A clinical study of the craniofacial features in Apert syndrome

Facial growth in patients with apert and crouzon syndromes compared to normal children

OBJECTIVE

To evaluate vertical and sagittal facial growth in children with Apert and Crouzon syndromes and compare it to the growth patterns of a nonsyndromic control group.

DESIGN

Case-control study.

SETTING

Department of Orthodontics, Children's Hospital Erasmus Medical Centre, Sophia, Rotterdam, The Netherlands.

PATIENTS, PARTICIPANTS

Sixty-two patients (37 patients with Crouzon syndrome and 25 patients with Apert syndrome) born between 1971 and 2001 (age range 3.9 to 32 years) and 482 nonsyndromic children as a control group.

INTERVENTIONS

Lateral cephalograms performed prior to any midfacial surgery of 62 patients and 482 nonsyndromic children were traced and horizontal and vertical measurements were digitized.

MAIN OUTCOME MEASURES

Cephalometric measurements of SNA, SNB, ANB, NSMe, and SN/palatal plane angles and lower facial height ratio.

RESULTS

Horizontal measurements for the syndromic groups showed no change in SNA angle during growth. SNA angles were lower in patients with Apert syndrome compared to patients with Crouzon syndrome. The syndromic groups showed smaller values for ANB angles compared to the nonsyndromic group. Vertical measurements showed increased lower facial height ratios for the syndromic groups compared to control subjects. There was an increasing counterclockwise rotation of the palatal plane in relation to the anterior cranial base in syndromic patients. NSMe angles among the three groups were not significantly different.

CONCLUSIONS

Based on the growth differences identified, the sagittal and vertical jaw relationships differ in patients with Crouzon syndrome, patients with Apert syndrome, and control subjects. Syndromic patients show aggravation of midfacial underdevelopment and anterior rotation of the mandible.

Beyond the closed suture in apert syndrome mouse models: evidence of primary effects of FGFR2 signaling on facial shape at birth

Apert syndrome is a congenital disorder caused mainly by two neighboring mutations on fibroblast growth factor receptor 2 (FGFR2). Premature closure of the coronal suture is commonly considered the identifying and primary defect triggering or preceding the additional cranial malformations of Apert phenotype. Here we use two transgenic mouse models of Apert syndrome, Fgfr2(+/S252W) and Fgfr2(+/P253R), to explore variation in cranial phenotypes in newborn (P0) mice. Results show that the facial skeleton is the most affected region of the cranium. Coronal suture patency shows marked variation that is not strongly correlated with skull dysmorphology. The craniofacial effects of the FGFR2 mutations are similar, but Fgfr2(+/S252W) mutant mice display significantly more severe dysmorphology localized to the posterior palate. Our results demonstrate that coronal suture closure is neither the primary nor the sole locus of skull dysmorphology in these mouse models for Apert syndrome, but that the face is also primarily affected.

Dynamic morphological changes in the skulls of mice mimicking human Apert syndrome resulting from gain-of-function mutation of FGFR2 (P253R)

Apert syndrome is caused mainly by gain-of-function mutations of fibroblast growth factor receptor 2. We have generated a mouse model (Fgfr2(+/P253R)) mimicking human Apert syndrome resulting from fibroblast growth factor receptor 2 Pro253Arg mutation using the knock-in approach. This mouse model in general has the characteristic skull morphology similar to that in humans with Apert syndrome. To characterize the detailed changes of form in the overall skull and its major anatomic structures, euclidean distance matrix analysis was used to quantitatively compare the form and growth difference between the skulls of mutants and their wild-type controls. There were substantial morphological differences between the skulls of mutants and their controls at 4 and 8 weeks of age (P < 0.01). The mutants showed shortened skull dimensions along the rostrocaudal axis, especially in their face. The width of the frontal bone and the distance between the two orbits were broadened mediolaterally. The neurocrania were significantly increased along the dorsoventral axis and slightly increased along the mediolateral axis, and also had anteriorly displayed opisthion along the rostrocaudal axis. Compared with wild-type, the mutant mandible had an anteriorly displaced coronoid process and mandibular condyle along the rostrocaudal axis. We further found that there was catch-up growth in the nasal bone, maxilla, zygomatic bone and some regions of the mandible of the mutant skulls during the 4-8-week interval. The above-mentioned findings further validate the Fgfr2(+/P253R) mouse strain as a good model for human Apert syndrome. The changes in form characterized in this study will help to elucidate the mechanisms through which the Pro253Arg mutation in fibroblast growth factor receptor 2 affects craniofacial development and causes Apert syndrome.

