Craniosynostosis syndromes: from genes to premature fusion of skull bones

Emphasis on Early Prenatal Diagnosis and Perinatal Outcomes Analysis of Apert Syndrome

Apert syndrome is an inherited condition with autosomal dominant transmission. It is also known as acrocephalosyndactyly type I, being characterized by a syndrome of craniosynostosis with abnormal head shape, facial anomalies (median hypoplasia), and limb deformities (syndactyly, rhizomelic shortening). The association can suspect the prenatal diagnosis of these types of anomalies. The methodology consisted of revising the literature, by searching the PubMed/Medline database in which 27 articles were selected and analyzed, comprising 32 cases regarding the prenatal diagnosis of Apert syndrome. A series of ultrasound parameters, the anatomopathological abnormalities found, the obstetric results, and the genetic tests were followed. The distribution of imaging results (US, MRI) identified in the analyzed cases was as follows: skull-shaped abnormalities were evident in 96.8% of cases, facial abnormalities (hypertelorism 43.7%, midface hypoplasia 25%, proptosis 21.8%), syndactyly in 87.5%, and cardiovascular abnormalities in 9.3%. The anomalies detected by the ultrasound examination of the fetus were confirmed postnatally by clinical or gross evaluation or imaging. The management of these cases requires an early diagnosis, an evaluation of the severity of the cases, and appropriate parental counseling.

Multidisciplinary Rehabilitation Approach to the Maxillo-Facial Complications of Crouson’s Disease: Case Report and Review

Background:

Craniofacial anomalies present a challenge to all health care practitioners since they necessitate long-term team follow-up, which is difficult to achieve outside of a major center where craniofacial anomalies teams normally collaborate.

Objectives:

The current review with an illustrative case focuses on the representation and review of Crouzon syndrome and its maxillofacial implications. Review of different varieties of gene mutations that produce craniosynostosis syndromes were discussed and focused on seven clinically distinct craniosynostosis syndromes that are precipitated by the mutation in one or more of the fibroblast growth factor receptors genes which affected the maxillofacial region.

Case presentation:

A complete clinical and radiographic case scenario of a patient suffering from Crouzon syndrome was presented, and discussion of the various disciplines and techniques used along the way to achieve the best results, as well as how team collaboration and patient compliance led to the best results were represented. The presented case was treated with orthodontic treatment, Le Fort-I osteotomy, and Le Fort-III osteotomy with extraoral distraction osteogenesis.

Conclusion:

The combination of different orthognathic surgery alternatives (Le Fort-III and Le Fort-I) with distraction osteogenesis and orthodontic treatment produced excellent outcomes with few complications, and the patient was extremely satisfied and cooperative. Early and thorough team-based care for Crouzon syndrome patients should be accessible at specialized craniofacial centers.

Examining the Relationship Between Wound Complications and the Use of Resorbable Plates in Cranial Vault Reconstruction

BACKGROUND

Resorbable plates are commonly used in cranial vault reconstruction surgery. There are few published papers examining their safety profile. The authors examined the prevalence of wound complications associated with the use of resorbable plates (Inion CPS Fixation System) in pediatric patients undergoing cranial vault reconstruction.

METHODS

A retrospective review of patients (n = 182) who underwent cranial vault reconstruction using resorbable plate fixation was undertaken. All procedures were performed by a single Craniofacial Surgeon at the National Pediatric Craniofacial Center from 2008 to 2016. Wound complications were identified from a prospectively maintained database and medical note review. Several key patient characteristics and surgical variables were also recorded and tested for associations with wound complications.

RESULTS

A total of 58.8% (107 of 182) of patients were male with a median age at surgery of 16.2 months. Overall, 12.1% (22 of 182) experienced a postoperative wound complication requiring hospital admission. A total of 2.73% (5 of 182) of the patients that returned to theatre had remnants of plates removed. The authors had a mean time from primary operation to secondary reoperation of 103 days. In univariate statistical analysis, females were more likely to develop a wound complication. However, in stratified analyses excluding patients with an underlying genetic syndrome, increasing age, and lower weight but not gender were associated with wound complications.

CONCLUSIONS

A 12.1% (22 of 182) wound complication rate with the use of the Inion CPS Fixation System was observed. Inion plates appear to have an equivalent safety profile to other fixation devices. Increasing age and lower weight were associated with an increased risk of wound complications in nonsyndromic patients.

Neuro-Ophthalmological Manifestations of Craniosynostosis: Current Perspectives

Craniosynostosis, a premature fusion of cranial sutures that can be isolated or syndromic, is a congenital defect with a broad, multisystem clinical spectrum. The visual pathway is prone to derangements in patients with craniosynostosis, particularly in syndromic cases, and there is a risk for permanent vision loss when ocular disease complications are not identified and properly treated early in life. Extensive advancements have been made in our understanding of the etiologies underlying vision loss in craniosynostosis over the last 20 years. Children with craniosynostosis are susceptible to interruptions in visual input arising from strabismus, refractive errors, and corneal damage; any of these aberrations can result in understimulation of the visual cortex during childhood neurodevelopment and permanent amblyopia. Elevated intracranial pressure resulting from abnormal cranial shape or volume can lead to papilledema and, ultimately, optic atrophy and vision loss. A pediatric ophthalmologist is a crucial component of the multidisciplinary care team that should be involved in the care of craniosynostosis patients and consistent ophthalmologic follow-up can help minimize the risk to vision posed by such entities as papilledema and amblyopia. This article aims to review the current understanding of neuro-ophthalmological manifestations in craniosynostosis and explore diagnostic and management considerations for the ophthalmologist taking care of these patients.

Outcomes following Craniosynostosis Surgery at a Tertiary Care Center in the Middle East

BACKGROUND

Despite advancements in craniosynostosis surgery, open surgical approaches remain crucial for the management of infants >6 months of age and in those with complex synostosis. The clinical features of craniosynostosis remain poorly characterized in the Middle East. This study sought to assess the clinical features and outcomes of infants undergoing craniosynostosis surgery at a tertiary care center in Lebanon.

METHODS

A retrospective review was performed of all patients who underwent craniosynostosis surgery from December 2006 to December 2018 at the American University of Beirut Medical Center, Lebanon. Clinicodemographic characteristics, complications, and recurrence outcomes were recorded and evaluated using descriptive statistics.

RESULTS

Thirty-five infants met the inclusion criteria, with a mean age of 9.0 ± 4.0 months. The most common site of suture involvement was metopic (28.6%), followed by unilateral coronal (25.7%), sagittal (20.0%), bicoronal (8.6%), and multiple sites (17.1%). Five patients (14.3%) had syndromic synostosis. Median estimated blood loss was 200 mL, and median volume of transfused packed red blood cells was 180 mL. Two patients (5.7%) experienced postoperative complications, including postoperative blood transfusion (n = 1)and wire protrusion requiring removal (n = 1). Three patients (8.6%) required reoperation: 2 (5.7%) for resynostosis and 1 for traumatic fracture repair. Caregivers of all patients reported high satisfaction with cosmetic outcomes 4 weeks postoperatively.

CONCLUSIONS

With appropriate perioperative precautions, open craniosynostosis surgery can be performed with minimal complications, low recurrence rates, and satisfactory cosmetic outcomes. Additional population-level data are needed to better characterize craniosynostosis patterns and outcomes in the Middle East.

