clinically elevated social communication profiles were present in (41.7%) of parent-reported cases. Levels of self-concept (at age 10) were consistent with age-related normative data.Most patients with a TCF12 pathogenic variant had a mild behavioral and cognitive phenotype, although they may be at a slightly increased risk of social communication difficulties and psychosocial issues. Although not measured statistically, there were no clear associations between surgical history and cognitive, behavioral, or psychosocial outcomes. This paper highlights the need for robust integrated developmental assessment of all CS patients, particularly those with an identified syndrome.

Feeding, Communication, Hydrocephalus, and Intracranial Hypertension in Patients With Severe FGFR2-Associated Pfeiffer Syndrome.

BACKGROUND: Pfeiffer syndrome is associated with a genetic mutation of the FGFR2 (or more rarely, FGFR1) gene, and features the combination of craniosynostosis, midface hypoplasia, broad thumbs and broad great toes. Previous research has identified a wide spectrum of clinical phenotypes in patients with Pfeiffer syndrome. This study aimed to investigate the multifactorial considerations for speech, language, hearing and feeding development in patients with severe genetically-confirmed Pfeiffer syndrome. METHODS: A 23-year retrospective case-note review of patients attending the Oxford Craniofacial Unit was undertaken. Patients were categorized according to genotype. Patients with mutations located in FGFR1, or outside the FGFR2 IgIII domain-hotspot, or representing known Crouzon/Pfeiffer overlap substitutions were excluded. Twelve patients with severe FGFR2-associated Pfeiffer syndrome were identified. RESULTS: Patients most commonly had pansynostosis (n = 8) followed by bicoronal (n = 3), and bicoronal and sagittal synostosis (n = 1). Seven patients had a Chiari I malformation. Four patients had a diagnosis of epilepsy. Ten patients had with hydrocephalus necessitating ventriculoperitoneal shunt insertion.Feeding difficulties were common (n = 10/12) and multifactorial. In 5/12 cases, they were associated with pansynostosis, hydrocephalus, tracheostomy and tube feeding in infancy.Hearing data were available for 10 patients, of whom 9 had conductive hearing loss, and 8 required hearing aids. Results indicated that 3/4 patients had expressive language difficulties, 3/4 had appropriate receptive language skills. 6/12 patients had a speech sound disorder and abnormal resonance. CONCLUSION: This study has identified important speech, language, hearing and feeding issues in patients with severe FGFR2-associated Pfeiffer syndrome. Results indicate that a high rate of motor-based oral stage feeding difficulties, and pharyngeal stage swallowing difficulties necessitating regular review by specialist craniofacial speech and language therapists.

A genome-wide association study implicates the BMP7 locus as a risk factor for nonsyndromic metopic craniosynostosis.

Our previous genome-wide association study (GWAS) for sagittal nonsyndromic craniosynostosis (sNCS) provided important insights into the genetics of midline CS. In this study, we performed a GWAS for a second midline NCS, metopic NCS (mNCS), using 215 non-Hispanic white case-parent triads. We identified six variants with genome-wide significance (P ≤ 5 × 10-8): rs781716 (P = 4.71 × 10-9; odds ratio [OR] = 2.44) intronic to SPRY3; rs6127972 (P = 4.41 × 10-8; OR = 2.17) intronic to BMP7; rs62590971 (P = 6.22 × 10-9; OR = 0.34), located ~ 155 kb upstream from TGIF2LX; and rs2522623, rs2573826, and rs2754857, all intronic to PCDH11X (P = 1.76 × 10-8, OR = 0.45; P = 3.31 × 10-8, OR = 0.45; P = 1.09 × 10-8, OR = 0.44, respectively). We performed a replication study of these variants using an independent non-Hispanic white sample of 194 unrelated mNCS cases and 333 unaffected controls; only the association for rs6127972 (P = 0.004, OR = 1.45; meta-analysis P = 1.27 × 10-8, OR = 1.74) was replicated. Our meta-analysis examining single nucleotide polymorphisms common to both our mNCS and sNCS studies showed the strongest association for rs6127972 (P = 1.16 × 10-6). Our imputation analysis identified a linkage disequilibrium block encompassing rs6127972, which contained an enhancer overlapping a CTCF transcription factor binding site (chr20:55,798,821-55,798,917) that was significantly hypomethylated in mesenchymal stem cells derived from fused metopic compared to open sutures from the same probands. This study provides additional insights into genetic factors in midline CS.

Correction: SMAD6 variants in craniosynostosis: genotype and phenotype evaluation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

SMAD6 variants in craniosynostosis: genotype and phenotype evaluation.