Sutural growth restriction and modern human facial evolution: an experimental study in a pig model

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper. The present analysis was designed to assess anteroposterior facial reduction in a pig model and to examine the potential role that this dynamic has played in the evolution of modern human facial form. Ten female sibship cohorts, each consisting of three individuals, were allocated to one of three groups. In the experimental group (n = 10), microplates were affixed bilaterally across the zygomaticomaxillary and frontonasomaxillary sutures at 2 months of age. The sham group (n = 10) received only screw implantation and the controls (n = 10) underwent no surgery. Following 4 months of post-surgical growth, we assessed variation in facial form using linear measurements and principal components analysis of Procrustes scaled landmarks. There were no differences between the control and sham groups; however, the experimental group exhibited a highly significant reduction in facial projection and overall size. These changes were associated with significant differences in the infraorbital region of the experimental group including the presence of an infraorbital depression and an inferiorly and coronally oriented infraorbital plane in contrast to a flat, superiorly and sagittally infraorbital plane in the control and sham groups. These altered configurations are markedly similar to important additional facial features that differentiate modern humans from archaic Homo, and suggest that facial length restriction via rigid plate fixation is a potentially useful model to assess the developmental factors that underlie changing patterns in craniofacial form associated with the emergence of modern humans.

Dysphagia and nutrition problems in infants with apert syndrome

OBJECTIVE

The purpose of this study was to identify and describe the nature of dysphagia and nutrition difficulties in infants with Apert syndrome.

DESIGN

The study comprised a review of the medical, nutrition, and feeding records of 13 consecutive infants still feeding by the bottle who had been referred to the Craniofacial Unit and analyses of swallow function from videofluoroscopic swallow investigations.

MAIN OUTCOME MEASURES

Outcome measures included qualitative analyses of bottle-feeding and nutritional status and quantitative functional severity ratings of dysphagia based on videofluoroscopic swallow investigations using the O'Neil et al. (1999) Dysphagia Outcome Severity Scale.

RESULTS

The main qualitative descriptors of oral feeding in this cohort included uncoordinated suck-swallow-breathe patterns, inability to maintain sucking bursts, and changes in respiratory patterns as the feed progressed. Videofluoroscopic evaluations (N = 7) showed silent laryngeal penetration or aspiration in more than half of the cohort. Failure to thrive was a frequent occurrence seen in seven infants, and 9 of the 10 required dietetic intervention and enteral supplements. (Nutritional records were not located for three infants.)

CONCLUSIONS

In view of the small sample size and retrospective nature of the study, the results need to be interpreted with caution. However, the study adds to current limited knowledge on feeding and nutrition in Apert syndrome. Further prospective multidisciplinary and objective research is clearly warranted.

Detecting an undiagnosed case of nonsyndromic facial dysmorphism using geometric morphometrics

The Johns Hopkins University Center for Craniofacial Development and Disorders estimates that 1 in 3,000 children born in the United States is diagnosed with a rare form of craniosynostosis. Although the medical literature has documented numerous descriptions of craniofacial disorders from an anthropometric or genetic perspective, considerably fewer reports of these anomalies have been documented in the context of forensic anthropology. Similar genetic origins of many craniofacial anomalies generate ranges of phenotypic variation between and even within documented cases, producing difficulties in acquiring correct diagnoses. Identical physical characteristics manifested in different disorders create further complications in identifying a craniofacial syndrome in skeletal remains. Reported here is an unusual case of a possibly undiagnosed craniofacial abnormality in a set of identified skeletal remains from a North Carolina homicide case. Traditional metric and geometric morphometric approaches were utilized to further investigate morphological shape differences between the case study and a reference sample. Results show significant differences suggesting a nonsyndromic form of craniosynostosis.

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.

Intraoral features of Apert’s syndrome

OBJECTIVE

To evaluate the intraoral features of patients with Apert's syndrome in treatment at the Hospital of Rehabilitation and Craniofacial Anomalies of University of São Paulo (HRAC-USP), a national reference center for treatment of craniofacial anomalies in Brazil.