An FDA-Approved Drug Screen for Compounds Influencing Craniofacial Skeletal Development and Craniosynostosis

Neural crest stem/progenitor cells (NCSCs) populate a variety of tissues, and their dysregulation is implicated in several human diseases including craniosynostosis and neuroblastoma. We hypothesised that small molecules that inhibit NCSC induction or differentiation may represent potential therapeutically relevant drugs in these disorders. We screened 640 FDA-approved compounds currently in clinical use for other conditions to identify those which disrupt development of NCSC-derived skeletal elements that form the zebrafish jaw. In the primary screen, we used heterozygous transgenic sox10:gfp zebrafish to directly visualise NCSC-derived jaw cartilage. We noted partial toxicity of this transgene in relation to jaw patterning, suggesting that our primary screen was sensitised for NCSC defects, and we confirmed 10 novel, 4 previously reported, and 2 functional analogue drug hits in wild-type embryos. Of these drugs, 9/14 and 7/14, respectively, are known to target pathways implicated in osteoarthritis pathogenesis or to cause reduced bone mineral density/increased fracture risk as side effects in patients treated for other conditions, suggesting that our screen enriched for pathways targeting skeletal tissue homeostasis. We selected one drug that inhibited NCSC induction and one drug that inhibits bone mineralisation for further detailed analyses which reflect our initial hypotheses. These drugs were leflunomide and cyclosporin A, respectively, and their functional analogues, teriflunomide and FK506 (tacrolimus). We identified their critical developmental windows of activity, showing that the severity of defects observed related to the timing, duration, and dose of treatment. While leflunomide has previously been shown to inhibit NCSC induction, we demonstrate additional later roles in cartilage remodelling. Both drugs altered expression of extracellular matrix metalloproteinases. As proof-of-concept, we also tested drug treatment of disease-relevant mammalian cells. While leflunomide treatment inhibited the viability of several human NCSC-derived neuroblastoma cell lines coincident with altered expression of genes involved in ribosome biogenesis and transcription, FK506 enhanced murine calvarial osteoblast differentiation and prevented fusion of the coronal suture in calvarial explants taken from Crouzon syndrome mice.

Adeno-Associated Virus-Mediated RNAi against Mutant Alleles Attenuates Abnormal Calvarial Phenotypes in an Apert Syndrome Mouse Model

Apert syndrome (AS), the most severe form of craniosynostosis, is caused by missense mutations including Pro253Arg(P253R) of fibroblast growth factor receptor 2 (FGFR2), which leads to enhanced FGF/FGFR2-signaling activity. Surgical correction of the deformed skull is the typical treatment for AS. Because of constant maldevelopment of sutures, the corrective surgery is often executed several times, resulting in increased patient challenge and complications. Biological therapies targeting the signaling of mutant FGFR2 allele, in combination with surgery, may bring better outcome. Here we screened and found a small interfering RNA (siRNA) specifically targeting the Fgfr2-P253R allele, and we revealed that it inhibited osteoblastic differentiation and matrix mineralization by reducing the signaling of ERK1/2 and P38 in cultured primary calvarial cells and calvarial explants from Apert mice (Fgfr2^+/P253R). Furthermore, AAV9 carrying short hairpin RNA (shRNA) (AAV9-Fgfr2-shRNA) against mutant Fgfr2 was delivered to the skulls of AS mice. Results demonstrate that AAV9-Fgfr2-shRNA attenuated the premature closure of coronal suture and the decreased calvarial bone volume of AS mice. Our study provides a novel practical biological approach, which will, in combination with other therapies, including surgeries, help treat patients with AS while providing experimental clues for the biological therapies of other genetic skeletal diseases.

Choanal Atresia and Craniosynostosis: Development and Disease

A number of textbooks, review articles, and case reports highlight the potential comorbidity of choanal atresia in craniosynostosis patients. However, the lack of a precise definition of choanal atresia within the current craniosynostosis literature and widely varying methods of detection and diagnosis have produced uncertainty regarding the true coincidence of these conditions. The authors review the anatomy and embryologic basis of the human choanae, provide an overview of choanal atresia, and analyze the available literature that links choanal atresia and craniosynostosis. Review of over 50 case reports that describe patients diagnosed with both conditions reveals inconsistent descriptions of choanal atresia and limited use of definitive diagnostic methodologies. The authors further present preliminary analysis of three-dimensional medical head computed tomographic scans of children diagnosed with craniosynostosis syndromes (e.g., Apert, Pfeiffer, Muenke, and Crouzon) and typically developing children and, although finding no evidence of choanal atresia, report the potentially reduced nasal airway volumes in children diagnosed with Apert and Pfeiffer syndromes. A recent study of the Fgfr2c Crouzon/Pfeiffer syndrome mouse model similarly found a significant reduction in nasal airway volumes in littermates carrying this FGFR2 mutation relative to unaffected littermates, without detection of choanal atresia. The significant correlation between specific craniosynostosis syndromes and reduced nasal airway volume in mouse models for craniosynostosis and human pediatric patients indicates comorbidity of choanal and nasopharyngeal dysmorphologies and craniosynostosis conditions. Genetic, developmental, and epidemiologic sources of these interactions are areas particularly worthy of further research.

Deformed Skull Morphology Is Caused by the Combined Effects of the Maldevelopment of Calvarias, Cranial Base and Brain in FGFR2-P253R Mice Mimicking Human Apert Syndrome

Apert syndrome (AS) is a common genetic syndrome in humans characterized with craniosynostosis. Apert patients and mouse models showed abnormalities in sutures, cranial base and brain, that may all be involved in the pathogenesis of skull malformation of Apert syndrome. To distinguish the differential roles of these components of head in the pathogenesis of the abnormal skull morphology of AS, we generated mouse strains specifically expressing mutant FGFR2 in chondrocytes, osteoblasts, and progenitor cells of central nervous system (CNS) by crossing Fgfr2^+/P253R-Neo mice with Col2a1-Cre, Osteocalcin-Cre (OC-Cre), and Nestin-Cre mice, respectively. We then quantitatively analyzed the skull and brain morphology of these mutant mice by micro-CT and micro-MRI using Euclidean distance matrix analysis (EDMA). Skulls of Col2a1-Fgfr2^+/P253R mice showed Apert syndrome-like dysmorphology, such as shortened skull dimensions along the rostrocaudal axis, shortened nasal bone, and evidently advanced ossification of cranial base synchondroses. The OC-Fgfr2^+/P253R mice showed malformation in face at 8-week stage. Nestin-Fgfr2^+/P253R mice exhibited increased dorsoventral height and rostrocaudal length on the caudal skull and brain at 8 weeks. Our study indicates that the abnormal skull morphology of AS is caused by the combined effects of the maldevelopment in calvarias, cranial base, and brain tissue. These findings further deepen our knowledge about the pathogenesis of the abnormal skull morphology of AS, and provide new clues for the further analyses of skull phenotypes and clinical management of AS.