PURPOSE: Enrichment of heterozygous missense and truncating SMAD6 variants was previously reported in nonsyndromic sagittal and metopic synostosis, and interaction of SMAD6 variants with a common polymorphism nearBMP2 (rs1884302) was proposed to contribute to inconsistent penetrance. We determined the occurrence of SMAD6 variants in all types of craniosynostosis, evaluated the impact of different missense variants on SMAD6 function, and tested independently whether rs1884302 genotype significantly modifies the phenotype. METHODS: We performed resequencing of SMAD6 in 795 unsolved patients with any type of craniosynostosis and genotyped rs1884302 in SMAD6-positive individuals and relatives. We examined the inhibitory activity and stability of SMAD6 missense variants. RESULTS: We found 18 (2.3%) different rare damaging SMAD6 variants, with the highest prevalence in metopic synostosis (5.8%) and an 18.3-fold enrichment of loss-of-function variants comparedwith gnomAD data (P < 10-7). Combined with eight additional variants, ≥20/26 were transmitted from an unaffected parent but rs1884302 genotype did not predict phenotype. CONCLUSION: Pathogenic SMAD6 variants substantially increase the risk of both nonsyndromic and syndromic presentations of craniosynostosis, especially metopic synostosis. Functional analysis is important to evaluate missense variants. Genotyping of rs1884302 is not clinically useful. Mechanisms to explain the remarkable diversity of phenotypes associated with SMAD6 variants remain obscure.

Implications for the Multi-Disciplinary Management of Children With Craniofrontonasal Syndrome.

The purpose of this retrospective study was to assess the genetic and phenotypic features of patients with craniofrontonasal syndrome (CFNS), and the implications of the condition for multidisciplinary management.The subjects were 25 female patients with a mutation of EFNB1, who presented to the Oxford Craniofacial Unit during a 38-year period. Medical records were reviewed for genetic and phenotypic information. Mean duration of follow-up was 12.6 years (range 0-30.7 years).This study examines neurodevelopment in constituent parts, with specific reference to speech, language, and cognition in relation to genotype. Three children had deletions extending beyond the EFNB1 gene; the 2 with available data presented with speech, language, or cognitive delay. The remaining 25 patients had intragenic mutations of EFNB1. Of these 25, those assessed in detail showed variable difficulties with speech and language development; 57% had receptive language difficulties (n = 4/7) and 88% had expressive language difficulties (n = 8/9). 55% presented with speech difficulties (n = 6/11). 2/3 patients with abnormal hearing had speech difficulties; 4/5 with normal hearing had normal speech development. Cognitive assessments indicated that IQ is variable; with full scale IQ ranging from 69 to 100.The complex, multifactorial presentation of patients with CFNS contributed to 41% (n = 7/17) of patients requiring additional educational support.Our results demonstrated significant multidisciplinary input is required, including Speech and Language Therapy, Plastic and Reconstructive Surgery, Genetics, Ear, Nose and Throat, Maxillofacial, Orthodontic, Orthopaedic, Clinical Psychology and Orthoptic teams. The results of this study reinforce the importance of multi-disciplinary long-term follow-up of children with CFNS.

Central Retinal Artery Occlusion Following Prone Transcranial Surgery for Craniosynostosis and Discussion of Risk Factors.

Vision loss is a known rare complication of prone positioning during surgery. Vision loss following prone surgery is most commonly attributed to direct pressure on the eye but can also be caused by central retinal artery occlusion (CRAO) in the absence of pressure on the eye. Central retinal artery occlusion has not been previously described following prone transcranial surgery for craniosynostosis. We present two cases of monocular CRAO following prone calvarial expansion. A multidisciplinary root cause analysis suggested that raised intracranial pressure and intraoperative tranexamic acid may have been risk factors for the development of CRAO in these cases as no conventional risk factors for CRAO following prone surgery were present. Because of this, we retrospectively reviewed all prone transcranial procedures performed at the Oxford Craniofacial Unit for the presence of raised intracranial pressure and intraoperative tranexamic acid use. A total of 662 prone procedures have been performed between 1994 and March, 2019. Tranexamic acid has been used routinely in all transcranial procedures since 2012 and in the last 311 consecutive prone cases. Fifty-one (7.7%) prone procedures were performed for raised intracranial pressure, and tranexamic acid was used in the 33 most recent of these. Since the implementation of standard intraoperative administration of tranexamic acid there have been 2 cases of CRAO following prone surgery. The overall incidence of CRAO was 0.3% but was 6% in the context of raised intracranial pressure and tranexamic acid use. Prone positioning raised intracranial pressure and tranexamic acid use together may represent a potent combination of risk factors for CRAO.