STUDY DESIGN

In this retrospective study, of 56,000 patients registered at HRAC-USP, 36 patients were diagnosed with Apert's syndrome and were either examined or had their medical files evaluated, aiming to characterize lip posture, mouth shape, maxillary hypoplasia, palatal morphology, dental anomalies, and malocclusion.

RESULTS

Most patients were characterized as mouth breathers for presenting with hypotonic lips and trapezoidal-shaped mouths. Other frequent findings were the presence of highly arched palates and hypoplastic maxilla, with gingival lateral swellings that increased in size with age. Crowding of teeth and malocclusion were commonly observed, and cases of hypodontia were frequent. Contrary to previous studies demonstrating a high incidence of cleft soft palate, in this study only 1 of 23 patients presented a true cleft.

CONCLUSIONS

The intraoral features of patients with Apert's syndrome in the population studied match most of the findings in other populations. However, the occurrence of cleft soft palate was unexpectedly low and morphologically normal teeth were found. In addition, hypodontia was frequently observed. Variations in frequency of observations of some characteristics might be related to differences in sample size or population.

[Known gene interactions as implicated in craniofacial development]

Many genes intervening in development, morphogenesis and craniofacial growth have been identified, primarily by the use of mice mutants. We can distinguish two families: the signalling factors and the transcription factors. The latter interact with DNA to activate or to inhibit the expression of other genes. Some of the transcription factors are called homeogenes because they interact with DNA by a sequence of amino acids known as homeobox that has been carefully conserved throughout the course of evolution. Those factors interact, and signalling cascades have been described. Current research projects seek to discern the exact role of each of these genes in craniofacial growth and to develop a better understanding of the interactions between them.

The spectrum of Apert syndrome: phenotype, particularities in orthodontic treatment, and characteristics of orthognathic surgery

In the PubMed accessible literature, information on the characteristics of interdisciplinary orthodontic and surgical treatment of patients with Apert syndrome is rare. The aim of the present article is threefold: (1) to show the spectrum of the phenotype, in order (2) to elucidate the scope of hindrances to orthodontic treatment, and (3) to demonstrate the problems of surgery and interdisciplinary approach.

Children and adolescents who were born in 1985 or later, who were diagnosed with Apert syndrome, and who sought consultation or treatment at the Departments of Orthodontics or Craniomaxillofacial Surgery at the Dental School of the University Hospital of Münster (n = 22; 9 male, 13 female) were screened. Exemplarily, three of these patients (2 male, 1 female), seeking interdisciplinary (both orthodontic and surgical treatment) are presented. Orthodontic treatment before surgery was performed by one experienced orthodontist (AH), and orthognathic surgery was performed by one experienced surgeon (UJ), who diagnosed the syndrome according to the criteria listed in OMIM™.

In the sagittal plane, the patients suffered from a mild to a very severe Angle Class III malocclusion, which was sometimes compensated by the inclination of the lower incisors; in the vertical dimension from an open bite; and transversally from a single tooth in crossbite to a circular crossbite. All patients showed dentitio tarda, some impaction, partial eruption, idopathic root resorption, transposition or other aberrations in the position of the tooth germs, and severe crowding, with sometimes parallel molar tooth buds in each quarter of the upper jaw.

Because of the severity of malocclusion, orthodontic treatment needed to be performed with fixed appliances, and mainly with superelastic wires. The therapy was hampered with respect to positioning of bands and brackets because of incomplete tooth eruption, dense gingiva, and mucopolysaccharide ridges. Some teeth did not move, or moved insufficiently (especially with respect to rotations and torque) irrespective of surgical procedures or orthodontic mechanics and materials applied, and without prognostic factors indicating these problems. Establishing occlusal contact of all teeth was difficult. Tooth movement was generally retarded, increasing the duration of orthodontic treatment. Planning of extractions was different from that of patients without this syndrome.

In one patient, the sole surgical procedure after orthodontic treatment with fixed appliances in the maxilla and mandible was a genioplasty. Most patients needed two- jaw surgery (bilateral sagittal split osteotomy [BSSO] with mandibular setback and distraction in the maxilla). During the period of distraction, the orthodontist guided the maxilla into final position by means of bite planes and intermaxillary elastics.

To our knowledge, this is the first article in the PubMed accessible literature describing the problems with respect to interdisciplinary orthodontic and surgical procedures. Although the treatment results are not perfect, patients undergoing these procedures benefit esthetically to a high degree.