Fibroblast growth factor receptor signaling in hereditary and neoplastic disease: biologic and clinical implications

Fibroblast growth factors (FGFs) and their receptors (FGFRs) are transmembrane growth factor receptors with wide tissue distribution. FGF/FGFR signaling is involved in neoplastic behavior and also development, differentiation, growth, and survival. FGFR germline mutations (activating) can cause skeletal disorders, primarily dwarfism (generally mutations in FGFR3), and craniofacial malformation syndromes (usually mutations in FGFR1 and FGFR2); intriguingly, some of these activating FGFR mutations are also seen in human cancers. FGF/FGFR aberrations reported in cancers are mainly thought to be gain-of-function changes, and several cancers have high frequencies of FGFR alterations, including breast, bladder, or squamous cell carcinomas (lung and head and neck). FGF ligand aberrations (predominantly gene amplifications) are also frequently seen in cancers, in contrast to hereditary syndromes. There are several pharmacologic agents that have been or are being developed for inhibition of FGFR/FGF signaling. These include both highly selective inhibitors as well as multi-kinase inhibitors. Of note, only four agents (ponatinib, pazopanib, regorafenib, and recently lenvatinib) are FDA-approved for use in cancer, although the approval was not based on their activity against FGFR. Perturbations in the FGFR/FGF signaling are present in both inherited and malignant diseases. The development of potent inhibitors targeting FGF/FGFR may provide new tools against disorders caused by FGF/FGFR alterations.

Effects of Citalopram on Sutural and Calvarial Cell Processes

The use of selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression during pregnancy is suggested to increase the incidence of craniofacial abnormalities including craniosynostosis. Little is known about this mechanism, however based on previous data we propose a mechanism that affects cell cycle. Excessive proliferation, and reduction in apoptosis may lead to hyperplasia within the suture that may allow for differentiation, bony infiltration, and fusion. Here we utilized in vivo and in vitro analysis to investigate this proposed phenomenon. For in vivo analysis we used C57BL–6 wild-type breeders treated with a clinical dose of citalopram during the third trimester of pregnancy to produce litters exposed to the SSRI citalopram in utero. At post-natal day 15 sutures were harvested from resulting pups and subjected to histomorphometric analysis for proliferation (PCNA) and apoptosis (TUNEL). For in vitro studies, we used mouse calvarial pre-osteoblast cells (MC3T3-E1) to assess proliferation (MTS), apoptosis (Caspase 3/7-activity), and gene expression after exposure to titrated doses of citalopram. In vivo analysis for PCNA suggested segregation of effect by location, with the sagittal suture, showing a statistically significant increase in proliferative response. The coronal suture was not similarly affected, however there was a decrease in apoptotic activity at the dural edge as compared to the periosteal edge. No differences in apoptosis by suture or area due to SSRI exposure were observed. In vitro results suggest citalopram exposure increased proliferation and proliferative gene expression, and decreased apoptosis of the MC3T3-E1 cells. Decreased apoptosis was not confirmed in vivo however, an increase in proliferation without a concomitant increase in apoptosis is still defined as hyperplasia. Thus prenatal SSRI exposure may exert a negative effect on post-natal growth through a hyperplasia effect at the cranial growth sites perhaps leading to clinically significant craniofacial abnormalities.

Morphology of the foramen magnum in syndromic and non-syndromic brachycephaly

PURPOSE

The shape and size of the foramen magnum (FM) can be altered in craniosynostoses. However, few studies have investigated these changes. In this paper, we investigate the morphology of the foramen magnum in syndromic and non-syndromic brachycephaly.

METHODS

Surface area, anteroposterior (AP) diameter, and transverse diameters of the FM were measured on high-resolution CT scans in children with Crouzon (25), Pfeiffer (21), Apert (26), Saethre-Chotzen (7) syndromes, and isolated bicoronal synostosis (9) and compared to an age-matched control group (30).

RESULTS

A significantly smaller FM surface area was observed in Crouzon (6.3 ± 1.7 cm(2)) and Pfeiffer (6.4 ± 2.3 cm(2)) syndromes as compared to the control group (7.4 ± 1.3 cm(2), p = 0.006 and p = .017, respectively). In comparison to the control group, no statistically significant alteration in FM surface area was noted in patients with Apert, Saethre-Chotzen, or isolated bicoronal synostosis (p = 0.37, p = 0.71, p = 0.40 respectively). The transverse diameter of FM was significantly smaller in Crouzon, Pfeiffer, and Apert syndromes compared to the control group (p = 0.005, p = 0.002, p = 0.03 respectively). In Saethre-Chotzen and isolated bicoronal synostosis, no difference in transverse diameter was demonstrated. Among all groups, only Crouzon syndrome showed reduced anteroposterior diameter as compared to controls (p = 0.005). In Pfeiffer and Apert syndromes, there was elongation of the shape of the FM with a relatively narrowed width as demonstrated in a significantly increased AP to transverse diameter ratio (p = 0.002 and p = 0.019, respectively).

DISCUSSION AND CONCLUSIONS

The FM shape and area is significantly altered in fibroblast growth factor receptor (FGFR)-related brachycephaly syndromes (Crouzon, Pfeiffer, and Apert), whereas in patients with Saethre-Chotzen syndrome (TWIST-1 mutation) and isolated non-syndromic bicoronal synostosis, the shape and mean FM area was not statistically different from that of normals. This study brings to light the important role of FGFRs on FM growth and shape. TWIST-1 mutation (Saethre-Chotzen syndrome) does not appear to have an important effect in shaping the FM.

Inhibited Wnt signaling causes age-dependent abnormalities in the bone matrix mineralization in the Apert syndrome FGFR2(S252W/+) mice

Apert syndrome (AS) is a type of autosomal dominant disease characterized by premature fusion of the cranial sutures, severe syndactyly, and other abnormalities in internal organs. Approximately 70% of AS cases are caused by a single mutation, S252W, in fibroblast growth factor receptor 2 (FGFR2). Two groups have generated FGFR2 knock-in mice Fgfr2S252W/+ that exhibit features of AS. During the present study of AS using the Fgfr2S252W/+ mouse model, an age-related phenotype of bone homeostasis was discovered. The long bone mass was lower in 2 month old mutant mice than in age-matched controls but higher in 5 month old mutant mice. This unusual phenotype suggested that bone marrow-derived mesenchymal stem cells (BMSCs), which are vital to maintain bone homeostasis, might be involved. BMSCs were isolated from Fgfr2S252W/+ mice and found that S252W mutation could impair osteogenic differentiation BMSCs but enhance mineralization of more mature osteoblasts. A microarray analysis revealed that Wnt pathway inhibitors SRFP1/2/4 were up-regulated in mutant BMSCs. This work provides evidence to show that the Wnt/β-catenin pathway is inhibited in both mutant BMSCs and osteoblasts, and differentiation defects of these cells can be ameliorated by Wnt3a treatment. The present study suggested that the bone abnormalities caused by deregulation of Wnt pathway may underlie the symptoms of AS.

Current Updates on Choanal Atresia

Choanal atresia (CA) is a relatively uncommon but well-recognized condition characterized by the anatomical closure of the posterior choanae in the nasal cavity. Since the original description back in the early eighteenth century, there have been controversies regarding its exact pathogenesis, the optimal surgical approach, and the use of adjunct treatments such as post-surgical stenting and anti-neoplastic agents, despite of abundant literature available. The emergence and development of new technologies play a significant role in the management of this condition. This review provides a comprehensive clinical update on CA and identifies areas for future study based on the existing available literature.

