Atypical presentation of a newborn with Apert syndrome

Genetic Subtypes of Apert Syndrome Are Associated With Differences in Airway Morphology and Early Upper Airway Obstruction

BACKGROUND

Apert syndrome is predominantly caused by 2 paternally inherited gain-of-function mutations in the FGFR2 gene, Pro253Arg, and Ser252Trp. Studies comparing phenotypic features between these 2 mutations have established differences in syndactyly severity and incidence of cleft palate. Obstructive sleep apnea can be debilitating in a subset of patients with Apert syndrome, yet is not well understood. This study aims to determine whether FGFR2 mutations impart differential effects on airway physiology and morphology.

METHODS

Patients with Apert syndrome and confirmatory molecular testing were reviewed for polysomnography, nasal endoscopy, microlaryngoscopy and bronchoscopy, and computed tomography imaging. Obstructive apnea-hypopnea index and oxygen saturation nadir, nasal airway volumes, choanal cross-sectional area, and midfacial cephalometric dimensions were compared across mutation types.

RESULTS

Twenty-four patients (13 Ser252Trp, 11 Pro253Arg) were included. Severe obstructive sleep apnea (obstructive apnea-hypopnea index>10) occurred in 8 (62%) patients with Ser252Trp mutations compared with 1 (9%) patient with Pro253Arg mutations ( P =0.009). Computed tomography imaging at 1 year of age demonstrated that nasopharyngeal airway volumes were 5302±1076 mm 3 in the Ser252Trp group and 6832±1414 mm 3 in the Pro253Arg group ( P =0.041). Maxillary length (anterior nasal spine-posterior nasal spine, P =0.026) and basion-anterior nasal spine ( P =0.007) were shorter in patients with Ser252Trp mutations.

CONCLUSIONS

The findings suggest that the Ser252Trp mutation in Apert syndrome is associated with higher severity obstructive sleep apnea and decreased nasopharyngeal airway volume. Heightened clinical awareness of these associations may inform treatment planning and family counseling.

Does the Mutation Type Affect the Response to Cranial Vault Expansion in Children With Apert Syndrome?

LEVEL OF EVIDENCE

III.

Cleft Palate in Apert Syndrome

Apert syndrome is a rare genetic disorder characterized by craniosynostosis, midface retrusion, and limb anomalies. Cleft palate occurs in a subset of Apert syndrome patients. Although the genetic causes underlying Apert syndrome have been identified, the downstream signaling pathways and cellular mechanisms responsible for cleft palate are still elusive. To find clues for the pathogenic mechanisms of palatal defects in Apert syndrome, we review the clinical characteristics of the palate in cases of Apert syndrome, the palatal phenotypes in mouse models, and the potential signaling mechanisms involved in palatal defects. In Apert syndrome patients, cleft of the soft palate is more frequent than of the hard palate. The length of the hard palate is decreased. Cleft palate is associated most commonly with the S252W variant of FGFR2. In addition to cleft palate, high-arched palate, lateral palatal swelling, or bifid uvula are common in Apert syndrome patients. Mouse models of Apert syndrome display palatal defects, providing valuable tools to understand the underlying mechanisms. The mutations in FGFR2 causing Apert syndrome may change a signaling network in epithelial–mesenchymal interactions during palatogenesis. Understanding the pathogenic mechanisms of palatal defects in Apert syndrome may shed light on potential novel therapeutic solutions.