Patients need to be informed with respect to the different kinds of extractions that need to be performed, the increased treatment time, and the results, which may be reached using realistic expectations.

Ocular abnormalities in Apert syndrome: genotype/phenotype correlations with fibroblast growth factor receptor type 2 mutations

BACKGROUND/PURPOSE

Apert syndrome, a disorder of craniosynostosis, syndactyly, and other craniofacial malformations, is caused by point mutations (Ser252Trp or Pro253Arg) in the fibroblast growth factor receptor 2 gene. This study's goal was to determine ophthalmic phenotype/genotype correlations in patients with either mutation.

METHODS

A retrospective chart review of demographic and ophthalmologic data was performed for 18 children carrying either the S252W (11) or the P253R (7) mutation. Fisher exact tests were performed to determine significance of variable phenotypes between the two mutation groups.

RESULTS

In the P253R group, 85% had strabismus (14% required surgery), 71% had ptosis, 43% had amblyopia, 14% had nasolacrimal duct obstruction, 14% had myopia, 14% had hyperopia, and 14% had astigmatism. In the S252W group, 91% had strabismus (64% required surgery), 73% had ptosis, 73% had amblyopia, 100% had nasolacrimal duct obstruction, 36% had myopia, 9% had hyperopia, and 82% had astigmatism. Overall, S252W and P253R groups showed significantly different numbers of patients with strabismus requiring surgery (p = 0.039), superior rectus muscle underaction (p = 0.024), nasolacrimal duct obstruction (p = 0.0002), and astigmatism (p = 0.005).

CONCLUSIONS

Compared with patients with the P253R mutation, Apert syndrome patients with the S252W mutation may have more severe ocular phenotypes with a higher likelihood of developing strabismus, especially vertical deviation. They also are more likely to develop astigmatic refractive errors and tearing secondary to nasolacrimal system anomalies.

Ophthalmic findings in apert syndrome prior to craniofacial surgery

PURPOSE

To determine ophthalmic findings in patients with Apert syndrome before craniofacial surgery.

DESIGN

A cross-sectional retrospective study.

METHODS

Review of 63 cases (27 males, 36 females) with Apert syndrome without craniofacial surgery from the Australian Craniofacial Unit. Demographic data, age of presentation, and ophthalmic findings at the first presentation were recorded.

RESULTS

At a mean age of four years and median age of one year, at least 14% of patients had amblyopia, 60% of patients had strabismus, 19% of patients had anisometropia, and 34% of eyes had ametropia. Exposure keratopathy and corneal scarring occurred in at least 13% of patients and optic atrophy in at least 8% of patients.

CONCLUSIONS

This study demonstrated that patients with Apert syndrome were at risk of amblyopia because of high prevalence of refractive errors, strabismus, and anisometropia. Exposure keratopathy and corneal scarring occurred commonly.

Apert syndrome with glucose-6-phosphate dehydrogenase deficiency: a case report

Apert syndrome is characterized by midface hypoplasia, syndactyly of the hands and feet, proptosis of eyes, steep and flat frontal bones, and premature union of cranial sutures. Maxillary hypoplasia, deep palatal vault, anterior open bite, crowding of the dental arch, severely delayed tooth eruption, and dental malocclusion are the main oral manifestations of this syndrome. In this report, a case of Apert syndrome with glucose-6-phosphate dehydrogenase (G(6)PD) deficiency is presented. The patient, a 4-year-old male and the fourth child of healthy parents, was admitted to our department because of delayed tooth eruption. He had all the cardinal symptoms of the Apert syndrome. Clinical examination revealed that primary centrals, canines and first molars erupted; however, primary second molars and laterals had not erupted. The patient had no dental caries. Preventive treatments were applied, and subsequently, the patient was taken to long-term follow up.

Hush puppy: a new mouse mutant with pinna, ossicle, and inner ear defects

OBJECTIVES/HYPOTHESIS

Deafness can be associated with abnormalities of the pinna, ossicles, and cochlea. The authors studied a newly generated mouse mutant with pinna defects and asked whether these defects are associated with peripheral auditory or facial skeletal abnormalities, or both. Furthermore, the authors investigated where the mutation responsible for these defects was located in the mouse genome.