Change in Mandibular Position in Patients With Syndromic Craniosynostosis After Midfacial Advancement With Distraction Osteogenesis

OBJECTIVE

Characterize mandibular morphology in patients with syndromic craniosynostosis and document changes in mandibular position following midfacial advancement using distraction osteogenesis (DO).

DESIGN

Retrospective chart review and analysis of cephalometric radiographs.

SETTING

Tertiary care center.

PATIENTS

Patients with syndromic craniosynostosis who had midfacial advancement with DO at Boston Children's Hospital between 2000 and 2012. Mandibular morphology was characterized in 26 patients (15 boys and 11 girls) with a mean age of 11 years, 9 months. Pre- and postoperative analyses were performed for 17 (10 boys and 7 girls) of the 26 patients with a mean age of 11 years, 9 months.

MAIN OUTCOME MEASURES

Mandibular morphology and mandibular position. Data were compared to standard data from the Michigan Growth Study.

RESULTS

Comparison of preoperative mandibular measurements to standard data showed that patients with syndromic craniosynostosis have a shorter mandibular body and length and an obtuse gonial angle. Comparison of pre- and postoperative cephalograms showed that, following midfacial advancement with DO, the maxilla moved forward and the mandible moved backward and downward.

CONCLUSIONS

Patients with syndromic craniosynostosis have a smaller mandible length and obtuse gonial angle. Correction of midfacial hypoplasia with DO results in inferior and posterior mandibular movement. Clinicians can use this information to counsel patients regarding anticipated changes in facial profile and the need for adjunct procedures.

Descriptive and risk factor analysis for choanal atresia: The National Birth Defects Prevention Study, 1997-2007

Choanal atresia causes serious posterior nasal obstruction. This defect is the leading cause of nasal surgery in newborns, although its etiology is largely unknown. Data from the National Birth Defects Prevention Study, a population-based case-control study, were used to examine associations between maternal self-reports of exposures and occurrence of choanal atresia in their offspring. Overall, 117 case and 8350 control mothers with deliveries from 1997 through 2007 provided telephone interview reports of pre-pregnancy (one year before conception) and periconceptional (one month before through three months after conception) exposures. The exposures analyzed were pre-pregnancy dietary intake, pre-pregnancy and periconceptional caffeine consumption, and periconceptional cigarette smoking, alcohol drinking, and medication use. Independent associations between each exposure and all choanal atresia cases combined (n = 117) and isolated choanal atresia cases (those without additional unrelated major defects; n = 61) were examined. Odds ratios (ORs), both unadjusted (uORs) and adjusted (aORs) for potential confounders, and 95% confidence intervals (CIs) were estimated using unconditional logistic regression analysis. For all choanal atresia cases combined, positive associations were observed with maternal pre-pregnancy intake in the highest quartile for vitamin B-12 (aOR = 1.9; CI = 1.1,3.1), zinc (aOR = 1.7; CI = 1.0,3.1), and niacin (aOR = 1.8; CI = 1.0,3.1), and intake in the lowest quartile for methionine (aOR = 1.6; CI = 1.0,2.6) and vitamin D (aOR = 1.6; CI = 1.0,2.4) compared to intake in the two intermediate quartiles combined. Further, a positive association was observed with periconceptional use of thyroid medications (uOR = 2.6; CI = 1.0,6.3) compared to no use of such medications. Among isolated choanal atresia cases, negative associations were observed for pantothenic acid (aOR = 0.4; CI = 0.2,0.9) and fat (aOR = 0.5; 95% CI = 0.2,1.0) intake in the lowest quartile compared to that in the intermediate quartiles, and positive associations were observed for periconceptional cigarette smoking (aOR = 2.3; CI = 1.1,4.7) compared to no smoking and pre-pregnancy daily coffee intake of 3 or more cups (aOR = 2.5; CI = 1.1,5.6) compared to intake of less than 1 cup per day. The positive association for periconceptional exposure to thyroid medications also persisted for isolated choanal atresia cases (uOR = 4.0; CI = 1.1,11.2). Because of the large number of associations tested, these findings may be due to chance. Alternatively, they may contribute new hypotheses regarding the etiology of choanal atresia; thus, requiring replication in additional studies.

Maternal residential atrazine exposure and risk for choanal atresia and stenosis in offspring

OBJECTIVE

To assess the relationship between estimated residential maternal exposure to atrazine during pregnancy and the risk for choanal atresia or stenosis in offspring.

STUDY DESIGN

Data for 280 nonsyndromic cases and randomly selected, population-based controls delivered between 1999 and 2008 were obtained from the Texas Birth Defects Registry. County-level estimates of atrazine levels obtained from the US Geological Survey were assigned to cases and controls based on maternal county of residence at delivery. Unconditional logistic regression was used to assess the relationship between maternal residential atrazine exposure and the risk for choanal atresia or stenosis in offspring.

RESULTS

Compared with offspring of mothers with low levels of estimated residential atrazine exposure, those with high levels had nearly a 2-fold increase in risk for choanal atresia or stenosis (aOR, 1.79; 95% CI, 1.17-2.74). A significant linear trend was also observed with increasing levels of atrazine exposure (adjusted P = .002).

CONCLUSION

A link between maternal exposure to endocrine disruptors, such as atrazine, and the risk of choanal atresia is plausible based on previous findings. Our results lend further support to this hypothesis.

Force-induced craniosynostosis via paracrine signaling in the murine sagittal suture

INTRODUCTION

The role of genetic phenomena has been given central importance in the development of craniosynostosis. Proponents have dismissed the role of force as a key etiologic factor. Nonetheless, compressive forces on the developing calvarium have been shown to result in premature suture fusion. The purpose of this study was to determine whether cyclical loading of the murine calvarium could induce suture fusion in cocultured calvarial specimens.

MATERIALS AND METHODS

Calvarial coupons from postnatal day 21, B6CBA wild-type mice (n = 24) were harvested and cultured. A custom appliance capable of delivering compressive loads was applied perpendicular to the sagittal suture in vitro. Six coupons were subjected to 0.3 g of force for 30 minutes each day for a total of 14 days. Six additional coupons were cocultured within the same medium. Control groups were devised. Histologic analysis of suture phenotype was performed.

RESULTS

Sagittal sutures cocultured with unloaded specimens remained patent. In contradistinction, 4 of 6 specimens cocultured with loaded coupons demonstrated craniosynostosis (P = 0.03). Increased osteoid, alkaline phosphatase staining, and bone sialoprotein expression were observed when compared with matched controls.

DISCUSSION

An in vitro model of force-induced craniosynostosis via paracrine effects has been devised. Premature fusion of the murine sagittal suture was induced in unloaded specimens cocultured with cyclically loaded calvarial coupons. These results implicate that abnormal forces may act through soluble factors to cause premature suture fusion in vitro. The findings support our global hypothesis that epigenetic phenomena play a crucial role in the pathogenesis of nonsyndromic craniosynostosis.