Wide Fontanels, Delayed Speech Development and Hoarse Voice as Useful Signs in the Diagnosis of KBG Syndrome: A Clinical Description of 23 Cases with Pathogenic Variants Involving the ANKRD11 Gene or Submicroscopic Chromosomal Rearrangements of 16q24.3

KBG syndrome is a neurodevelopmental autosomal dominant disorder characterized by short stature, macrodontia, developmental delay, behavioral problems, speech delay and delayed closing of fontanels. Most patients with KBG syndrome are found to have a mutation in the ANKRD11 gene or a chromosomal rearrangement involving this gene. We hereby present clinical evaluations of 23 patients aged 4 months to 26 years manifesting clinical features of KBG syndrome. Mutation analysis in the patients was performed using panel or exome sequencing and array CGH. Besides possessing dysmorphic features typical of the KBG syndrome, nearly all patients had psychomotor hyperactivity (86%), 81% had delayed speech, 61% had poor weight gain, 56% had delayed closure of fontanel and 56% had a hoarse voice. Macrodontia and a height range of -1 SDs to -2 SDs were noted in about half of the patients; only two patients presented with short stature below -3 SDs. The fact that wide, delayed closing fontanels were observed in more than half of our patients with KBG syndrome confirms the role of the ANKRD11 gene in skull formation and suture fusion. This clinical feature could be key to the diagnosis of KBG syndrome, especially in young children. Hoarse voice is a previously undescribed phenotype of KBG syndrome and could further reinforce clinical diagnosis.

The Postoperative Morphometrics of Orbital and Maxillary Area for Craniosynostosis

One of the most characteristic features in premature craniosynostosis is fronto-orbital retrusion. The standardized surgical technique of fronto-orbital advancement (FOA) can treat this (some) deformity, such as bilateral coronal synostosis. The purpose of the study is to investigate an available method to assess the postoperative outcome of the craniofacial surgery.

Unilateral Coronal Craniosynostosis in an Apert-Like Patient

Background and Significance

Apert syndrome is a congenital disorder of patients who typically present with bilateral coronal craniosynostosis and varying degrees of complex syndactyly of the hands and feet, among other features. We describe a unique presentation of a rare Apert-like patient with unilateral coronal craniosynostosis and complex syndactyly of the hands and feet.

Case Report

A 2-year-old male patient presented to the craniofacial clinic with his mother due to a concerning head shape. The patient also had bilateral syndactyly of the hands and feet and underwent prior surgical release of the third web space. Computerized tomography of the head illustrated a small open anterior fontanelle, a left harlequin orbit, complete left coronal craniosynostosis, and a patent right coronal suture. The patient subsequently underwent fronto-orbital advancement for expansion of the cranial vault and correction of the asymmetric forehead and orbit. The procedure resulted in improvement of his deformity.

Conclusion

This case illustrates a unique presentation of an acrocephalosyndactyly (ACS) syndrome with asymmetric, unilateral coronal craniosynostosis and complete complex syndactyly of the hands and feet that is most consistent with Apert syndrome. Although the majority of patients with ACS can be categorized into known syndromes, other more unusual presentations must still be considered. Such unique cases are exceedingly rare and only through additional reporting and review of unique phenotypes can new subtypes of common ACS syndromes be classified.

Two patients with Apert syndrome with different mutations: the importance of early diagnosis

Apert syndrome is an autosomal dominant craniosynostosis syndrome accompanied by limb anomalies. The fibroblast growth factor receptor 2 (FGFR2) gene is responsible for the disease and two different heterozygous mutations, p.Pro253Arg and p.Ser252Trp, have been defined as responsible in the majority of cases of Apert syndrome. In this case report, two patients with Apert syndrome with two different FGFR2 gene mutations are presented. Case-1, a 4-month-old boy with craniosynostosis and syndactyly was referred to pediatric genetic clinic. The molecular analysis revealed p.Pro253Arg mutation in the FGFR2 gene, which confirmed the diagnosis of Apert syndrome. Case-2, a 16-year-old girl with developmental delay, cleft palate, syndactyly, and craniosynostosis, was also diagnosed as having Apert syndrome. A molecular diagnosis identified a p.Ser252Trp heterozygous mutation in the FGFR2 gene. Case-1 underwent surgery for craniosynostosis at age 10 months and he was developmentally normal during the 2 year follow-up period. As a conclusion, early surgical intervention should be considered in cases of Apert syndrome to prevent intellectual disability.