METHODS

The hearing of hush puppy mutants was assessed by Preyer reflex and electrophysiological measurement. The morphological features of their middle and inner ears were investigated by microdissection, paint-filling of the labyrinth, and scanning electron microscopy. Skeletal staining of skulls was performed to assess the craniofacial dimensions. Genome scanning was performed using microsatellite markers to localize the mutation to a chromosomal region.

RESULTS

Some hush puppy mutants showed early onset of hearing impairment. They had small, bat-like pinnae and normal malleus but abnormal incus and stapes. Some mutants had asymmetrical defects and showed reduced penetrance of the ear abnormalities. Paint-filling of newborns' inner ears revealed no morphological abnormality, although half of the mice studied were expected to carry the mutation. Reduced numbers of outer hair cells were demonstrated in mutants' cochlea on scanning electron microscopy. Skeletal staining showed that the mutants have significantly shorter snouts and mandibles. Genome scan revealed that the mutation lies on chromosome 8 between markers D8Mit58 and D8Mit289.

CONCLUSION

The study results indicate developmental problems of the first and second branchial arches and otocyst as a result of a single gene mutation. Similar defects are found in humans, and hush puppy provides a mouse model for investigation of such defects.

CT imaging of craniofacial malformations

Because of its superior depiction of bone detail, CT is a useful tool in the characterization of CF deformities and presurgical planning. Modern CT scanners and workstations provide 2D techniques such as multiplanar reformats and 3D techniques, such as MIP and volume renderings, which may be used effectively in the diagnosis and management of patients with CF malformations.

The dental health and caries-related microflora in children with craniosynostosis

OBJECTIVE

To compare levels of dental caries, bacterial dental plaque, gingivitis, enamel defects, and caries-related microflora in children with and without craniosynostosis.

STUDY GROUP

Fifty-seven children with craniosynostosis and their matched controls.

OUTCOME MEASURES

The decayed, missing, and filled teeth and surfaces in both the deciduous (dmfs and dmft) and the permanent dentition (DMFS and DMFT). The plaque and gingivitis scores and developmental enamel defects were also recorded. The caries-related microflora was sampled using an alginate swab and the prevalence of Streptococcus mutans and Lactobacillus and Candida species were recorded.

RESULTS

The dmfs (p <.02) and dmft (p <.01) were significantly greater in the control children. The plaque score for the deciduous dentition only (p <.02) and also the gingivitis score for the permanent teeth only (p <.008) in the craniosynostosis group were significantly greater. The total aerobic bacterial count (p <.004), anaerobic count (p <.002), and Candida count (p <.05) were significantly greater in the control group. The proportion of S. mutans both as a percentage of the total anaerobic count (p <.04) and the total streptococcal count (p <.05) was significantly greater in the control group.

Syndromes involving craniosynostosis and midface hypoplasia

This article reviews a number of well-known syndromes involving craniofacial synostosis and associated midface deficiencies. Syndromes discussed include Apert's, Crouzon's, Saethre-Chotzen, and Carpenter's. Clinical characteristics and genetic defects are discussed. A general approach to surgical management is outlined.

Is craniofacial morphology in Apert and Crouzon syndromes the same?

This article reviews previous research on the craniofacial development in Apert and Crouzon syndromes and adds new roentgencephalometric information. It is concluded that craniofacial development in the two syndromes is not the same. Marked differences were found in the calvaria, cranial base, orbit, maxilla, zygoma, incisal occlusion, and soft tissue profile. In general, abnormal craniofacial morphology was more severe in Apert syndrome than in Crouzon syndrome.

Signalling interactions during facial development

The development of the vertebrate face is a dynamic multi-step process which starts with the formation of neural crest cells in the developing brain and their subsequent migration to form, together with mesodermal cells, the facial primordia. Signalling interactions co-ordinate the outgrowth of the facial primordia from buds of undifferentiated mesenchyme into the intricate series of bones and cartilage structures that, together with muscle and other tissues, form the adult face. Some of the molecules that are thought to be involved have been identified through the use of mouse mutants, data from human craniofacial syndromes and by expression studies of signalling molecules during facial development. However, the way that these molecules control the epithelial-mesenchymal interactions which mediate facial outgrowth and morphogenesis is unclear. The role of neural crest cells in these processes has also not yet been well defined. In this review we discuss the complex interaction of all these processes during face development and describe the candidate signalling molecules and their possible target genes.