Fasciculation and guidance of spinal motor axons in the absence of FGFR2 signaling

During development, fibroblast growth factors (FGF) are essential for early patterning events along the anterior-posterior axis, conferring positional identity to spinal motor neurons by activation of different Hox codes. In the periphery, signaling through one of four fibroblast growth factor receptors supports the development of the skeleton, as well as induction and maintenance of extremities. In previous studies, FGF receptor 2 (FGFR2) was found to interact with axon bound molecules involved in axon fasciculation and extension, thus rendering this receptor an interesting candidate for the promotion of proper peripheral innervation. However, while the involvement of FGFR2 in limb bud induction has been extensively studied, its role during axon elongation and formation of distinct nervous projections has not been addressed so far. We show here that motor neurons in the spinal cord express FGFR2 and other family members during the establishment of motor connections to the forelimb and axial musculature. Employing a conditional genetic approach to selectively ablate FGFR2 from motor neurons we found that the patterning of motor columns and the expression patterns of other FGF receptors and Sema3A in the motor columns of mutant embryos are not altered. In the absence of FGFR2 signaling, pathfinding of motor axons is intact, and also fasciculation, distal advancement of motor nerves and gross morphology and positioning of axonal projections are not altered. Our findings therefore show that FGFR2 is not required cell-autonomously in motor neurons during the formation of initial motor projections towards limb and axial musculature.

Unique sex-based approach identifies transcriptomic biomarkers associated with non-syndromic craniosynostosis

BACKGROUND

The premature fusion of one cranial suture, also referred to as non-syndromic craniosynostosis, most commonly involves premature fusion of the sagittal, coronal, or metopic sutures, in that order. Population-based epidemiological studies have found that the birth prevalence of single-suture craniosynostosis is both suture- and sex-dependent.

METHODS

Transcriptomic data from 199 individuals with isolated sagittal (n = 100), unilateral coronal (n = 50), and metopic (n = 49) synostosis were compared against a control population (n = 50) to identify transcripts accounting for the different sex-based frequencies observed in this disease.

RESULTS

Differential sex-based gene expression was classified as either gained (divergent) or lost (convergent) in affected individuals to identify transcripts related to disease predilection. Divergent expression was dependent on synostosis sub-type, and was extensive in metopic craniosynostosis specifically. Convergent microarray-based expression was independent of synostosis sub-type, with convergent expression of FBN2, IGF2BP3, PDE1C and TINAGL1 being the most robust across all synostosis sub-types.

CONCLUSIONS

Analysis of sex-based gene expression followed by validation by qRT-PCR identified that concurrent upregulation of FBN2 and IGF2BP3, and downregulation of TINAGL1 in craniosynostosis cases were all associated with increased RUNX2 expression and may represent a transcriptomic signature that can be used to characterize a subset of single-suture craniosynostosis cases.

Genetic basis of potential therapeutic strategies for craniosynostosis

Craniosynostosis, the premature fusion of one or more cranial sutures, is a common malformation of the skull that can result in facial deformity and increased intracranial pressure. Syndromic craniosynostosis is present in ∼15% of craniosynostosis patients and often is clinically diagnosed by neurocranial phenotype as well as various other skeletal abnormalities. The most common genetic mutations identified in syndromic craniosynostosis involve the fibroblast growth factor receptor (FGFR) family with other mutations occurring in genes for transcription factors TWIST, MSX2, and GLI3, and other proteins EFNB1, RAB23, RECQL4, and POR, presumed to be involved either upstream or downstream of the FGFR signaling pathway. Both syndromic and nonsyndromic craniosynostosis patients require early diagnosis and intervention. The premature suture fusion can impose pressure on the growing brain and cause continued abnormal postnatal craniofacial development. Currently, treatment options for craniosynostosis are almost exclusively surgical. Serious complications can occur in infants requiring either open or endoscopic repair and therefore the development of nonsurgical techniques is highly desirable although arguably difficult to design and implement. Genetic studies of aberrant signaling caused by mutations underlying craniosynostosis in in vitro calvarial culture and in vivo animal model systems have provided promising targets in designing genetic and pharmacologic strategies for systemic or adjuvant nonsurgical treatment. Here we will review the current literature and provide insights to future possibilities and limitations of therapeutic applications.

Choanal atresia: current concepts and controversies

PURPOSE OF REVIEW

Choanal atresia is a common and widely recognized craniofacial disorder characterized by obliteration of the posterior nasal aperture. Given the long time since its original description, controversy persists regarding pathogenesis and optimal surgical techniques. This review addresses current literature on choanal atresia and identifies areas of debate and future opportunities in research.

RECENT FINDINGS

Recent molecular mechanisms in retinoic acid receptor development have been described in the pathogenesis of choanal atresia. Whereas surgical treatment is generally believed to be effective in alleviating respiratory symptoms, consistent data confirming efficacy are scarce regarding best surgical approach with and without endoscopic sinus techniques, adjuvant use of stents, use of antiproliferative agents and laser-assisted surgery. Recent studies regarding each technique are discussed.

SUMMARY

Despite vigorous research, the pathogenesis remains elusive and unproven. Many surgical techniques have been advocated; however, there is no dominant approach. Trends in treatment are directed towards the use of highly advanced endoscopic approaches with the use of microdebriders, small drill bits and telescopes to minimize traumatic injury that leads to postoperative scarring and restenosis.

Force-induced craniosynostosis in the murine sagittal suture

BACKGROUND

The cause of nonsyndromic craniosynostosis remains elusive. Although compressive forces have been implicated in premature suture fusion, conclusive evidence of force-induced craniosynostosis is lacking. The purpose of this study was to determine whether cyclical loading of the murine calvaria could induce suture fusion.

METHODS

Calvarial coupons from postnatal day-21, B6CBA, wild-type mice (n = 18) were harvested and cultured. A custom appliance capable of delivering controlled, cyclical, compressive loads was applied perpendicular to the sagittal suture within the coupon in vitro. Nine coupons were subjected to 0.3 g of force for 30 minutes each day for a total of 14 days. A control group of nine coupons was clamped in the appliance without loading. Analysis of suture phenotype was performed using alkaline phosphatase and hematoxylin and eosin staining techniques and in situ hybridization analysis using bone sialoprotein.

RESULTS

Control group sagittal sutures-which normally remain patent in mice-showed their customary histologic appearance. In contradistinction, sagittal sutures subjected to cyclic loading showed histologic evidence of premature fusion (craniosynostosis). In addition, alkaline phosphatase activity and bone sialoprotein expression were observed to be increased in the experimental group when compared with matched controls.

CONCLUSIONS

An in vitro model of force-induced craniosynostosis has been devised. Premature fusion of the murine sagittal suture was induced with the application of controlled, cyclical, compressive loads. These results implicate abnormal forces in the development of nonsyndromic craniosynostosis, which supports our global hypothesis that epigenetic phenomena play a crucial role in the pathogenesis of craniosynostosis.

Fibroblast growth factor 2-induced cytoplasmic asparaginyl-tRNA synthetase promotes survival of osteoblasts by regulating anti-apoptotic PI3K/Akt signaling

Fibroblast growth factor 2 (FGF2), the potent bone anabolic agent, regulates the bone development, as well as the growth, remodeling and healing of the fracture. The intracellular signaling of FGF2 leads to activation of genes involved in cell proliferation, migration, differentiation and survival. However, little is known about FGF2-regulated proteins in the osteoblasts. Therefore, in this study, protein profiling in FGF2-treated MC3T3-E1 preosteoblast cells was evaluated using proteomic technologies. Six proteins including asparaginyl-tRNA synthetase (NARS), eukaryotic translation termination factor 1 (ETF1), GDP-forming succinyl-CoA synthetase (SUCLG2), heat shock protein 84 (HSP 84), sorting nexin 9 (SNX9) and alpha glucosidase 2alpha neutral subunit (GANAB) were increased more than 3-fold after the FGF2 treatment. Also, two proteins including beta-tropomyosin and tropomyosin 2 were decreased to 2-folds. Among these proteins, asparaginyl-tRNA synthetase (NARS), a member of aminoacyl-tRNA synthetases (AARS), was strikingly up-regulated more than 900-fold. The overexpression of NARS significantly increased the proliferation of both the MC3T3-E1 and the primary mouse calvarial cells. In contrast, significant reduction of the basal expression of NARS by siNARS remarkably suppressed the proliferation and induced the death of cell. After the siNARS treatment, the resistance to apoptosis induced by serum deprivation was also significantly reduced. The level of p-Akt was also reduced and the activity of caspase 3 significantly enhanced. In addition, NARS-induced protection against apoptosis was abolished by the treatment of PI3K inhibitors, wortmannin and LY294002. In conclusion, we suggest that NARS is one of the important mediators of FGF2 induced survival signaling in osteoblasts through the activation of PI3K/Akt survival pathway.

Neurosurgical implications of achondroplasia

OBJECT

Achondroplasia is the most common form of human short-limbed dwarfism. The pediatric neurosurgeon is frequently required to treat children with achondroplasia who have hydrocephalus, cervicomedullary compression (CMD), and spinal canal stenosis. Accordingly, the authors have reviewed the experience of neurosurgery in children with achondroplasia at The Hospital for Sick Children.

METHODS

The medical records and neurosurgery database at The Hospital for Sick Children were searched to identify all children with achondroplasia who underwent at least 1 neurosurgical procedure between 1956 and the present.

RESULTS

Twenty-nine children with achondroplasia underwent 85 surgical procedures: 52 for CSF diversion in 12 patients, 20 for CMD in 18 patients, 8 for spinal disorders in 4 patients, and 5 for miscellaneous purposes in 4 patients. The CSF shunts were placed almost exclusively before 1990 and were associated with a significant number of complications. Patients undergoing CMD did very well, with only 1 patient failing to improve clinically.

CONCLUSIONS

This review provides a historical perspective on the evolution of treatment of pediatric patients with achondroplasia. The use of CSF diversion procedures, formerly fraught with complications, is now rare following the realization of the natural history of CSF space enlargement in these patients. Cervicomedullary compression is more commonly recognized due to better imaging. Central apnea is now better detected by routine sleep studies. Spine surgery, although rare, requires evaluation of both spinal stenosis and instability. These patients are best evaluated by a multidisciplinary team.

A young patient with polyarthralgia and hearing loss: a case report of Muenke syndrome

There are few reports of the typical radiographic findings in the hands and feet of patients with Muenke syndrome. We present a case report of a young girl with Muenke syndrome, whose diagnosis was made following the observation of coalitions and coned epiphyses on hand radiographs.

Tensile strain-induced Ets-2 phosphorylation by CaMKII and the homeostasis of cranial sutures

BACKGROUND

Mechanotransduction underpins the homeostasis of musculoskeletal tissues, including cranial sutures. Intracellular calcium, [Ca 2+]ic, and protein phosphorylation are two intermediate variables in signal relay during mechanotransduction. This project establishes a chain of cause and effect, linking cellular strain to substrate phosphorylation, and identifies the agent and target sites of phosphorylation.

METHODS

Cyclic tensile force (0.5 N at 1 Hz) was applied to 1-day-old rat sagittal sutures. [Ca 2+]ic was measured by FURA-2. Ets-2 phosphorylation by CaMKII was tested using Western blot autoradiography. Peptide array was constructed to determine the precise sites of phosphorylation. The results were confirmed with mass spectroscopy and Western blots using phospho-specific antibodies.

RESULTS

[Ca 2+]ic increased rapidly in response to tensile stress. In the presence of Ca2+, CaMKII caused Ets-2 phosphorylation. Of the three possible sites for phosphorylation of Ets-2 by CaMKII, RVPS, FESF, RLSS, Serine 246, 310, and 313 were the targets. Furthermore, the contiguous sequence modified this effect. Mass spectroscopy showed 80 Da (molecular weight of phosphate group, -PO3) right shifts consistent with phosphorylation. There was cytosolic translocation of Ets-2 on tensile deformation of suture cells. CaMKII binding of Ets-2 occurred within 30 minutes after the onset of tensile strain.

CONCLUSIONS

Cranial suture cells can respond to tensile forces by increasing [Ca 2+]ic, which causes CaMKII to phosphorylate Ets-2, thus altering Ets-2 binding to its downstream promoters. Of note, Ets-2 is at the intersection of three key pathways important in craniosynostosis: fibroblast growth factor-2, transforming growth factor-beta, and mechanotransduction.

A Pro253Arg mutation in fibroblast growth factor receptor 2 (Fgfr2) causes skeleton malformation mimicking human Apert syndrome by affecting both chondrogenesis and osteogenesis

Apert syndrome is one of the most severe craniosynostosis that is mainly caused by either a Ser252Trp(S252W) or Pro253Arg(P253R) mutation in fibroblast growth factor receptor 2 (FGFR2). As an autosomal dominant disorder, Apert syndrome is mainly characterized by skull malformation resulting from premature fusion of craniofacial sutures, as well as syndactyly, etc. A P253R mutation of FGFR2 results in nearly one-thirds of the cases of Apert syndrome. The pathogenesis of Apert syndrome resulting from P253R mutation of FGFR2 is still not fully understood. Here we reported a knock-in mouse model carrying P253R mutation in Fgfr2. The mutant mice exhibit smaller body size and brachycephaly. Analysis of the mutant skulls and long bones revealed premature fusion of coronal suture, shortened cranial base and growth plates of long bones. In vitro organ culture studies further revealed that, compared with wild-type littermates, the mutant mice have prematurely fused coronal sutures and retarded long bone growth. Treatment of the cultured calvaria and femur with PD98059, an Erk1/2 inhibitor, resulted in partially alleviated coronal suture fusion and growth retardation of femur respectively. Our data indicated that the P253R mutation in Fgfr2 directly affect intramembranous and endochondral ossification, which resulted in the premature closure of coronal sutures and growth retardation of long bones and cranial base. And the Erk1/2 signaling pathway partially mediated the effects of P253R mutation of Fgfr2 on cranial sutures and long bones.

Endocardial cushion defect in a patient with Crouzon syndrome carrying a mutation in the fibroblast growth factor receptor (FGFR)-2 gene

Crouzon syndrome is an autosomal dominant disorder caused by mutation in the fibroblast growth factor receptor (FGFR)-2 gene. Recent findings from animal studies imply a critical role for FGFs in the regulation of cardiac development including cardiac cushion proliferation and valvulogenesis. We report on a 36-year-old woman, who required surgical closure for an atrial septal defect, a clinical feature that has not been previously reported in other patients with Crouzon syndrome. The findings suggest that cardiac investigations are warranted in patients with a diagnosis of Crouzon syndrome.

Achondroplasia

Achondroplasia is the most common form of short limb dwarfism in human beings, affecting more than 250,000 individuals worldwide. More than 95% of patients have the same point mutation in the gene for fibroblast growth factor receptor 3 (FGFR3) and more than 80% of these are new mutations. The mutation, which causes gain of FGFR3 function, affects many tissues, most strikingly the cartilaginous growth plate in the growing skeleton, leading to a variety of manifestations and complications. The biology of FGFR3 and the molecular and cellular consequences of the achondroplasia mutation are being elucidated, providing a more complete understanding of the disorder and a basis for future treatments targeted directly at relevant pathogenetic pathways. Furthermore, the natural history of the condition, which has been well delineated in childhood and adolescence, is being defined more fully in adults with achondroplasia; most of the serious complications can be modified favourably or prevented by anticipation and early treatment. Possible future treatments include chemical inhibition of receptor signalling, antibody blockade of receptor activation, and alteration of pathways that modulate the downstream propagation of FGFR3 signals.

The C. elegans Twist target gene, arg-1, is regulated by distinct E box promoter elements

Proper metazoan mesoderm development requires the function of a basic helix-loop-helix (bHLH) transcription factor, Twist. Twist-containing dimers regulate the expression of target genes by binding to E box promoter elements containing the site CANNTG. In Caenorhabditis elegans, CeTwist functions in a subset of mesodermal cells. Our study focuses on how CeTwist controls the expression of its target gene, arg-1. We find that a 385bp promoter region of arg-1, which contains three different E box elements, is sufficient for maintaining the full CeTwist-dependent expression pattern. Interestingly, the expression of arg-1 in different tissues is regulated distinctly, and each of the three E boxes plays a unique role in the regulation. The first and the third E boxes (E1 and E3) are required for expression in a distinct subset of the mesodermal tissues where arg-1 is normally expressed, and the second E box (E2) is required for expression in the full set of those tissues. The essential role of E2 in arg-1 regulation is correlated with the finding that E2 binds with greater affinity than E1 or E3 to CeTwist dimers. A potential role for additional transcription factors in mesodermal gene regulation is suggested by the discovery of a novel site that is also required for arg-1 expression in a subset of the tissues but is not bound in vitro by CeTwist. On the basis of these results, we propose a model of CeTwist gene regulation in which expression is controlled by tissue-specific binding of distinct sets of E boxes.

Attenuation of signaling pathways stimulated by pathologically activated FGF-receptor 2 mutants prevents craniosynostosis

Craniosynostosis, the fusion of one or more of the sutures of the skull vault before the brain completes its growth, is a common (1 in 2,500 births) craniofacial abnormality, approximately 20% of which occurrences are caused by gain-of-function mutations in FGF receptors (FGFRs). We describe a genetic and pharmacological approach for the treatment of a murine model system of Crouzon-like craniosynostosis induced by a dominant mutation in Fgfr2c. Using genetically modified mice, we demonstrate that premature fusion of sutures mediated by Crouzon-like activated Fgfr2c mutant is prevented by attenuation of signaling pathways by selective uncoupling between the docking protein Frs2alpha and activated Fgfr2c, resulting in normal skull development. We also demonstrate that attenuation of Fgfr signaling in a calvaria organ culture with an Fgfr inhibitor prevents premature fusion of sutures without adversely affecting calvaria development. These experiments show that attenuation of FGFR signaling by pharmacological intervention could be applied for the treatment of craniosynostosis or other severe bone disorders caused by mutations in FGFRs that currently have no treatment.

Palpatory diagnosis of plagiocephaly

INTRODUCTION

The term plagiocephaly, from the Greek plagios (oblique) and kephalê (head), means distortion of the head, and refers clinically to cranial asymmetry. Cranial Osteopathy, since it was first proposed, has focussed upon the diagnosis and treatment of birth trauma and cranial asymmetries, and consequently specific therapy for plagiocephalic deformities has been described. Osteopathic manipulation also has been proposed as a treatment for torticollis, a condition associated with plagiocephaly. For these reasons, we decided to look at the mechanics of the occipital bone and the adjacent atlas and bones of the cranial base, in relation to functional plagiocephaly.

METHODS

The records of 649 children seen in an osteopathic practice in Lyon, France, were reviewed retrospectively, in compliance with the legal requirements of the Commission Nationale de l'Informatique et des Libertés (CRIL) and the Helsinki accord, for gender, age at presentation, birth history, obstetrical data (breech presentation, vacuum extraction, forceps delivery or Caesarean section), presenting complaint, side of posterior plagiocephaly, side of frontal plagiocephaly, torticollis, motion pattern of the occipital bone upon the atlas, and motion pattern of the spheno-occipital synchondrosis.

RESULTS

We found significant correlations between plagiocephaly (right/left) and primipara (P=0.024), use of forceps (P=0.055) and extractor suction (P=0.055). Correlations were also found between flattening of the occiput (right/left) and lateral strain of the spheno-occipital synchondrosis (P=0.002) and between plagiocephaly (right/left) and occipito-atlantal motion (P=0.000).

CONCLUSION

We found a significant correlation between the lateral strain pattern of the spheno-occipital synchondrosis and plagiocephaly and between rotational dysfunction of the occiput upon the atlas and the side of posterior plagiocephaly. We suggest that thorough neonatal osteopathic examination can identify individuals predisposed to develop posterior plagiocephaly.

Identification of novel target genes of CeTwist and CeE/DA

Twist, a basic helix-loop-helix (bHLH) transcription factor, plays an important role in mesoderm development in many organisms, including C. elegans where CeTwist is required to direct cell fate specifications of a subset of mesodermal cells. Although several target genes of CeTwist have been identified, how this protein accomplishes its function is unclear. In addition, several human genes whose mutations cause different syndromes of craniosynostosis (premature fusion of cranial sutures) have homologues in the CeTwist pathway. Identification of novel target genes of CeTwist will shed more light on the functions of CeTwist in mesoderm development, and the corresponding human homologues will be good candidates for related syndromes with unidentified mutated genes. In our study, both CeTwist and its heterodimeric partner, CeE/DA, were overexpressed from the inducible heat-shock promoter, and potential target genes were detected with Affymetrix oligonucleotide microarrays. Using transcriptional GFP reporters, we found 11 genes were expressed in cells coincident with known CeTwist target gene products. Based on subsequent validation experiments, 9 genes were defined as novel CeTwist and CeE/DA targets. Human homologues of two of these genes might be involved in craniofacial diseases, which further validates C. elegans as a good model organism for providing insights into these disorders.

Apert syndrome: what prenatal radiographic findings should prompt its consideration?

Apert syndrome was diagnosed in a newborn with typical facial and digital features whose only detected prenatal abnormality had been agenesis of the corpus callosum. This prompted a review of the central nervous system findings in all cases of Apert syndrome treated at the Craniofacial Center Boston Children's Hospital between 1978 and 2004. Two of 30 patients with Apert syndrome had prenatal identification of mild dilatation of the lateral cerebral ventricles and complete agenesis of the corpus callosum (ACC) documented with both ultrasound and MRI. Both had the common S252W mutation of FGFR2. Though cranial and orbital malformations typical of Apert were eventually seen in these fetuses in the third-trimester, even in retrospect, these were not detectable at mid second-trimester, ultrasound screening for congenital malformations. Hand malformations also went undetected in the second-trimester despite extensive imaging by experienced radiologists. We conclude that prenatal ultrasonographic identification of mild ventriculomegaly or ACC should stimulate a careful search for features of Apert syndrome and prompt follow-up imaging to look for bony abnormalities that have later onset. Prenatal molecular testing for Apert mutations should be considered in cases of mild ventriculomegaly and ACC.

Loss-of-function mutation of the AF9/MLLT3 gene in a girl with neuromotor development delay, cerebellar ataxia, and epilepsy

The human AF9/MLLT3 gene is a common fusion partner for the MLL gene in translocations t(9;11)(p22;q23) associated with acute myeloid leukemia and acute lymphocytic leukemia. The exact function of the gene is still unknown, although a mouse knock-out model points to a role as a controller of embryo patterning. We report the case of a constitutional translocation t(4;9)(q35;p22) disrupting the AF9/MLLT3 gene in a girl with neuromotor development delay, cerebellar ataxia and epilepsy. Array-CGH analysis at 1 Mbase resolution did not reveal any additional deletions/duplications. We hypothesize a loss-of-function mutation of the AF9/MLLT3 gene, and a possible role for the FAT gene on chromosome 4, in the genesis of the proband's severe neurological phenotype.

The Bowstring Canthal Advancement: A New Technique to Correct the Flattened Supraorbital Rim in Unilateral Coronal Synostosis

Patients with unilateral coronal synostosis characteristically have a recessed and flattened supraorbital rim ipsilateral to the fused suture. Despite lateral canthal advancement procedures to correct these anomalies, patients often have a persistent flattened and recessed supraorbital rim after surgery. Current procedures address the pathologic features of the orbital rim only partially by advancing forward a deformed supraorbital rim without correcting the abnormal flattening of the normal rim curvature. The authors describe a technique modification of the supraorbital rim advancement procedure that addresses not only the lack of anterior positioning of it, but also its flattened contour: the bowstring canthal advancement.

The Zebrafish (Danio rerio): A Model System for Cranial Suture Patterning

The zebrafish (Danio rerio) is an alluring model system currently used to study early embryonic development, organogenesis and gene functional analysis. However, few studies have been devoted to post-embryonic development. We have explored the possibility of using this organism to analyze how cranial suture patterning occurs. This study reports on the establishment of the zebrafish skull vault anatomy, calvarial osteogenesis, and cranial suture morphology. Our results demonstrate that the anatomy of the zebrafish cranial vault and cranial sutures is very similar to that of mammalian organisms. Indeed, the zebrafish represents a versatile and valuable model system for the study of the biogenesis of cranial sutures.

Muenke syndrome

BACKGROUND

Muenke syndrome is a genetically determined craniosynostosis that involves one or both coronal sutures. In some patients it is associated with skeletal abnormalities such as thimble-like middle phalanges, coned epiphysis, and/or neurological impairment, namely sensorineural hearing loss or mental retardation. In spite of a variable phenotype, Muenke syndrome has been related to a unique mutation on the FGFR3 gene, Pro 250 to Arg, which is characteristic of this disease. Because of the incomplete penetrance of this anomaly, the suspicion of Muenke syndrome must be raised in any child with uni- or bilateral coronal craniosynostosis, and the genetic analysis propounded even in the absence of extracranial features.

ILLUSTRATIVE CASES

We report the cases of two sisters who presented with Muenke syndrome and whose affected mother did not have any form of craniosynostosis.

Prenatal Diagnosis of Apert Syndrome

OBJECTIVE

The role of the human fibroblast growth factor receptor (FGFR) gene family in current prenatal diagnosis and management of craniosynostosis syndromes and skeletal dysplasias is discussed.

METHOD

We present the antenatal ultrasound findings, diagnosis, and management of 2 cases of Apert syndrome before and after molecular prenatal diagnosis was available.

RESULTS AND CONCLUSION

Discovery of mutations in FGFR genes now allows the definitive antenatal diagnosis of Apert syndrome, other craniosynostosis syndromes, and skeletal dysplasias.

Earliest mineral and matrix changes in force-induced musculoskeletal disease as revealed by Raman microspectroscopic imaging

Craniosynostosis, premature fusion of the skull bones at the sutures, is the second most common human birth defect in the skull. Raman microspectroscopy was used to examine the composition, relative amounts, and locations of the mineral and matrix produced in mouse skulls undergoing force-induced craniosynostosis. Raman imaging revealed decreased relative mineral content in skulls undergoing craniosynostosis compared with unloaded specimens.

INTRODUCTION

Raman microspectroscopy, a nondestructive vibrational spectroscopic technique, was used to examine the composition, relative amounts, and locations of the mineral and matrix produced in mouse skulls undergoing force-induced craniosynostosis. Craniosynostosis, premature fusion of the skull bones at the sutures, is the second most common birth defect in the face and skull. The calvaria, or flat bones that comprise the top of the skull, are most often affected, and craniosynostosis is a feature of over 100 human syndromes and conditions.

MATERIALS AND METHODS

Raman images of the suture, the tips immediately adjacent to the suture (osteogenic fronts), and mature parietal bones of loaded and unloaded calvaria were acquired. Images were acquired at 2.6 x 2.6 microm spatial resolution and ranged in a field of view from 180 x 210 microm to 180 x 325 microm.

RESULTS AND CONCLUSIONS

This study found that osteogenic fronts subjected to uniaxial compression had decreased relative mineral content compared with unloaded osteogenic fronts, presumably because of new and incomplete mineral deposition. Increased matrix production in osteogenic fronts undergoing craniosynostosis was observed. Understanding how force affects the composition, relative amounts, and location of the mineral and matrix provides insight into musculoskeletal disease in general and craniosynostosis in particular. This is the first report in which Raman microspectroscopy was used to study musculoskeletal disease. These data show how Raman microspectroscopy can be used to study subtle changes that occur in disease.

Demonstration of cranial sutures and fontanelles at 15 to 16 weeks of gestation: a comparison between two-dimensional and three-dimensional ultrasonography

OBJECTIVE

The purpose of this study was to evaluate the feasibility of obtaining good quality three-dimensional ultrasound pictures of the cranial sutures and fontanelles and to compare between two-dimensional and three-dimensional ultrasound in identifying the normal appearance of cranial sutures and fontanelles by the transvaginal approach at 15 to 16 weeks of gestation.

METHODS

Fifty fetuses were prospectively evaluated by two-dimensional and three-dimensional transvaginal sonography between 15 and 16 weeks of gestation. The sagittal, coronal, lambdoidal, and metopic sutures, as well as anterior and posterior fontanelles, were inspected.

RESULTS

Three-dimensional ultrasound enabled visualization of all sutures in 37 (74%) fetuses compared to 28 (56%) fetuses examined by two-dimensional ultrasonography (p = NS). The visualization of the sagittal suture was significantly superior by three-dimensional ultrasonography compared to two-dimensional ultrasonography (50 (100%) vs 35 (70%), p < 0.001). No significant difference between the two modalities was found in visualization of the fontanelles.

CONCLUSION

Sutures and fontanelles are usually satisfactorily demonstrated by two-dimensional and three-dimensional ultrasound at 15 to 16 weeks of gestation. The sagittal suture is difficult to visualize using two-dimensional ultrasound, and three-dimensional ultrasound appears to be the best method for its demonstration.